CA1294699C - Non-destructive evaluation of ropes by using transverse impulse vibrational wave method - Google Patents
Non-destructive evaluation of ropes by using transverse impulse vibrational wave methodInfo
- Publication number
- CA1294699C CA1294699C CA000583653A CA583653A CA1294699C CA 1294699 C CA1294699 C CA 1294699C CA 000583653 A CA000583653 A CA 000583653A CA 583653 A CA583653 A CA 583653A CA 1294699 C CA1294699 C CA 1294699C
- Authority
- CA
- Canada
- Prior art keywords
- rope
- flaw
- reflected waves
- amplitude
- reflected
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
- B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
- B65H63/00—Warning or safety devices, e.g. automatic fault detectors, stop-motions ; Quality control of the package
- B65H63/06—Warning or safety devices, e.g. automatic fault detectors, stop-motions ; Quality control of the package responsive to presence of irregularities in running material, e.g. for severing the material at irregularities ; Control of the correct working of the yarn cleaner
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01H—MEASUREMENT OF MECHANICAL VIBRATIONS OR ULTRASONIC, SONIC OR INFRASONIC WAVES
- G01H1/00—Measuring characteristics of vibrations in solids by using direct conduction to the detector
- G01H1/04—Measuring characteristics of vibrations in solids by using direct conduction to the detector of vibrations which are transverse to direction of propagation
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/04—Analysing solids
- G01N29/045—Analysing solids by imparting shocks to the workpiece and detecting the vibrations or the acoustic waves caused by the shocks
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N29/00—Investigating or analysing materials by the use of ultrasonic, sonic or infrasonic waves; Visualisation of the interior of objects by transmitting ultrasonic or sonic waves through the object
- G01N29/22—Details, e.g. general constructional or apparatus details
- G01N29/227—Details, e.g. general constructional or apparatus details related to high pressure, tension or stress conditions
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2291/00—Indexing codes associated with group G01N29/00
- G01N2291/26—Scanned objects
- G01N2291/262—Linear objects
- G01N2291/2626—Wires, bars, rods
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Biochemistry (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Engineering & Computer Science (AREA)
- General Health & Medical Sciences (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Textile Engineering (AREA)
- Quality & Reliability (AREA)
- Acoustics & Sound (AREA)
- Investigating Or Analyzing Materials By The Use Of Ultrasonic Waves (AREA)
Abstract
ABSTRACT
A non-destructive method for evaluating ropes, cables, and strands or flaws and tension. The method permit detecting flaws by recognizing certain vibrational wave amplitude and distribution patterns resulting from striking a test subject with a transverse force . Tension on a test subject is calculated by measuring propagation velocity of the vibrational waves through the test subject. An apparatus is provided which produces vibrational waves in a test subject, measures the amplitude and time distribution of the waves, and displays the measurements for analysis.
A non-destructive method for evaluating ropes, cables, and strands or flaws and tension. The method permit detecting flaws by recognizing certain vibrational wave amplitude and distribution patterns resulting from striking a test subject with a transverse force . Tension on a test subject is calculated by measuring propagation velocity of the vibrational waves through the test subject. An apparatus is provided which produces vibrational waves in a test subject, measures the amplitude and time distribution of the waves, and displays the measurements for analysis.
Description
~,~d /f~ ~6~9 ¦~NON-DESTR~CTIVE EVAL~ATION OF ROPES BY ~SING
TRANSVERSE IMPULSE VIBRATIONAL WAVE' METHOD
~ ~1~
3 1 l. ~ield o~_the Invention. The pre~ent invention relate~ to 4 ¦ non-~es~ruc~.ive testing ~f ropes, cables, and ~tal strands ~or 6 ! ~l~ws and tcnsion.
~ I
7 1 2. ~es~ription o~ the Prior Art. No~-de~truc~i~e e~luation , (ND~) of r~pes is known in the ar~. sume NDE methods are ln 9 1 prac~ice, whi~e other m~thod~ have heen proposed, but are not ye~ perfected. As will b~ shown hereinafter, no NDE method ¦ co~bine~ the advantageous features o~ the tran~ver~e impulse ¦ vihra~ onal wave me~hod disclosed i~ this application.
¦ In an article ~ James H. Williams, Jr, John Hainswo~h, ¦ and Samson S. Lee en~itled /'Acous~ic-Ultr~fionic ~ondestr~c~ive l 1¦ EYalu~tlon o~ Double Braid~d Nylon Ropes Using ~he Stre~s WaYe F~ctor" which appeared in ~ibre Sciç~çe and ~echnol~y, 21 ), pp l6g-l80, experiment~ion perform~d on synthe~ic ropes with the obj~ct of ~ons~ructi~g an a~alytical model ¦ wherein ul~ra~onic wave conductivity ~stress Wave Factor) of a ¦ r~pe is A fuhction of the condi~ion of th~ rbpe and the ~ension !i on the rope. It i~ proposed that ~uch a model would enable a~urate ~esting of rope~ for flaws by mea~ring S-~ess ~a~e I P~ctors. To date, n~ Stress W~ve Factor model has be~n 2~
p~oposed ha~inq reliable utili~y for ~op~ test~ng. The ~' variation in the relationship b~tween St~e3s Wav~ ~actor, ,I tension, and rope ~ondltio~ among di~erent ~ope compo~itions and structures is no~ yet ~ully unders~ood.
~8 .I Even if an adequate model for int~rpretin~ Str~s~ Wave : ! ~a&tor ~st resuIts ware found, th~ utility of Stress Wave ¦ Fa~to~ testing would ~ot compare favorably with th~ ~ransverse I impulse vibrational mekhod. Whi.le th~ -transverse impulse .
TRANSVERSE IMPULSE VIBRATIONAL WAVE' METHOD
~ ~1~
3 1 l. ~ield o~_the Invention. The pre~ent invention relate~ to 4 ¦ non-~es~ruc~.ive testing ~f ropes, cables, and ~tal strands ~or 6 ! ~l~ws and tcnsion.
~ I
7 1 2. ~es~ription o~ the Prior Art. No~-de~truc~i~e e~luation , (ND~) of r~pes is known in the ar~. sume NDE methods are ln 9 1 prac~ice, whi~e other m~thod~ have heen proposed, but are not ye~ perfected. As will b~ shown hereinafter, no NDE method ¦ co~bine~ the advantageous features o~ the tran~ver~e impulse ¦ vihra~ onal wave me~hod disclosed i~ this application.
¦ In an article ~ James H. Williams, Jr, John Hainswo~h, ¦ and Samson S. Lee en~itled /'Acous~ic-Ultr~fionic ~ondestr~c~ive l 1¦ EYalu~tlon o~ Double Braid~d Nylon Ropes Using ~he Stre~s WaYe F~ctor" which appeared in ~ibre Sciç~çe and ~echnol~y, 21 ), pp l6g-l80, experiment~ion perform~d on synthe~ic ropes with the obj~ct of ~ons~ructi~g an a~alytical model ¦ wherein ul~ra~onic wave conductivity ~stress Wave Factor) of a ¦ r~pe is A fuhction of the condi~ion of th~ rbpe and the ~ension !i on the rope. It i~ proposed that ~uch a model would enable a~urate ~esting of rope~ for flaws by mea~ring S-~ess ~a~e I P~ctors. To date, n~ Stress W~ve Factor model has be~n 2~
p~oposed ha~inq reliable utili~y for ~op~ test~ng. The ~' variation in the relationship b~tween St~e3s Wav~ ~actor, ,I tension, and rope ~ondltio~ among di~erent ~ope compo~itions and structures is no~ yet ~ully unders~ood.
~8 .I Even if an adequate model for int~rpretin~ Str~s~ Wave : ! ~a&tor ~st resuIts ware found, th~ utility of Stress Wave ¦ Fa~to~ testing would ~ot compare favorably with th~ ~ransverse I impulse vibrational mekhod. Whi.le th~ -transverse impulse .
3~ ' 2 .
I ~ 69g l vi~rational wave method permits testing t~e entlrè length of ~.
rop~ from a sinqle test site near one o~ it5 e~d~, stress Wa~e ~actor me~hod tests only ~ short le~gth of a synt~etic rope ~ecause synthetic ropes quiokly disslpate the energy ~ the vih~ations Use~ i~ Stress ~ave Factor te~ting, ~leotromag~etic NDE are presen~ly ~he only type of non-visual method which ls in current, widespread pr~ct1ce.
8 Electromagneti~ NDE ~ethods are discussed in an article by9 ~ Herbert R. Weische~el ehtitled ~The Inspecti~n of Wire Ropes i~
0 1 Service. A Critical Revie~" appearing in ~aterials Evalua~lon, 43, Decem~er 138~, pp 15~Z~1~05.
12 1 ~lectromagnetic N~E methods are used for: 1) locali~ed ¦ ~ault detection (L.~.) and 2) loss of ~etallic ~ross-sectional 14 1 area testing ~L.M.A.) 16 ~lectromaqnetic NDE meth~ds ~re limited to use ~n 1~ ferromagnetic matexials~ ~nlike t~ansve~rse. i~p~lse vibrational 17 ¦ wave method which may be per~ormed on ferromagnetic or non-8 1 ferromagne~ic materials as well as synthe~ic materials.
I L.F. testing is based on the princlpal th~t broken Wires20 , in a wire rope made o~ ferromagnetic steels distort a maqnetic ¦¦ flux passin~ tha point of breakage caUsing ~agnetic flux ¦¦ leaXage whlch is detectable in the area surrounding the rope.
! L.~. testing is conduct~d by posit~oning a s~rong permanent or ¦¦ electromag~et in close proximity to a wi~e rope to be tested.
I! As th~ rope passes the m~net or ~he magnet is movQd along the ~; , 2~ length of the rope, a magnetic flux is initi~ted in the length a7:: of rope ad~acent to the pole inte~spaGe ~f the maqnet.
2~ Differential sensing eoil~ are positioned around the rope to 2~ ¦ detect magnetic flux leaka~e.
only maior ~laws, such ~s broken wires a~d severe so l Sl ', corrosion pittlhg, are detec~ed b~ L.F~ ~estin~, because only li 3~ ~ 3 1 substantial ch~nges in the m~gnetic flux l.eakage are det~cted 2 by the differ~ntial sensors. Small flaws, or widely dispersed 3 flaws, do not produce substan-tial and r~pid magneti~ rlur 4 l~akage ¢han~es and ~re ofte~ missed using L.F~ testing.
L.M.A. t~s~ involves direct measurement of ~gnetic ~ ¦ fluX through a length of ~ wire rope. Variation in the : ~ m~gne~ic flUX through dif~'erent p~rtions of a singl~ rope i~dicate a change in the ~r~ss-sectional area of the rDpe, whi~h, in turn, indicates possible deterioration of the rope at 'I areas of decre~sed oross-sectional area.
lQ I
11 1 The ele~tromagnetic ~ne~hods require passin~ the entire 12 leng~h of a metallic rope to be tested through the testing 13 1 appara~us or the testing apparatus be moved ~long th~ entire 14 1 len~th of the rope. As wi~h Stress Wave Facto~ testing, the 15 1 necessity ~or access to the entire length o~ a rope reduces tha ¦¦ utility of electromagne~i~ NDE ~ethods.
: 17 ~ Methods base~ on measuring vibra~onal frequencies o~
rn~ n~ c~b~ es far determinin~ te~sion are a].s~ knQwt- ~n the ar~. U.S. Patent No. 45~,099 issuad to Ar~old, U.S. Patent No.
i! ~,376,3~3 issued to Wils~n, and U.S. Patent No. 4,15~,~62 ; !1 issued ~o Conoval each rel~ed ~o ~alculating the tension sn a rope or cable as a ~unction of i~s f~ndam~n~al fxe~uency of Z :
vibration. The squipment and methods shown in these p~ten~s ¦ and otherwise known in the art ar~ no~, howevet, sul~able ~r ¦ practicing t~ non-tension relate~ aspect~ o~ the transverse l¦ impulse vib~ational wave me~ho~ a~ de~cribed ~erein.
27 1 I~ would, therefore, be advanta~eous to develop an ~DE
28 1 ~ethod havin~ utility for testing ferro~agnetic and non-29 ' ferroma~ne~ic ropes alike, which would require ac~ss to only a llmit~d portion of the rope to be teSted, which would dotect ~1 1 3~ :j 4 .i :~Z~4~
1 minor as well as major rope flaws, and ~Ath~ch would permit calculating tensi.on on ropes ~ithout additional equipment.
4 ~M~Y OF THE INV~NTI~N
I ~ 69g l vi~rational wave method permits testing t~e entlrè length of ~.
rop~ from a sinqle test site near one o~ it5 e~d~, stress Wa~e ~actor me~hod tests only ~ short le~gth of a synt~etic rope ~ecause synthetic ropes quiokly disslpate the energy ~ the vih~ations Use~ i~ Stress ~ave Factor te~ting, ~leotromag~etic NDE are presen~ly ~he only type of non-visual method which ls in current, widespread pr~ct1ce.
8 Electromagneti~ NDE ~ethods are discussed in an article by9 ~ Herbert R. Weische~el ehtitled ~The Inspecti~n of Wire Ropes i~
0 1 Service. A Critical Revie~" appearing in ~aterials Evalua~lon, 43, Decem~er 138~, pp 15~Z~1~05.
12 1 ~lectromagnetic N~E methods are used for: 1) locali~ed ¦ ~ault detection (L.~.) and 2) loss of ~etallic ~ross-sectional 14 1 area testing ~L.M.A.) 16 ~lectromaqnetic NDE meth~ds ~re limited to use ~n 1~ ferromagnetic matexials~ ~nlike t~ansve~rse. i~p~lse vibrational 17 ¦ wave method which may be per~ormed on ferromagnetic or non-8 1 ferromagne~ic materials as well as synthe~ic materials.
I L.F. testing is based on the princlpal th~t broken Wires20 , in a wire rope made o~ ferromagnetic steels distort a maqnetic ¦¦ flux passin~ tha point of breakage caUsing ~agnetic flux ¦¦ leaXage whlch is detectable in the area surrounding the rope.
! L.~. testing is conduct~d by posit~oning a s~rong permanent or ¦¦ electromag~et in close proximity to a wi~e rope to be tested.
I! As th~ rope passes the m~net or ~he magnet is movQd along the ~; , 2~ length of the rope, a magnetic flux is initi~ted in the length a7:: of rope ad~acent to the pole inte~spaGe ~f the maqnet.
2~ Differential sensing eoil~ are positioned around the rope to 2~ ¦ detect magnetic flux leaka~e.
only maior ~laws, such ~s broken wires a~d severe so l Sl ', corrosion pittlhg, are detec~ed b~ L.F~ ~estin~, because only li 3~ ~ 3 1 substantial ch~nges in the m~gnetic flux l.eakage are det~cted 2 by the differ~ntial sensors. Small flaws, or widely dispersed 3 flaws, do not produce substan-tial and r~pid magneti~ rlur 4 l~akage ¢han~es and ~re ofte~ missed using L.F~ testing.
L.M.A. t~s~ involves direct measurement of ~gnetic ~ ¦ fluX through a length of ~ wire rope. Variation in the : ~ m~gne~ic flUX through dif~'erent p~rtions of a singl~ rope i~dicate a change in the ~r~ss-sectional area of the rDpe, whi~h, in turn, indicates possible deterioration of the rope at 'I areas of decre~sed oross-sectional area.
lQ I
11 1 The ele~tromagnetic ~ne~hods require passin~ the entire 12 leng~h of a metallic rope to be tested through the testing 13 1 appara~us or the testing apparatus be moved ~long th~ entire 14 1 len~th of the rope. As wi~h Stress Wave Facto~ testing, the 15 1 necessity ~or access to the entire length o~ a rope reduces tha ¦¦ utility of electromagne~i~ NDE ~ethods.
: 17 ~ Methods base~ on measuring vibra~onal frequencies o~
rn~ n~ c~b~ es far determinin~ te~sion are a].s~ knQwt- ~n the ar~. U.S. Patent No. 45~,099 issuad to Ar~old, U.S. Patent No.
i! ~,376,3~3 issued to Wils~n, and U.S. Patent No. 4,15~,~62 ; !1 issued ~o Conoval each rel~ed ~o ~alculating the tension sn a rope or cable as a ~unction of i~s f~ndam~n~al fxe~uency of Z :
vibration. The squipment and methods shown in these p~ten~s ¦ and otherwise known in the art ar~ no~, howevet, sul~able ~r ¦ practicing t~ non-tension relate~ aspect~ o~ the transverse l¦ impulse vib~ational wave me~ho~ a~ de~cribed ~erein.
27 1 I~ would, therefore, be advanta~eous to develop an ~DE
28 1 ~ethod havin~ utility for testing ferro~agnetic and non-29 ' ferroma~ne~ic ropes alike, which would require ac~ss to only a llmit~d portion of the rope to be teSted, which would dotect ~1 1 3~ :j 4 .i :~Z~4~
1 minor as well as major rope flaws, and ~Ath~ch would permit calculating tensi.on on ropes ~ithout additional equipment.
4 ~M~Y OF THE INV~NTI~N
5 ¦ It is an ohjeot o~ the prese~t lnvention to provlde an 8 app~r~tu~ and non-destrllc1:~ve ~v~ ;.~n m~tho~ ~h~c~h apprises 7 a user ~ flaws in, ~nd tension o~, ~ ¢able, rope, or metal 8 strand.
~ It is ano~her objec~ of the present invention to pro~.ide lO I an apparatus and non-destructive evaluation metho~ which ll ¦ appri~es ~ user of the relative ampli~ude~ and ~rrival ti~e of ~2 1 pulsed, ~ransverse, vibrational waves passin~ through cable, 13 , rope, and metal strand, t is another ob~ect of the present invention to provide 16 ~n apparatus and non-destructive evaluation method hy which the 18 location of a fl~w in ~ cable, rope, or metal s~r~nd is de~ermined .
~7 18 It is ano~her object o~ the present i.nvention to provide l9 an apparatus and non~d~structive evaluatiorl method by which the 20 I overall flaw population of a tes~ed cable, ropa, or me~al 21 1 strand may ~e determined.
2~ ~I It is another oh~ect of t~e present invention to pro~ide I
23 an apparatus and non-destru~tive evalu~tion method b~ which th~
tension on cable, rope, or metal strand may be ~easured.
:8~ Accordin~lyj the present invention provides ~n appara~3s and method u~ilizing pulsed, ~ransverse, vibrational waves ~or ~ non-destructive ~valuation o~ cables, rop~, and metal stran~s 28 for flaws and for tension, The method is re~crred to as ~ransverse i~pul~e vibrational wave me~hod.
. ~ The apparatus ~or transverse impulse vibrational wav~
I¦ me~hod is de~igned for initiating a transverse vi~rational wave Il ~ 3g 1 motion in a xope, and for measuring the amplitude of and time 2 intervals between the resulting waves as they travel though the 3 rope. The apparatus comprises an exciting mechanism which 4 applies a transverse impulsive force to the ~ested rope, a 6 sensor which detects individual waves as they pass a particular ~ point on the rope, a signal amplifier which raises the 7 amplitude of the electrical signals form the sensor, a signal 8 conditioner which filters unwanted signals ~rom the sensor/ and 9 an oscilloscope which displays the measurements of the sensor in time versus amplitude units.
11 The apparatus optionally includes a computer and recorder 12 or graphics printer. The computer is for automating the 13 measurements and calculations involved in detecting and 14 locating flaws in a tested rope, as well as in determining the 16 tension on a tested rope. The recorder and graphics printer 1~ are for recording and producing a permanent record of the 17 time/amplitude relationships of the vibrational waves as 18 detected by the sensor.
}9 The transverse impulse vibrational method for NDE of ropes is based on the fact that flaws in a rope partially reflect ~0 21 vibrational wave energy because of the acoustic impedance mismatches at the flaw locations. The wave is also reflected as at the ends (or terminations) of the rope. The sensor of the 24 above-described testing apparatus producas corresponding electrical signals.
Calculations based on measurements of the time betwaen the 2~
27 flaw signals and the end-reflected signals and on measurements 28 o~ the relative amplitudes of the signals detected by the testing apparatus allow the user to locate rope flaws, to determine tension on the tested rope, and to measure the i :L294699 1 1 relative population of flaws in the ~ested rope as compare~ to a ~on~rol ~ope sample.
4 BRIE~_DESRIPTIO~ ~F_THE DRAWINGS
5 1 ~ig. 1 is a sche~atic depiction o~ the tes~in~ apparatus l for transverse ~mpulse vlbr~tlon~ ave method along with a r 1I roPe ~r te~ting, 'i Fig. 2 shows ~ magnet/coil combination sensor.
g !¦ Fig. 3 shows the transverse impul~e vibrational wave 'I ~e~hod testing ~pparatus set ~p for field testing a large guy I wire.
11 '~
12 Flg. ~ shows an exa~ple of an oscilloscope display ¦ obtained by using th~ tran~v~r6s impul~e vibrat~onal m~od, appearing with Fig. 1.
14 ,I DE~AILED DE5CRIPTION O~ ~HE_PR~F~RRED EMBODIMENT
16 The present invention comprises a method and apparatus fo~
non-destructive evaluation (ND~) of cables, synthetic rope~, ,¦ and wire ropes ~or tension and flaws. ThP method will be : ¦¦ referred ~o as ~transverse impulse vibrational wave metho~
¦ herein. Por the purpos~s of this discussion, cable, syn~h~tic rope, or wixe rope w~ll be ~eerred to ~ollectively a~ r'rope"
~0 ', in m~st instances.
. 21 '!
Referrin~ to Fiqure 1, the testlny appara~us i~ d~picted ~2 schematically, and is ref~red to ~enerally by the reference '! numeral 10. ~or reasons to be discussed hereinafter, the ~4 test1~g apparatus 10 is for detecting individual vibrational wava~ in ~ rop~ 12 ~nd apprigin~ a u~er of th~ pre~ence, ~he ¦I relntive amplitudes, and the sequential arrangement o~ the ves.
2~ 1 ~ A ~ope 12 i~ shown in Figures 1, 2 and 3 to show the I relati~nsh~p of the testing apparatus' 10 co~ponents to a rop~
I lZ which is to be tested.
31 ~
~2 ~, 7 ~I
;' l ~2~ 9 l Transverse Impulse Vibra~ional (TIV) wave method invol~es 2 ¦ strlking a rope 12 to propa~ate vibra~ional wa~es through the 3 ¦ rope 12~ Consi~tency in the force us~d to strike the rope 12 ~ ¦ i6 d~irablç ~rom ono te6~ t~ a~o~h~r. Con~ en~y o~ ~t~king 5 1 ~o~ce permits dir~ct analytical comparisons to ~e made betw~en ~ data derived ~rom tests of the same rope at ~fferent poi~s in 7 the rope'~ 12 servic~ lif~, or from tests of dif~erent rope~.
8 Therefore, the te~ting apparatus 10 includes a striking ~ mechanism 14 whi~h consis~ently strikes the rope 12 with a predetermined force. ~he s~iXing mechanism 14 of the ~1 i pre~erre~ embo~iment is a solenoid 16 with its plunger 1~ in a 12 1 position for striking the rope 12 when the solenoid 16 ~s 13 1 ac~v~ed (se~ Figure 3). Other desiyns for st~iking ¦¦ mechanisms 14 such ~s pneumatic devices o~ spring biased 16 ¦ devices (not hown) would be e~ually acceptable.
I lB ! It is noted that although any manner of s~riking the rope : ¦ 12 is acceptabl~ fo~ any given ~e~t; a device provid~ng l~ ¦ consis~ent stri~lng force is merety de ir~ble for ~e above-¦ stated reasons On~ could, for instançe~ su~çes~fully conduct a ~IV wave method test by st~iking ~he rope 12 with a ha~er not Yhow~.
I Refer~ing a~ain to Figure 1, a s~nsor ~O is in~luded in the testing appara~us 10 for ~ete~tin~ indi~idual vi~ratlon~l : ,' waves in the rope 12 resulting ~rom the impact ~rom the striking mechanism ~4. To permit testing of a wide range of l! sizes and compositions o~ ~opes, cables, and strands, the : 2~ 1 ensor 20 ~h~u1d b~ ~p~ble of di~ernillg in~ivi~ual vibrational ~ves ranging in ~reqUenCy up to approximatQly l lK~z : 29 I Th~ pa~cular m~thod o~ de~ec~i~n for the sensor 20 ~s SO l l not important ~o long as th~ rela~iv~ amplitudes and sequential 51 , 32 ~ 8 1~
I
' ~LZg~99 1 arrangement of vibr~tional wav~s in the rope 12 may be derlve~
2 from the ~ensor's 20 ou~put. The ~ensor 20 ~ay measure the ~pe's 12 actual ~isplacement, ve~ocity of displa~ement, or 4 acceleration of displacement.
Re~erring to Figure 2, one type of sensor 20 which has ~ ~en used for TI~ wave method comprises a co~l 22 and permanent 7 magnet ~4 com~ina~ion. Coil 22 is a~ache~ ~O the rope lZ, an~
~ I i~ placed between the positi~e pole 26 and the ~cgativ~ pola 2~
3 of the ma~net 24. The leads 30 of the coil 22 are att~ched to the componen~s of the testing ~pp~r~tus 10 which proce~s the ¦ se~sor's 20 output. As the rope 12 vibrate~, it cause~ the 1~ 1 attached coil 22 to move rela~i~e to the ~ield o~ the ma~ne~
13 1 24. A voltage po~ential ~or each such movement is created, and 14 1 ~he resul~in~ electrical signals are detected and p~oce~eed ~y 1! 24. The relative motion of the coil 22 within the magnetic ¦¦ field created by magnet 24, induces a current to flow within the ¦ coil 22. This curren-t flow is in direct proportion to the ~7 magnitude of the relative motion of coil 22 within the magnetic ~3 1 ,¦ field which is in turn directly related to the magnitude of the ¦¦ vi~rational wave within the rope 12. The induced current flow 21 ¦ within coil 22 thereby provides the necessary electrical signal ll to be processed and analy~ed by the remaining components of the a~ ~ testlng apparatus 10. Any other available electromagnetic 24 11 displacement sensor such as the Electro-Mike Displacement 25 1' ~ransducer manufactured by the Electro Corp. of Sarasota, 2~ I Florida, would likewise be appropriate.
27 ' Other designs for the sensor 20 are equally acceptable.
28 1 Devices which physically contact the rope 12 or which detect a~ ~I vibrations by optical methods are examples. An optical sensor ~0 ¦¦ 20 such a~ a las~r vibration sensor is shown in Figure 3. An 31 ll optical sensor 20 has the advantage of not requiring any direct 32 li attachment to rope 12. Light may be directed at the vibrating Il rope 12 from a dis-tance and may likewise be detected at a 1 ¦ distance as shown in Figure 3. Any available op-tical device 2 j capable of quantitatively detecting the vibrations of the rope 3 ll 12, such as the Laser Through Beam Photoelectric Sensor, LX
~ Series, manufactured by the Keyence Company, Ltd. of North America, would likewise be appropriate.
~ ! Referrlng to Figure 1, the testing appara~us 10 ~nclu~es ~
7 !I signal amplifier 3~ whic~ is c~nnected to the ~ensor ~0. The 8 ~! 3ig~ mpli~icr 32 ~i~e~ the ~lectrio~l s~gn~l~ from the sensor 20 and amplifies the signals to a level capable of beiny detected and processed by ~he other components of the testing apparatus 10. The amplitudes o~ the signals produced by the .¦ signal ampllfier 32 are higher, but directly proportional to I¦ the amplitudes of the electrical signals from the sensor 20.
¦¦ The signal amplifier'~ 32 output~ ~re, there~ore, propor~ional ¦ to the amplitude~ of the actu~l vibrational waves in the rope i 12. ~he relAtive ~plitud~s o~ thc vi~rat~o~al wav~ ~n tn~
,I rope 12 are i~portan~ ~o ~IV wave me~hod analy~i~. The 7 !i frequency response of ~he signal amplifier 3~ should be at I8 l le~st coex~ensive with the sensor 20.
9 i The testing apparatu~ 10 furthe~ in~ludes a signal ~ ~i condition~r 34 which is connected to the signal amplifier 32 2~ ~ for receivin~ the amplified signals. The signal conditioner 34 a2 j is ~ variable filter which filters signal ~requancies ~ro~ ~he 23 signal amplifier 32 falling within a user-defined range. This 24 ~ allows a user to filt~r sign~ls which are not useful ~or ~he ~ !! te~t ~eing condu~ted.
2B il Referring in combination to Figures 1 and ~, ~ digi~iæing 27 ¦ oscillos~ope 36 is believed to be the pre~erre~
2~ I reco~din~display ~evice for the testing apparatus 10. The 29 , oscilloscope 3 6 is connected to ~he signal conditioner 34 for 50 ¦ receiv~ng the signals ~rom the signal aondition~r 34. ~e 31 .
i.
~ ~2~ g 1 oscilloscope~s 36 ~isplay ~8 ~as a y-axis scale 40 measured in 2 amplitu~e units, and an x axis ~cale 42 measured in time units.
3 ~he oscilloscope 36 has calibration controls 43 ~or ad~usting th~ display 38 to units appropriate to the particular rope 12 being te~ed.
~ he diglti~ing os~illo~cope 3~ not ~nl~ gi~eS a graph~c~l r~p~esentatlon of the relatiYe ampli~udes and sequen~ial ar~a~gemen~ o~ ~he signals rom the signal conditioner 34, and S l consequently those o~ ~he actual vibrational waves in the rope 10 ¦ 12, but also records the signa~s for later re-display or 11 ¦ c~mputex analy~is.
~ It is ano~her objec~ of the present invention to pro~.ide lO I an apparatus and non-destructive evaluation metho~ which ll ¦ appri~es ~ user of the relative ampli~ude~ and ~rrival ti~e of ~2 1 pulsed, ~ransverse, vibrational waves passin~ through cable, 13 , rope, and metal strand, t is another ob~ect of the present invention to provide 16 ~n apparatus and non-destructive evaluation method hy which the 18 location of a fl~w in ~ cable, rope, or metal s~r~nd is de~ermined .
~7 18 It is ano~her object o~ the present i.nvention to provide l9 an apparatus and non~d~structive evaluatiorl method by which the 20 I overall flaw population of a tes~ed cable, ropa, or me~al 21 1 strand may ~e determined.
2~ ~I It is another oh~ect of t~e present invention to pro~ide I
23 an apparatus and non-destru~tive evalu~tion method b~ which th~
tension on cable, rope, or metal strand may be ~easured.
:8~ Accordin~lyj the present invention provides ~n appara~3s and method u~ilizing pulsed, ~ransverse, vibrational waves ~or ~ non-destructive ~valuation o~ cables, rop~, and metal stran~s 28 for flaws and for tension, The method is re~crred to as ~ransverse i~pul~e vibrational wave me~hod.
. ~ The apparatus ~or transverse impulse vibrational wav~
I¦ me~hod is de~igned for initiating a transverse vi~rational wave Il ~ 3g 1 motion in a xope, and for measuring the amplitude of and time 2 intervals between the resulting waves as they travel though the 3 rope. The apparatus comprises an exciting mechanism which 4 applies a transverse impulsive force to the ~ested rope, a 6 sensor which detects individual waves as they pass a particular ~ point on the rope, a signal amplifier which raises the 7 amplitude of the electrical signals form the sensor, a signal 8 conditioner which filters unwanted signals ~rom the sensor/ and 9 an oscilloscope which displays the measurements of the sensor in time versus amplitude units.
11 The apparatus optionally includes a computer and recorder 12 or graphics printer. The computer is for automating the 13 measurements and calculations involved in detecting and 14 locating flaws in a tested rope, as well as in determining the 16 tension on a tested rope. The recorder and graphics printer 1~ are for recording and producing a permanent record of the 17 time/amplitude relationships of the vibrational waves as 18 detected by the sensor.
}9 The transverse impulse vibrational method for NDE of ropes is based on the fact that flaws in a rope partially reflect ~0 21 vibrational wave energy because of the acoustic impedance mismatches at the flaw locations. The wave is also reflected as at the ends (or terminations) of the rope. The sensor of the 24 above-described testing apparatus producas corresponding electrical signals.
Calculations based on measurements of the time betwaen the 2~
27 flaw signals and the end-reflected signals and on measurements 28 o~ the relative amplitudes of the signals detected by the testing apparatus allow the user to locate rope flaws, to determine tension on the tested rope, and to measure the i :L294699 1 1 relative population of flaws in the ~ested rope as compare~ to a ~on~rol ~ope sample.
4 BRIE~_DESRIPTIO~ ~F_THE DRAWINGS
5 1 ~ig. 1 is a sche~atic depiction o~ the tes~in~ apparatus l for transverse ~mpulse vlbr~tlon~ ave method along with a r 1I roPe ~r te~ting, 'i Fig. 2 shows ~ magnet/coil combination sensor.
g !¦ Fig. 3 shows the transverse impul~e vibrational wave 'I ~e~hod testing ~pparatus set ~p for field testing a large guy I wire.
11 '~
12 Flg. ~ shows an exa~ple of an oscilloscope display ¦ obtained by using th~ tran~v~r6s impul~e vibrat~onal m~od, appearing with Fig. 1.
14 ,I DE~AILED DE5CRIPTION O~ ~HE_PR~F~RRED EMBODIMENT
16 The present invention comprises a method and apparatus fo~
non-destructive evaluation (ND~) of cables, synthetic rope~, ,¦ and wire ropes ~or tension and flaws. ThP method will be : ¦¦ referred ~o as ~transverse impulse vibrational wave metho~
¦ herein. Por the purpos~s of this discussion, cable, syn~h~tic rope, or wixe rope w~ll be ~eerred to ~ollectively a~ r'rope"
~0 ', in m~st instances.
. 21 '!
Referrin~ to Fiqure 1, the testlny appara~us i~ d~picted ~2 schematically, and is ref~red to ~enerally by the reference '! numeral 10. ~or reasons to be discussed hereinafter, the ~4 test1~g apparatus 10 is for detecting individual vibrational wava~ in ~ rop~ 12 ~nd apprigin~ a u~er of th~ pre~ence, ~he ¦I relntive amplitudes, and the sequential arrangement o~ the ves.
2~ 1 ~ A ~ope 12 i~ shown in Figures 1, 2 and 3 to show the I relati~nsh~p of the testing apparatus' 10 co~ponents to a rop~
I lZ which is to be tested.
31 ~
~2 ~, 7 ~I
;' l ~2~ 9 l Transverse Impulse Vibra~ional (TIV) wave method invol~es 2 ¦ strlking a rope 12 to propa~ate vibra~ional wa~es through the 3 ¦ rope 12~ Consi~tency in the force us~d to strike the rope 12 ~ ¦ i6 d~irablç ~rom ono te6~ t~ a~o~h~r. Con~ en~y o~ ~t~king 5 1 ~o~ce permits dir~ct analytical comparisons to ~e made betw~en ~ data derived ~rom tests of the same rope at ~fferent poi~s in 7 the rope'~ 12 servic~ lif~, or from tests of dif~erent rope~.
8 Therefore, the te~ting apparatus 10 includes a striking ~ mechanism 14 whi~h consis~ently strikes the rope 12 with a predetermined force. ~he s~iXing mechanism 14 of the ~1 i pre~erre~ embo~iment is a solenoid 16 with its plunger 1~ in a 12 1 position for striking the rope 12 when the solenoid 16 ~s 13 1 ac~v~ed (se~ Figure 3). Other desiyns for st~iking ¦¦ mechanisms 14 such ~s pneumatic devices o~ spring biased 16 ¦ devices (not hown) would be e~ually acceptable.
I lB ! It is noted that although any manner of s~riking the rope : ¦ 12 is acceptabl~ fo~ any given ~e~t; a device provid~ng l~ ¦ consis~ent stri~lng force is merety de ir~ble for ~e above-¦ stated reasons On~ could, for instançe~ su~çes~fully conduct a ~IV wave method test by st~iking ~he rope 12 with a ha~er not Yhow~.
I Refer~ing a~ain to Figure 1, a s~nsor ~O is in~luded in the testing appara~us 10 for ~ete~tin~ indi~idual vi~ratlon~l : ,' waves in the rope 12 resulting ~rom the impact ~rom the striking mechanism ~4. To permit testing of a wide range of l! sizes and compositions o~ ~opes, cables, and strands, the : 2~ 1 ensor 20 ~h~u1d b~ ~p~ble of di~ernillg in~ivi~ual vibrational ~ves ranging in ~reqUenCy up to approximatQly l lK~z : 29 I Th~ pa~cular m~thod o~ de~ec~i~n for the sensor 20 ~s SO l l not important ~o long as th~ rela~iv~ amplitudes and sequential 51 , 32 ~ 8 1~
I
' ~LZg~99 1 arrangement of vibr~tional wav~s in the rope 12 may be derlve~
2 from the ~ensor's 20 ou~put. The ~ensor 20 ~ay measure the ~pe's 12 actual ~isplacement, ve~ocity of displa~ement, or 4 acceleration of displacement.
Re~erring to Figure 2, one type of sensor 20 which has ~ ~en used for TI~ wave method comprises a co~l 22 and permanent 7 magnet ~4 com~ina~ion. Coil 22 is a~ache~ ~O the rope lZ, an~
~ I i~ placed between the positi~e pole 26 and the ~cgativ~ pola 2~
3 of the ma~net 24. The leads 30 of the coil 22 are att~ched to the componen~s of the testing ~pp~r~tus 10 which proce~s the ¦ se~sor's 20 output. As the rope 12 vibrate~, it cause~ the 1~ 1 attached coil 22 to move rela~i~e to the ~ield o~ the ma~ne~
13 1 24. A voltage po~ential ~or each such movement is created, and 14 1 ~he resul~in~ electrical signals are detected and p~oce~eed ~y 1! 24. The relative motion of the coil 22 within the magnetic ¦¦ field created by magnet 24, induces a current to flow within the ¦ coil 22. This curren-t flow is in direct proportion to the ~7 magnitude of the relative motion of coil 22 within the magnetic ~3 1 ,¦ field which is in turn directly related to the magnitude of the ¦¦ vi~rational wave within the rope 12. The induced current flow 21 ¦ within coil 22 thereby provides the necessary electrical signal ll to be processed and analy~ed by the remaining components of the a~ ~ testlng apparatus 10. Any other available electromagnetic 24 11 displacement sensor such as the Electro-Mike Displacement 25 1' ~ransducer manufactured by the Electro Corp. of Sarasota, 2~ I Florida, would likewise be appropriate.
27 ' Other designs for the sensor 20 are equally acceptable.
28 1 Devices which physically contact the rope 12 or which detect a~ ~I vibrations by optical methods are examples. An optical sensor ~0 ¦¦ 20 such a~ a las~r vibration sensor is shown in Figure 3. An 31 ll optical sensor 20 has the advantage of not requiring any direct 32 li attachment to rope 12. Light may be directed at the vibrating Il rope 12 from a dis-tance and may likewise be detected at a 1 ¦ distance as shown in Figure 3. Any available op-tical device 2 j capable of quantitatively detecting the vibrations of the rope 3 ll 12, such as the Laser Through Beam Photoelectric Sensor, LX
~ Series, manufactured by the Keyence Company, Ltd. of North America, would likewise be appropriate.
~ ! Referrlng to Figure 1, the testing appara~us 10 ~nclu~es ~
7 !I signal amplifier 3~ whic~ is c~nnected to the ~ensor ~0. The 8 ~! 3ig~ mpli~icr 32 ~i~e~ the ~lectrio~l s~gn~l~ from the sensor 20 and amplifies the signals to a level capable of beiny detected and processed by ~he other components of the testing apparatus 10. The amplitudes o~ the signals produced by the .¦ signal ampllfier 32 are higher, but directly proportional to I¦ the amplitudes of the electrical signals from the sensor 20.
¦¦ The signal amplifier'~ 32 output~ ~re, there~ore, propor~ional ¦ to the amplitude~ of the actu~l vibrational waves in the rope i 12. ~he relAtive ~plitud~s o~ thc vi~rat~o~al wav~ ~n tn~
,I rope 12 are i~portan~ ~o ~IV wave me~hod analy~i~. The 7 !i frequency response of ~he signal amplifier 3~ should be at I8 l le~st coex~ensive with the sensor 20.
9 i The testing apparatu~ 10 furthe~ in~ludes a signal ~ ~i condition~r 34 which is connected to the signal amplifier 32 2~ ~ for receivin~ the amplified signals. The signal conditioner 34 a2 j is ~ variable filter which filters signal ~requancies ~ro~ ~he 23 signal amplifier 32 falling within a user-defined range. This 24 ~ allows a user to filt~r sign~ls which are not useful ~or ~he ~ !! te~t ~eing condu~ted.
2B il Referring in combination to Figures 1 and ~, ~ digi~iæing 27 ¦ oscillos~ope 36 is believed to be the pre~erre~
2~ I reco~din~display ~evice for the testing apparatus 10. The 29 , oscilloscope 3 6 is connected to ~he signal conditioner 34 for 50 ¦ receiv~ng the signals ~rom the signal aondition~r 34. ~e 31 .
i.
~ ~2~ g 1 oscilloscope~s 36 ~isplay ~8 ~as a y-axis scale 40 measured in 2 amplitu~e units, and an x axis ~cale 42 measured in time units.
3 ~he oscilloscope 36 has calibration controls 43 ~or ad~usting th~ display 38 to units appropriate to the particular rope 12 being te~ed.
~ he diglti~ing os~illo~cope 3~ not ~nl~ gi~eS a graph~c~l r~p~esentatlon of the relatiYe ampli~udes and sequen~ial ar~a~gemen~ o~ ~he signals rom the signal conditioner 34, and S l consequently those o~ ~he actual vibrational waves in the rope 10 ¦ 12, but also records the signa~s for later re-display or 11 ¦ c~mputex analy~is.
12 Refexring agai~ to Figur~ 1, a trigger swit~h 44 activates 13 the striking mechanism 14 and provides a synchronization ~ignal 14 to start the digitizing oscilloscope ~6. Therefore, a user may 1~ 1 simply throw the switch 44, and the striking mechanism 14 will 13 !¦ strike the rope ~nd the electronic components of the tes~in~
17 l; apparatus lo will then p~OC2SS and record the resulting ~ vibrational waves. If a co~puter 58 is used (to be disc~s~ed 19 1l hereina~ter) t~e computer 58 may be interfaced with the swi~ch 20 1 44 and it may activate the co~ponent~ of the testing apparatus ~1 ! lo 2 3 1 Transverse impulse vibrational wave me~hod may be 2 ' conducted through anal~sig ~f data ~hich may be derived by the ~4 tes~ing apparatus 10 as just ~escribed. Transverse impulse 2B ~! vibrational wave m~a~hod is made po~sibl~ }:)ecause of the i! measur~ble e~ect tha~ flaws and cension have on the 27 ¦ vibrational wave propaga~ion properties of oa~les, rop~s, and 2~ ¦ ~trands.
29 1 It is impo~ant ~o note tha~ TIV wave method may be 50, pe~ormed on fe~romagne~i~ and non-ferromagnetic metallic 31, materials as well as non-metallic materials aliXe. This ~iva~
32, !~ 11 ~.2~
1 TlV wave me~hod a considera~le utill~arian advantage over pre~ently used NDE methods. It is o~ furt~er impor~ance that ~ TIV wave method alone pe~n~ts testing an entire length of a 4 ~able, rope, or stran~ ~rom a single ~cess p~i~t at one end.
As previously men~loned t o~her ~D~ method~ ~e~uire passing ~he ~ tes~ing apparatus ove~ the enti~e length o~ a test sub~ect.
7 Re~erring to Figure 3, TIV wave method will normally be 8 per~ormed on ~bl~, rop~s, or metal strands which are in ~ ¦ service as ele~ator cables, ~uy wires, or in si~ilar hlgh-10 ' stres~ and/or safety intensive applications. To perform a T~Vwave method tes~, the ~triking mechanism 14 is placed withi~ a specified distan~e o~ the rope 12 whiCh ls to be tested.
13 ¦ Because a~alysis of the test results are simplified by having ~ the sensor 2a in close proxi~ity to the striking mechanism 14, 16 ¦¦ the s~xiking mechanism 14 and the ~ensor 20 are mounted on a ! slngle support stand ~6. The remaining compon~nt~ of the ~7 ¦ testing app~ratus 10 are connected as discus~ed abo~e. A
por~able power upply 40 is shown in ~i~ure 3 for Use in ar~a~
where electricity for the tes~ing apparatus 10 is not readily ¦ available.
~0 Ij 2L !I The ~triking mechanis~ 14 and the sensor 20 should be ¦ pl~ced near one end 50 o~ the ~ope 12. This simplifies ! analysis oY tests results because ~ wa~e approaGhes and then is reflected by the end 50 of the rop~ 12 closest ~o t~e sensor 2~ i Z0. These waves will p~ss the sensor 20 a very shor~ tim~
2~ 1 apart. ~hereore, the two passages appear, and can be treated 27 as a single wave for p~rposes of TIV wave n~ethod.
28 ¦ For simplici~y~s sake, the vibrational ~aves ~reated by 29 ~ the impact of the ~trikin~ mecha~ism 14 will be ~eferred ~o as 30 1 a sLngle wave in the following dis~ussion.
51 1 Referring in ~ombination to Fi~re~ 1, 3, and 4, when 32 ~, 12 5.~,`` 1 I
1 ! test is conduc~ed ~ith the ~esting apparatus 10, -~he rope 12 is a ¦, struck by the striking mechanism 14, and a vibra~ional wave is 3 ll propagated fro~ the point of i~pact. ~s the incideh~ wave ~ reaches an end 50 of the ~ope 12, it is reflected and travels S towards the ~pposite end 50 where it is again r~lected, ~his ~ cycle continues until th~ energy in the rope 12 is completely 7 ~ dissipat~d, A flaw 52 in ~he rope 12 also re~lects vibrati~nal waves, but to a lesser ex~ent t~lan ~he rope's 12 ends ~0.
9 ¦ TherP~ore, wave~ reflected by the flaw 5~ will have a lesser amplitude than waves re~lecte~ by th~ rope's ends 50. Flaw-eflected waves appear, in ~ime, between en~-re~lected waves b~cause f~aw-re~lected waves travel a shor~er distance than 13 ~I end-reflected waves.
I
14 1 As disau~sed abo~e, the sensor 20 will produce an 16 electrical signal in response to each vibrational wave of de~ectable amplitude which passes it. Each ele¢trical signal ¦ will have an amplitude proportional to the ~pli~ud~ o~ its respec~ive vibrational wave. S~gnals from an ~nd-re~lec~d ¦ wave ~11, like the wave itself, ha~e a larger amplitude than .¦ signals reflectin~ ~la~-~eflected wa~es. Flaws which are large ~i enough ~o pro~ide re~lected w~ves of measu~able amplitude are il re~erred to as "discrete flaws."
! Flaws which are too small to reflect such Waves are .! referred to as nnon-disc~e~e flaws" (not shown), ~hîle not ind1vidually detectable, the presence o~ non-discrete flaw~ may !! be recognized by me~hods which will be cliscussed hereina~ter.
xr l Referxing ~o Figure 4, a discrete flaw is indicate~ in the 1~ oscilloscope display ~a a~ a low amplitude ~law signal 54 intervenlng higher amplitude end signals 56. When a ~law . signal 54 does appear, calculations Inay be conducted to locate ~ ' the discrete flaw 52 ~shown in Figure 3) which it represen~.
3~ 13 !
i. I
ll 1 i I ~eferring ag~in to Figure 4, the pulse signal 55 i~ ~e ~ wav~ directly resul~ing from the imp~c~ ~rom the striking 4 ' ~.echanism 14, and may be t~ea~ed as ~n end signal 56.
6 The position of ea~h discrete ~law 52, the tension on ~he 6 rope, and the presence of non~di~cre~e ~law~ (hO~ shown) are 7 determined by formulae, one or more of whioh ~eguire the 8 ~ollowing var~ables whiGh may he derived rom the os~illosoope ! display 38-~ r ~ the time lnterval between ad~acent end signals 12 ' 56.
17 l; apparatus lo will then p~OC2SS and record the resulting ~ vibrational waves. If a co~puter 58 is used (to be disc~s~ed 19 1l hereina~ter) t~e computer 58 may be interfaced with the swi~ch 20 1 44 and it may activate the co~ponent~ of the testing apparatus ~1 ! lo 2 3 1 Transverse impulse vibrational wave me~hod may be 2 ' conducted through anal~sig ~f data ~hich may be derived by the ~4 tes~ing apparatus 10 as just ~escribed. Transverse impulse 2B ~! vibrational wave m~a~hod is made po~sibl~ }:)ecause of the i! measur~ble e~ect tha~ flaws and cension have on the 27 ¦ vibrational wave propaga~ion properties of oa~les, rop~s, and 2~ ¦ ~trands.
29 1 It is impo~ant ~o note tha~ TIV wave method may be 50, pe~ormed on fe~romagne~i~ and non-ferromagnetic metallic 31, materials as well as non-metallic materials aliXe. This ~iva~
32, !~ 11 ~.2~
1 TlV wave me~hod a considera~le utill~arian advantage over pre~ently used NDE methods. It is o~ furt~er impor~ance that ~ TIV wave method alone pe~n~ts testing an entire length of a 4 ~able, rope, or stran~ ~rom a single ~cess p~i~t at one end.
As previously men~loned t o~her ~D~ method~ ~e~uire passing ~he ~ tes~ing apparatus ove~ the enti~e length o~ a test sub~ect.
7 Re~erring to Figure 3, TIV wave method will normally be 8 per~ormed on ~bl~, rop~s, or metal strands which are in ~ ¦ service as ele~ator cables, ~uy wires, or in si~ilar hlgh-10 ' stres~ and/or safety intensive applications. To perform a T~Vwave method tes~, the ~triking mechanism 14 is placed withi~ a specified distan~e o~ the rope 12 whiCh ls to be tested.
13 ¦ Because a~alysis of the test results are simplified by having ~ the sensor 2a in close proxi~ity to the striking mechanism 14, 16 ¦¦ the s~xiking mechanism 14 and the ~ensor 20 are mounted on a ! slngle support stand ~6. The remaining compon~nt~ of the ~7 ¦ testing app~ratus 10 are connected as discus~ed abo~e. A
por~able power upply 40 is shown in ~i~ure 3 for Use in ar~a~
where electricity for the tes~ing apparatus 10 is not readily ¦ available.
~0 Ij 2L !I The ~triking mechanis~ 14 and the sensor 20 should be ¦ pl~ced near one end 50 o~ the ~ope 12. This simplifies ! analysis oY tests results because ~ wa~e approaGhes and then is reflected by the end 50 of the rop~ 12 closest ~o t~e sensor 2~ i Z0. These waves will p~ss the sensor 20 a very shor~ tim~
2~ 1 apart. ~hereore, the two passages appear, and can be treated 27 as a single wave for p~rposes of TIV wave n~ethod.
28 ¦ For simplici~y~s sake, the vibrational ~aves ~reated by 29 ~ the impact of the ~trikin~ mecha~ism 14 will be ~eferred ~o as 30 1 a sLngle wave in the following dis~ussion.
51 1 Referring in ~ombination to Fi~re~ 1, 3, and 4, when 32 ~, 12 5.~,`` 1 I
1 ! test is conduc~ed ~ith the ~esting apparatus 10, -~he rope 12 is a ¦, struck by the striking mechanism 14, and a vibra~ional wave is 3 ll propagated fro~ the point of i~pact. ~s the incideh~ wave ~ reaches an end 50 of the ~ope 12, it is reflected and travels S towards the ~pposite end 50 where it is again r~lected, ~his ~ cycle continues until th~ energy in the rope 12 is completely 7 ~ dissipat~d, A flaw 52 in ~he rope 12 also re~lects vibrati~nal waves, but to a lesser ex~ent t~lan ~he rope's 12 ends ~0.
9 ¦ TherP~ore, wave~ reflected by the flaw 5~ will have a lesser amplitude than waves re~lecte~ by th~ rope's ends 50. Flaw-eflected waves appear, in ~ime, between en~-re~lected waves b~cause f~aw-re~lected waves travel a shor~er distance than 13 ~I end-reflected waves.
I
14 1 As disau~sed abo~e, the sensor 20 will produce an 16 electrical signal in response to each vibrational wave of de~ectable amplitude which passes it. Each ele¢trical signal ¦ will have an amplitude proportional to the ~pli~ud~ o~ its respec~ive vibrational wave. S~gnals from an ~nd-re~lec~d ¦ wave ~11, like the wave itself, ha~e a larger amplitude than .¦ signals reflectin~ ~la~-~eflected wa~es. Flaws which are large ~i enough ~o pro~ide re~lected w~ves of measu~able amplitude are il re~erred to as "discrete flaws."
! Flaws which are too small to reflect such Waves are .! referred to as nnon-disc~e~e flaws" (not shown), ~hîle not ind1vidually detectable, the presence o~ non-discrete flaw~ may !! be recognized by me~hods which will be cliscussed hereina~ter.
xr l Referxing ~o Figure 4, a discrete flaw is indicate~ in the 1~ oscilloscope display ~a a~ a low amplitude ~law signal 54 intervenlng higher amplitude end signals 56. When a ~law . signal 54 does appear, calculations Inay be conducted to locate ~ ' the discrete flaw 52 ~shown in Figure 3) which it represen~.
3~ 13 !
i. I
ll 1 i I ~eferring ag~in to Figure 4, the pulse signal 55 i~ ~e ~ wav~ directly resul~ing from the imp~c~ ~rom the striking 4 ' ~.echanism 14, and may be t~ea~ed as ~n end signal 56.
6 The position of ea~h discrete ~law 52, the tension on ~he 6 rope, and the presence of non~di~cre~e ~law~ (hO~ shown) are 7 determined by formulae, one or more of whioh ~eguire the 8 ~ollowing var~ables whiGh may he derived rom the os~illosoope ! display 38-~ r ~ the time lnterval between ad~acent end signals 12 ' 56.
15 ! t~ ~ the time interval between an end signal 56 and ll the next subsequent ~law signal 54.
14 ',j 5 I Pi = the amplitude of an end sig~al 56 at point i.
¦¦ Pj ~ the ampli~ude o an end signal 56 at poin~ ;.
17 !I LLj = the ~raveliny distance of the wave between the 1~ two end signals shown by amplitudes Pi and P~.
;l 9 '¦ tr and t~ are determined simply by measuring the number o~
~ 'I time units between two adjacent end si~nals S6 as ind~cated by 21 ,I the x axis scale 42 ln the oscilloscope display 3B.
2~ ii Pi and Pj are determlned by resp~c~lvely mea~uring end ~3 i; signal~ 56 at poin~ 1 and ~ on th~ di~play 38 o~ the ~4 ii oscillo~cope 36 by referen~e ~o ~h~ y-axis 4 o . ~he at~enua~ion ~5, coef~ nt ~rmul~ tto be dis~usses he~eina~ter) in whi~h 2~ j these vaxiabl~ are used re~uires that Pi ~ Pj~
27 1 ~ij may be derivad by multiply~ng the leng~h (L) o~ the 28 1 rope 12 by twi~e the number of intervals between suc~s3slve e~
~9 si~nals 56 shown be~ween poin~s Pi and Pj on the di~play 3~.
The ~ollowing ~wo v~riables which are required by one or S~ !1 14 ll ~ 9~6~3~
2 m~re of the tran~ver~e impul~e vibr~tlonal wavQ method formulae must be independently determined;
L = th~ leng~h of the rope being t~sted.
= the mass per uni~ length o~ the rope being 7 ~e~ted.
I~ the entire length of a ~ope 12 may be vi~wed, as in 9 l i Fiqure 3 wherein ~he rope 12 is used ag ~ gUy Wire~ ~he length (~) may be determined by triangu~ation. If t~langulatlon is 1 1.
not possi~le, t~e length (L) o~ the rope 12 mu~t be de~2rmined 12 , 13 ' by other means -- eithe~ by dire~t measurement, or ~y referen~e ' to ~lueprints, e~c.
: 14 j The ma~s per unit length (C) o ~h~ ~ope 12 may be : l6 ~ a~quired ~rom the manu~a~turer of ~he rope 12, o~ may be 1~
l determined by analysis o~ a rope sample (no~ shvwn) li~e the 17 j : Ij particular rope 12 which i~ ~o be tested.
~8 . ~aria~lPq WhiCh are derived ~y ~he me~hod ~o~ulae are as ~9 !
:j ~ollow~:
~1 1 : ,¦ D = the distance of a flaw fro~ the end 50 of the ~2 '~
~,i; rope 12 closest to the sensor 20.
v = propaga~ion ~eloci~y of vibrational waYes ~4 ;
¦¦ through ~he rope 12~
! T - ~he tensile load on the rope 12.
2~ !
¦ alpha- the attenuation coeff icien-t oE vibrational wave in the ~ope 12.
~8 ~i : ' The ~is~n~e (D) o~ a discrete flaw 52 from the~ end 50 o~
51 , ~r~
i ~.29~6~
the rope 12 nearest the sensor 2 0 may be ne~rly approximated aoc~ording to the following~ formula:
;S
4 D -- L(tf/~r) ~;
The flaw location aspect of the me~hod permits substantial ~me 7 savings in loc~ing a known di~rete flaw 52 for determining 8 the need fo~ the rope~s 12 replacement. ~his i.s a substantial 9 ¦ improvement over existing rope testing ~.etho~ Which require 0 1 passing the ~esting apparatus over the entirety of the rope 12 to dete~ and te locate a ~law 52.
~2 il During the time between two successive end signals 5~, and 13 j: consequently between two successi~e p~3~a~es of an ~nd 14 refleGted vibrational waves, the wave wlll have travelled the length ~) of the rope 1~ twice. The~efore,:the propa~ation : lg ¦ velocity (v) o~ vibratlonal waves in the rope 12 is determined b~ the following fo~mula:
8~
~ = 2L/tr ~ ~ 20: il ~1 !IPropagation velocity (v) i5 a function o~ the tension (T~
, ~ a2 i on the rope 12 according to the following formula;
~ 23~
v -- ( Tf C ) 1/ 2 ~ I!
2~ !1 ¦The formula ~r calculating tensile load (T) when propagation i a7 ~v~3locity ~v) is known becomes:
28 !
29 T - ~:v2 ;~ 30 ~: :3L ¦1 5irice ~h~ t~sting apparatus 10 permi'cs cal~ula~ing th~
; S2 i, 1 ~ : 11 ~ !l , j.
1 ¦ propagation velocity (v) kno~ing only the rope's 12 length (L) 2 1 and ~he cons~ant ~C,~ this formula of the ~ethod permits the 3 very simple determination of the tensile load on ~ rope 12.
4 Such ease of calculation has obvious pract~cal sa~ety ~ implications.
I ~ A~ briefly alluded to above, transverse impulse . vibrational wave metllod includes steps Which, in some instances, provide an indicia of non-discrete flaws (not shown) , in the rope 12. This aspect of the method is based upon the 10 ~ fact that the rate at Whic~ energy in a vibra~ing rope 1~ is 11 dissipated is directly propor~ional to the populatioh of flaws 1~ ' in a rope 12.
13 Flaws, whether discrete or non-discrete, interrupt the .¦ propagation of vibrational waves th~ough -the rope 12, and Il energy ~s thereby dissipated more rapidly than in a rope havinq ¦¦ fewer ox no flaws. The rate of ene~gy dissipation in the rope ~ is shown by an a~tenuation coefficient (alpha~. ~he 1 ' attenuation coefficient is calculated by ~he following for~ula~
19~:
alpha = ~0 1~ ( )/Lij ~1 2 11 If the tested rop~ 12 shows a higher a~t~nuation co~fficient 23 ' talpha) than a ~ontrol rop~ (no~ shown) known to b2 flawle~s, 1 ~4 !! ~laws in the r~pe 12 are indicated.
As indicated abo~e, the v~iables necessary for ~B ~I calcula~ing the a~tenuation c~e~ficient ara easily derive~ ~rom 27 ! the dispIay 3~ of ~h~ os~illos~ope 36.
28 While t~ere is no way to distingui~h bet.ween discrete 29 flaws 52 and non-discrete flaws ~not shown) by calculating the 30 1 attenuation coeffici~n~, ~here is considerable value in making 1 Il the cal~ulation. This is pa~ticularly so when no discretQ
3~ I; 17 l ~z~6~
I
l j flaws S~ are de~e~ed. A high variance in the at~enuation 2 1 ooefficient o~ the rope 12 from that of a control rope (not 3 shown) would, in such a case, indicate a high n~n-discrete flaw 4 ¦ (not shown) population. such a rope sho~ld be investigated 5 1 ~urther.
~ I E~e~ when discrete flaws 52 a~e de.~ec~ed, an experien~ed q u~er ~ay be able to recognize that the attenUAtiOn c~ef~iclent 8 ¦ f~r the rop~ 12 t~ not in line with t~e exp~c~ed value, i~
9 1 light of the severity, or la~k thereo~ of the known discret~
lO , ~laws 5Z. Such a disparity would be an indication of ~
l~ significant non-di~c~ete flaw popula~ion in add~ion to the 12 '! known discrete flaw~ 5 13 ~! ~e~erring again to Figures 1 and 4, as is apparent ~ro~
! the above discussion, proper analysis o~ the ~ignals ~om ~he i! sensor 20 requires precise measurements oP time interval~
I between end signals 56 an~ flaw signals 54 and of the rela~ive ¦ amplitudes o~ adjacent end signals 56. C~lculations based upon ! the mea~red amplitudes and intervals are also requi~ed.
! There~ore, wh~l~ not neces~ar~v t~ prac~ic~ transverse impul~e : ,. vibrational wave method, a computer ~8 for automa~ing . measuremen~s and calculatiQns is desirable.
~ he compu~er 58 should be programed and equipped for the ~., following tasks:
24 1) ~o re.ceive and store data ~rom t~e digitiziny oscilloscopc 36 representing ~he amplitude o~ and 2~ time intervals between the signa~ initially produced 27 I by the sensor 20;
2~ ¦ 2) To derive comparatlve amplitude~ of the signals;
3~ ~o mea~ure time between adjacen~ end signals 56, as ~ well as between a ~law ~ignal 54 and an adjacent end 31 `
469~
1 signal s6;
I ~ 4) To receive input of th~ rope's 12 lenyth rrOm the 3 user of the testing apparatus 10;
4 S) To receive input of the constan~ C for t~e particular rope 12 being tested, which cons~ant, when multiplie~
~ by the propagation velocity squared, yields the : i tensio~ on the rope 12, and ~o make the calculat~on;
7 ~) To divide the time be~ween the flaw signal 54 and the ~ ¦ adj~cen~ end signal 56 by the time betwesn adiacent 10 1 end ~ignals 5~ and to multiply the yuotien~ by the 11 rope's 12 length to calculate the discrete flaw's 52 a I po~ition on the rope;
~:13 7) To measure a di~ference in ampli~de between two 14 1 adjacent on~ sig~als 5~ and calculate the ~ttenuatio~
:~ lG ¦ coefficient for the rope 12; and ¦ 8) Most impor~a~tly, to provide the derived in~ormation ~17 ¦ ~ in a useful f~rmat.
¦ Fo~ producing permanent tes~ records, and particularly ~r ~, :
preparing :graph~al depictions o~ th~: testing apparatu3' 10 measurements a~: shown in Figure 4, a recorder ar grap~iag ~ ;prlnter 60 shauld ~e attached to ~he ~omp~er ~8.
The :testing apparatu~ 10 and fo~mulae juSt discussed ~ 2~ provide a method o~ tes~ing cable, syn~hetic rope, and m~tal :z~ str~nd~whlch h~s~not ~een; previously known. No presently 2~ known tes~ing apparatus l~or method is ~pplicable to 2~ ferromagnetlc and:~non-ferromagnetic mat~rials, while at ~h~
7~1 same t ime~ permittlng full-léngth testing ~rom a sinql~ location :28~¦ ~:~on a cable, rop~, or ~trand.
29~! ~ ~he abili~y to Ce~t syn~hetic ropes mad~ of such ma~erials as nylon and ~VL~R~ will enable th~ use of the~e ropes ~or 3~ i 58 ~
:
~9~69g 1 applications previously reserved to metallic cahles because of 2 inade~uate testihg procedures . The ahil i~y to tes~ the f~
3 length o ;~ cable, rope, or ~;trand will greatly reduce the ti~e 4 and expense i~lvolved in testing ~;uch ~hings as elevator ca~les, ~ antenna guy wires, crane support cables, and the like.
12 !¦
lJ~ 1i 1~
18 i ~9 'i 22 ., -~4 2~ 1.
~ 28 !1 29 I~
` ~'.~
! I
S2 ', 1~ 2Q
14 ',j 5 I Pi = the amplitude of an end sig~al 56 at point i.
¦¦ Pj ~ the ampli~ude o an end signal 56 at poin~ ;.
17 !I LLj = the ~raveliny distance of the wave between the 1~ two end signals shown by amplitudes Pi and P~.
;l 9 '¦ tr and t~ are determined simply by measuring the number o~
~ 'I time units between two adjacent end si~nals S6 as ind~cated by 21 ,I the x axis scale 42 ln the oscilloscope display 3B.
2~ ii Pi and Pj are determlned by resp~c~lvely mea~uring end ~3 i; signal~ 56 at poin~ 1 and ~ on th~ di~play 38 o~ the ~4 ii oscillo~cope 36 by referen~e ~o ~h~ y-axis 4 o . ~he at~enua~ion ~5, coef~ nt ~rmul~ tto be dis~usses he~eina~ter) in whi~h 2~ j these vaxiabl~ are used re~uires that Pi ~ Pj~
27 1 ~ij may be derivad by multiply~ng the leng~h (L) o~ the 28 1 rope 12 by twi~e the number of intervals between suc~s3slve e~
~9 si~nals 56 shown be~ween poin~s Pi and Pj on the di~play 3~.
The ~ollowing ~wo v~riables which are required by one or S~ !1 14 ll ~ 9~6~3~
2 m~re of the tran~ver~e impul~e vibr~tlonal wavQ method formulae must be independently determined;
L = th~ leng~h of the rope being t~sted.
= the mass per uni~ length o~ the rope being 7 ~e~ted.
I~ the entire length of a ~ope 12 may be vi~wed, as in 9 l i Fiqure 3 wherein ~he rope 12 is used ag ~ gUy Wire~ ~he length (~) may be determined by triangu~ation. If t~langulatlon is 1 1.
not possi~le, t~e length (L) o~ the rope 12 mu~t be de~2rmined 12 , 13 ' by other means -- eithe~ by dire~t measurement, or ~y referen~e ' to ~lueprints, e~c.
: 14 j The ma~s per unit length (C) o ~h~ ~ope 12 may be : l6 ~ a~quired ~rom the manu~a~turer of ~he rope 12, o~ may be 1~
l determined by analysis o~ a rope sample (no~ shvwn) li~e the 17 j : Ij particular rope 12 which i~ ~o be tested.
~8 . ~aria~lPq WhiCh are derived ~y ~he me~hod ~o~ulae are as ~9 !
:j ~ollow~:
~1 1 : ,¦ D = the distance of a flaw fro~ the end 50 of the ~2 '~
~,i; rope 12 closest to the sensor 20.
v = propaga~ion ~eloci~y of vibrational waYes ~4 ;
¦¦ through ~he rope 12~
! T - ~he tensile load on the rope 12.
2~ !
¦ alpha- the attenuation coeff icien-t oE vibrational wave in the ~ope 12.
~8 ~i : ' The ~is~n~e (D) o~ a discrete flaw 52 from the~ end 50 o~
51 , ~r~
i ~.29~6~
the rope 12 nearest the sensor 2 0 may be ne~rly approximated aoc~ording to the following~ formula:
;S
4 D -- L(tf/~r) ~;
The flaw location aspect of the me~hod permits substantial ~me 7 savings in loc~ing a known di~rete flaw 52 for determining 8 the need fo~ the rope~s 12 replacement. ~his i.s a substantial 9 ¦ improvement over existing rope testing ~.etho~ Which require 0 1 passing the ~esting apparatus over the entirety of the rope 12 to dete~ and te locate a ~law 52.
~2 il During the time between two successive end signals 5~, and 13 j: consequently between two successi~e p~3~a~es of an ~nd 14 refleGted vibrational waves, the wave wlll have travelled the length ~) of the rope 1~ twice. The~efore,:the propa~ation : lg ¦ velocity (v) o~ vibratlonal waves in the rope 12 is determined b~ the following fo~mula:
8~
~ = 2L/tr ~ ~ 20: il ~1 !IPropagation velocity (v) i5 a function o~ the tension (T~
, ~ a2 i on the rope 12 according to the following formula;
~ 23~
v -- ( Tf C ) 1/ 2 ~ I!
2~ !1 ¦The formula ~r calculating tensile load (T) when propagation i a7 ~v~3locity ~v) is known becomes:
28 !
29 T - ~:v2 ;~ 30 ~: :3L ¦1 5irice ~h~ t~sting apparatus 10 permi'cs cal~ula~ing th~
; S2 i, 1 ~ : 11 ~ !l , j.
1 ¦ propagation velocity (v) kno~ing only the rope's 12 length (L) 2 1 and ~he cons~ant ~C,~ this formula of the ~ethod permits the 3 very simple determination of the tensile load on ~ rope 12.
4 Such ease of calculation has obvious pract~cal sa~ety ~ implications.
I ~ A~ briefly alluded to above, transverse impulse . vibrational wave metllod includes steps Which, in some instances, provide an indicia of non-discrete flaws (not shown) , in the rope 12. This aspect of the method is based upon the 10 ~ fact that the rate at Whic~ energy in a vibra~ing rope 1~ is 11 dissipated is directly propor~ional to the populatioh of flaws 1~ ' in a rope 12.
13 Flaws, whether discrete or non-discrete, interrupt the .¦ propagation of vibrational waves th~ough -the rope 12, and Il energy ~s thereby dissipated more rapidly than in a rope havinq ¦¦ fewer ox no flaws. The rate of ene~gy dissipation in the rope ~ is shown by an a~tenuation coefficient (alpha~. ~he 1 ' attenuation coefficient is calculated by ~he following for~ula~
19~:
alpha = ~0 1~ ( )/Lij ~1 2 11 If the tested rop~ 12 shows a higher a~t~nuation co~fficient 23 ' talpha) than a ~ontrol rop~ (no~ shown) known to b2 flawle~s, 1 ~4 !! ~laws in the r~pe 12 are indicated.
As indicated abo~e, the v~iables necessary for ~B ~I calcula~ing the a~tenuation c~e~ficient ara easily derive~ ~rom 27 ! the dispIay 3~ of ~h~ os~illos~ope 36.
28 While t~ere is no way to distingui~h bet.ween discrete 29 flaws 52 and non-discrete flaws ~not shown) by calculating the 30 1 attenuation coeffici~n~, ~here is considerable value in making 1 Il the cal~ulation. This is pa~ticularly so when no discretQ
3~ I; 17 l ~z~6~
I
l j flaws S~ are de~e~ed. A high variance in the at~enuation 2 1 ooefficient o~ the rope 12 from that of a control rope (not 3 shown) would, in such a case, indicate a high n~n-discrete flaw 4 ¦ (not shown) population. such a rope sho~ld be investigated 5 1 ~urther.
~ I E~e~ when discrete flaws 52 a~e de.~ec~ed, an experien~ed q u~er ~ay be able to recognize that the attenUAtiOn c~ef~iclent 8 ¦ f~r the rop~ 12 t~ not in line with t~e exp~c~ed value, i~
9 1 light of the severity, or la~k thereo~ of the known discret~
lO , ~laws 5Z. Such a disparity would be an indication of ~
l~ significant non-di~c~ete flaw popula~ion in add~ion to the 12 '! known discrete flaw~ 5 13 ~! ~e~erring again to Figures 1 and 4, as is apparent ~ro~
! the above discussion, proper analysis o~ the ~ignals ~om ~he i! sensor 20 requires precise measurements oP time interval~
I between end signals 56 an~ flaw signals 54 and of the rela~ive ¦ amplitudes o~ adjacent end signals 56. C~lculations based upon ! the mea~red amplitudes and intervals are also requi~ed.
! There~ore, wh~l~ not neces~ar~v t~ prac~ic~ transverse impul~e : ,. vibrational wave method, a computer ~8 for automa~ing . measuremen~s and calculatiQns is desirable.
~ he compu~er 58 should be programed and equipped for the ~., following tasks:
24 1) ~o re.ceive and store data ~rom t~e digitiziny oscilloscopc 36 representing ~he amplitude o~ and 2~ time intervals between the signa~ initially produced 27 I by the sensor 20;
2~ ¦ 2) To derive comparatlve amplitude~ of the signals;
3~ ~o mea~ure time between adjacen~ end signals 56, as ~ well as between a ~law ~ignal 54 and an adjacent end 31 `
469~
1 signal s6;
I ~ 4) To receive input of th~ rope's 12 lenyth rrOm the 3 user of the testing apparatus 10;
4 S) To receive input of the constan~ C for t~e particular rope 12 being tested, which cons~ant, when multiplie~
~ by the propagation velocity squared, yields the : i tensio~ on the rope 12, and ~o make the calculat~on;
7 ~) To divide the time be~ween the flaw signal 54 and the ~ ¦ adj~cen~ end signal 56 by the time betwesn adiacent 10 1 end ~ignals 5~ and to multiply the yuotien~ by the 11 rope's 12 length to calculate the discrete flaw's 52 a I po~ition on the rope;
~:13 7) To measure a di~ference in ampli~de between two 14 1 adjacent on~ sig~als 5~ and calculate the ~ttenuatio~
:~ lG ¦ coefficient for the rope 12; and ¦ 8) Most impor~a~tly, to provide the derived in~ormation ~17 ¦ ~ in a useful f~rmat.
¦ Fo~ producing permanent tes~ records, and particularly ~r ~, :
preparing :graph~al depictions o~ th~: testing apparatu3' 10 measurements a~: shown in Figure 4, a recorder ar grap~iag ~ ;prlnter 60 shauld ~e attached to ~he ~omp~er ~8.
The :testing apparatu~ 10 and fo~mulae juSt discussed ~ 2~ provide a method o~ tes~ing cable, syn~hetic rope, and m~tal :z~ str~nd~whlch h~s~not ~een; previously known. No presently 2~ known tes~ing apparatus l~or method is ~pplicable to 2~ ferromagnetlc and:~non-ferromagnetic mat~rials, while at ~h~
7~1 same t ime~ permittlng full-léngth testing ~rom a sinql~ location :28~¦ ~:~on a cable, rop~, or ~trand.
29~! ~ ~he abili~y to Ce~t syn~hetic ropes mad~ of such ma~erials as nylon and ~VL~R~ will enable th~ use of the~e ropes ~or 3~ i 58 ~
:
~9~69g 1 applications previously reserved to metallic cahles because of 2 inade~uate testihg procedures . The ahil i~y to tes~ the f~
3 length o ;~ cable, rope, or ~;trand will greatly reduce the ti~e 4 and expense i~lvolved in testing ~;uch ~hings as elevator ca~les, ~ antenna guy wires, crane support cables, and the like.
12 !¦
lJ~ 1i 1~
18 i ~9 'i 22 ., -~4 2~ 1.
~ 28 !1 29 I~
` ~'.~
! I
S2 ', 1~ 2Q
Claims (11)
1. A non-destructive method for evaluating a rope under tension comprising the steps of:
striking said rope at a single point with a force transverse to its length, said force sufficient to produce an incident vibrational wave in said rope, said incident vibrational wave travelling said length of said rope and producing flaw-reflected waves upon encountering a flaw in said rope and producing end-reflected waves upon encountering an end of said rope;
sensing said flaw-reflected waves and said end-reflected waves in said rope at a single point with sensor means adjacent to said rope, said sensor means producing electrical signals having amplitudes directly proportional to amplitudes of said flaw-reflected waves and said end-reflected waves, said electrical signals having a time distribution directly related to a time distribution of said flaw-reflected waves and said end-reflected waves;
receiving and processing said electrical signals from said sensor means whereby said electrical signals may be depicted graphically by display means in amplitude versus time arrangement;
displaying said amplitude and said time distribution of said electrical signals with said display means, said amplitude and said time distribution of said electrical signals representative of said amplitude and said time distribution of said flaw-reflected waves and said end-reflected waves;
monitoring said display means during and after striking said rope to determine said amplitude and said time distribution of said electrical signals produced by said sensor means; and detecting a sequential pattern of low amplitude electrical signals caused by said flaw-reflected waves intervening higher amplitude electrical signals caused by said end-reflected waves.
striking said rope at a single point with a force transverse to its length, said force sufficient to produce an incident vibrational wave in said rope, said incident vibrational wave travelling said length of said rope and producing flaw-reflected waves upon encountering a flaw in said rope and producing end-reflected waves upon encountering an end of said rope;
sensing said flaw-reflected waves and said end-reflected waves in said rope at a single point with sensor means adjacent to said rope, said sensor means producing electrical signals having amplitudes directly proportional to amplitudes of said flaw-reflected waves and said end-reflected waves, said electrical signals having a time distribution directly related to a time distribution of said flaw-reflected waves and said end-reflected waves;
receiving and processing said electrical signals from said sensor means whereby said electrical signals may be depicted graphically by display means in amplitude versus time arrangement;
displaying said amplitude and said time distribution of said electrical signals with said display means, said amplitude and said time distribution of said electrical signals representative of said amplitude and said time distribution of said flaw-reflected waves and said end-reflected waves;
monitoring said display means during and after striking said rope to determine said amplitude and said time distribution of said electrical signals produced by said sensor means; and detecting a sequential pattern of low amplitude electrical signals caused by said flaw-reflected waves intervening higher amplitude electrical signals caused by said end-reflected waves.
2. The method of Claim 1 further comprising the steps of:
measuring an end-to-end time (tr), between a first said end-reflected wave and a next said end-reflected wave;
calculating propagation velocity of said end-reflected waves and said flaw-reflected waves in said rope by a propagation velocity formula v = 2L/tr where v represents said propagation velocity, L
represents said length of said rope, tr represents said end-to-end time; and calculating tension on said rope by a rope tension formula T = Cv2 where T represents said tension on said rope, C
represents mass per unit length of said rope, v represents said propagation velocity.
measuring an end-to-end time (tr), between a first said end-reflected wave and a next said end-reflected wave;
calculating propagation velocity of said end-reflected waves and said flaw-reflected waves in said rope by a propagation velocity formula v = 2L/tr where v represents said propagation velocity, L
represents said length of said rope, tr represents said end-to-end time; and calculating tension on said rope by a rope tension formula T = Cv2 where T represents said tension on said rope, C
represents mass per unit length of said rope, v represents said propagation velocity.
3. The method of Claim 2 further comprising the steps of:
measuring a flaw-to-end time (tf), between a first said flaw-reflected wave and a next said end-reflected wave; and calculating a position of a flaw indicated by said flaw-reflected waves by a flaw position formula D = L(tf/tr) where D represents distance of said flaw from an end of said rope closest to said sensor means, L
represents said length of said rope, tr represents said end-to-end time, tf represents said flaw-to-end time.
measuring a flaw-to-end time (tf), between a first said flaw-reflected wave and a next said end-reflected wave; and calculating a position of a flaw indicated by said flaw-reflected waves by a flaw position formula D = L(tf/tr) where D represents distance of said flaw from an end of said rope closest to said sensor means, L
represents said length of said rope, tr represents said end-to-end time, tf represents said flaw-to-end time.
4. The method of Claim 3 further comprising the steps of:
measuring amplitude (Pi) of a first said end-reflected wave;
measuring amplitude (Pj) of a next said end-reflected wave;
measuring distance traveled (Lij) by said end-reflected waves during a time interval between said first end-reflected wave and said next end-reflected wave;
and calculating an attenuation coefficient for said rope whereby overall flaw population in said rope may be determined by an attenuation coefficient formula alpha = -20 log (Pj/Pi)/Lij where alpha represents said attenuation coefficient, Pi represents said amplitude of said first end-reflected wave, Pj represents said amplitude of said next end-reflected wave, Lij represents said distance travelled by said end-reflected waves during said time interval between said first end-reflected wave and said next end-reflected wave, log indicates a logarithmic function operation.
measuring amplitude (Pi) of a first said end-reflected wave;
measuring amplitude (Pj) of a next said end-reflected wave;
measuring distance traveled (Lij) by said end-reflected waves during a time interval between said first end-reflected wave and said next end-reflected wave;
and calculating an attenuation coefficient for said rope whereby overall flaw population in said rope may be determined by an attenuation coefficient formula alpha = -20 log (Pj/Pi)/Lij where alpha represents said attenuation coefficient, Pi represents said amplitude of said first end-reflected wave, Pj represents said amplitude of said next end-reflected wave, Lij represents said distance travelled by said end-reflected waves during said time interval between said first end-reflected wave and said next end-reflected wave, log indicates a logarithmic function operation.
5. The method of Claim 4 further comprising the step of connecting computing means to said display means, said computing means receiving data representing said amplitude of said flaw-reflected waves and said end-reflected waves and said time distribution of said flaw-reflected waves and said end-reflected waves; said computing means receiving input of said length of said rope and said mass per unit length of said rope; said computing means deriving said tr, said tf, said Pj, said Pi, and said Lij from said data; said computing means calculating said flaw position by said flaw position forumla, said tension on said rope by said tension formula, and said attenuation coefficient by said attenuation coefficient formula.
6. A non-destructive method for evaluating a rope under tension comprising the steps of:
striking said rope at a single point with a force transverse to its length, said force sufficient to produce an incident vibrational wave in said rope, said incident vibrational wave travelling said length of said rope and producing flaw-reflected waves upon encountering a flaw in said rope and producing end-reflected waves upon encountering an end of said rope;
sensing said flaw-reflected waves and said end-reflected waves in said rope at a single point with sensor means-adjacent to said rope, said sensor means producing electrical signals having amplitudes directly proportional to amplitudes of said flaw-reflected waves and said end-reflected waves, said electrical signals having a time distribution directly related to a time distribution of said flaw-reflected waves and said end-reflected waves;
receiving and processing said electrical signals from said sensor means whereby said electrical signals may be depicted graphically by display means in amplitude versus time arrangement;
displaying said amplitude and said time distribution of said electrical signals with said display means, said amplitude and said time distribution of said electrical signals representative of said amplitude and said time distribution of said flaw-reflected waves and said end-reflected waves;
monitoring said display means during and after striking said rope to determine said amplitude and said time distribution of said electrical signals produced by said sensor means;
detecting a sequential pattern of low amplitude electrical signals caused by said flaw-reflected waves intervening higher amplitude electrical signals caused by said end-reflected waves;
measuring an end-to-end time (tr) between a first said end-reflected wave and a next said end-reflected wave;
calculating propagation velocity of said end-reflected waves and said flaw-reflected waves in said rope by a propagation velocity formula v = 2L/tr where v represents said propagation velocity, L
represents said length of said rope and tr represents said end-to-end time;
calculating tension on said rope by a rope tension formula T = Cv2 where T represents said tension on said rope, C
represents mass per unit length of said rope and v represents said propagation velocity;
measuring a flaw-to-end time (tf) between a first said flaw-reflected wave and a next said end-reflected wave;
calculating a position of a flaw indicated by said flaw-reflected waves by a flaw position formula D = L(tf/tr) where D represents distance of said flaw from an end of said rope closest to said sensor means, L
represents said length of said rope, tr represents said end-to-end time and tf represents said flaw-to-end time;
measuring amplitude (Pi) of a first said end-reflected wave;
measuring amplitude (Pj) of a next said end-reflected wave;
measuring distance traveled (Lij) by said end-reflected waves during a time interval between said first end-reflected wave and said next end-reflected wave;
and calculating an attenuation coefficient for said rope whereby overall flaw population in said rope may be determined by an attenuation coefficient formula alpha = -20 log (Pj/Pi)/Lij where alpha represents said attenuation coefficient, Pi represents said amplitude of said first end-reflected wave, Pj represents said amplitude of said next end-reflected wave, Lij represents said distance travelled by said end-reflected waves during said time interval between said first end-reflected wave and said next end-reflected wave and log indicates a logarithmic function operation.
striking said rope at a single point with a force transverse to its length, said force sufficient to produce an incident vibrational wave in said rope, said incident vibrational wave travelling said length of said rope and producing flaw-reflected waves upon encountering a flaw in said rope and producing end-reflected waves upon encountering an end of said rope;
sensing said flaw-reflected waves and said end-reflected waves in said rope at a single point with sensor means-adjacent to said rope, said sensor means producing electrical signals having amplitudes directly proportional to amplitudes of said flaw-reflected waves and said end-reflected waves, said electrical signals having a time distribution directly related to a time distribution of said flaw-reflected waves and said end-reflected waves;
receiving and processing said electrical signals from said sensor means whereby said electrical signals may be depicted graphically by display means in amplitude versus time arrangement;
displaying said amplitude and said time distribution of said electrical signals with said display means, said amplitude and said time distribution of said electrical signals representative of said amplitude and said time distribution of said flaw-reflected waves and said end-reflected waves;
monitoring said display means during and after striking said rope to determine said amplitude and said time distribution of said electrical signals produced by said sensor means;
detecting a sequential pattern of low amplitude electrical signals caused by said flaw-reflected waves intervening higher amplitude electrical signals caused by said end-reflected waves;
measuring an end-to-end time (tr) between a first said end-reflected wave and a next said end-reflected wave;
calculating propagation velocity of said end-reflected waves and said flaw-reflected waves in said rope by a propagation velocity formula v = 2L/tr where v represents said propagation velocity, L
represents said length of said rope and tr represents said end-to-end time;
calculating tension on said rope by a rope tension formula T = Cv2 where T represents said tension on said rope, C
represents mass per unit length of said rope and v represents said propagation velocity;
measuring a flaw-to-end time (tf) between a first said flaw-reflected wave and a next said end-reflected wave;
calculating a position of a flaw indicated by said flaw-reflected waves by a flaw position formula D = L(tf/tr) where D represents distance of said flaw from an end of said rope closest to said sensor means, L
represents said length of said rope, tr represents said end-to-end time and tf represents said flaw-to-end time;
measuring amplitude (Pi) of a first said end-reflected wave;
measuring amplitude (Pj) of a next said end-reflected wave;
measuring distance traveled (Lij) by said end-reflected waves during a time interval between said first end-reflected wave and said next end-reflected wave;
and calculating an attenuation coefficient for said rope whereby overall flaw population in said rope may be determined by an attenuation coefficient formula alpha = -20 log (Pj/Pi)/Lij where alpha represents said attenuation coefficient, Pi represents said amplitude of said first end-reflected wave, Pj represents said amplitude of said next end-reflected wave, Lij represents said distance travelled by said end-reflected waves during said time interval between said first end-reflected wave and said next end-reflected wave and log indicates a logarithmic function operation.
7. The method of Claim 6 further comprising the step of connecting computing means to said display means, said computing means receiving data representing said amplitude of said flaw-reflected waves and said end-reflected waves and said time distribution of said flaw-reflected waves and said end-reflected waves; said computing means receiving input of said length of said rope and said mass per unit length of said rope; said computing means deriving said tr, said tf, said Pj, said Pi, and said Lij from said data; said computing means calculating said flaw position by said flaw position formula, said tension on said rope by said tension formula, and said attenuation coefficient by said attenuation coefficient formula.
8. An apparatus for testing a rope under tension comprising:
means for striking said rope transversely at a single point to produce an incident vibrational wave along said rope, said incident vibrational wave producing flaw-reflected waves upon encountering a flaw in said rope and producing end-reflected waves upon encountering an end of said rope;
sensor means adjacent said rope for detecting said flaw-reflected waves and said end-reflected waves in said rope at a single point, said sensor means producing an electrical signal having amplitudes and a time distribution proportional to said flaw-reflected waves and said end-reflected waves;
means for amplifying said amplitudes of said electrical signal to detectable and measurable levels; and means for analyzing said electrical signal, said analyzing means detecting and measuring said amplitudes and said time distribution of said electrical signal and discriminating a first portion of said electrical signal indicative of said flaw-reflected waves from a second portion of said electrical signal indicative of said end-reflected waves, so as to locate said flaw.
means for striking said rope transversely at a single point to produce an incident vibrational wave along said rope, said incident vibrational wave producing flaw-reflected waves upon encountering a flaw in said rope and producing end-reflected waves upon encountering an end of said rope;
sensor means adjacent said rope for detecting said flaw-reflected waves and said end-reflected waves in said rope at a single point, said sensor means producing an electrical signal having amplitudes and a time distribution proportional to said flaw-reflected waves and said end-reflected waves;
means for amplifying said amplitudes of said electrical signal to detectable and measurable levels; and means for analyzing said electrical signal, said analyzing means detecting and measuring said amplitudes and said time distribution of said electrical signal and discriminating a first portion of said electrical signal indicative of said flaw-reflected waves from a second portion of said electrical signal indicative of said end-reflected waves, so as to locate said flaw.
9. The apparatus for testing a rope as given in Claim 8 wherein said analyzing means includes a digitizing oscilloscope for generating a visually perceptible indication of said electrical signal.
10. The apparatus for testing rope as given in Claim 9 wherein said analyzing means further includes electronic data processing means, said electronic data processing means receiving output data from said digitizing oscilloscope, said electronic data processing means calculating from said output data a distance from said end of said rope to said flaw.
11. The apparatus for testing a rope as given in Claim 8 including between said amplifying means and said analyzing means a signal conditioner to eliminate unwanted noise from said electrical signal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US12276387A | 1987-11-19 | 1987-11-19 | |
| US122,763 | 1987-11-19 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1294699C true CA1294699C (en) | 1992-01-21 |
Family
ID=22404623
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000583653A Expired - Fee Related CA1294699C (en) | 1987-11-19 | 1988-11-21 | Non-destructive evaluation of ropes by using transverse impulse vibrational wave method |
Country Status (3)
| Country | Link |
|---|---|
| EP (1) | EP0429446A4 (en) |
| CA (1) | CA1294699C (en) |
| WO (1) | WO1989004960A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5024091A (en) * | 1986-03-25 | 1991-06-18 | Washington State University Research Foundation, Inc. | Non-destructive evaluation of structural members |
| DE19531858B4 (en) * | 1995-08-30 | 2005-06-09 | Deutsche Telekom Ag | Measuring method for guy ropes |
| WO2010129701A2 (en) | 2009-05-05 | 2010-11-11 | Actuant Corporation | Non-contact acoustic signal propagation property evaluation of synthetic fiber rope |
| ES2388295B2 (en) * | 2010-07-20 | 2013-02-14 | Manuel Córdoba Escobar | SECURITY DEVICE FOR DETECTION OF DEFECTS IN METALLIC STRUCTURE CABLES. |
| CA3000694C (en) | 2015-09-30 | 2019-02-26 | Greg Zoltan Mozsgai | Non-destructive evaluation of cordage products |
| CN106841385B (en) * | 2017-01-15 | 2019-05-07 | 长沙理工大学 | Detection method based on sound-ultrasound polypropylene production pipeline powder coherent condition |
| WO2021133967A1 (en) * | 2019-12-24 | 2021-07-01 | Samson Rope Technologies | Systems and methods for evaluating characteristics of rope |
| CN113884569A (en) * | 2021-08-12 | 2022-01-04 | 洛阳百克特科技发展股份有限公司 | Steel wire rope damage detection device and method based on vibration effect |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4408285A (en) * | 1981-02-02 | 1983-10-04 | Ird Mechanalysis, Inc. | Vibration analyzing apparatus and method |
| CH656160A5 (en) * | 1982-05-18 | 1986-06-13 | Zellweger Uster Ag | METHOD AND DEVICE FOR MONITORING SINGLE LOADERS IN CABLE WIRE PROCESSES. |
| JPS5984153A (en) * | 1982-11-05 | 1984-05-15 | Sumitomo Metal Ind Ltd | Inspecting method of lining |
| US4519245A (en) * | 1983-04-05 | 1985-05-28 | Evans Herbert M | Method and apparatus for the non-destructive testing of materials |
| US4567764A (en) * | 1983-12-27 | 1986-02-04 | Combustion Engineering, Inc. | Detection of clad disbond |
-
1988
- 1988-11-21 WO PCT/US1988/004174 patent/WO1989004960A1/en not_active Application Discontinuation
- 1988-11-21 EP EP19890900031 patent/EP0429446A4/en not_active Withdrawn
- 1988-11-21 CA CA000583653A patent/CA1294699C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| EP0429446A1 (en) | 1991-06-05 |
| WO1989004960A1 (en) | 1989-06-01 |
| EP0429446A4 (en) | 1991-10-16 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4979125A (en) | Non-destructive evaluation of ropes by using transverse impulse vibrational wave method | |
| US5821430A (en) | Method and apparatus for conducting in-situ nondestructive tensile load measurements in cables and ropes | |
| US5457994A (en) | Nondestructive evaluation of non-ferromagnetic materials using magnetostrictively induced acoustic/ultrasonic waves and magnetostrictively detected acoustic emissions | |
| US5456113A (en) | Nondestructive evaluation of ferromagnetic cables and ropes using magnetostrictively induced acoustic/ultrasonic waves and magnetostrictively detected acoustic emissions | |
| EP0239537B1 (en) | Method of and apparatus for testing a wire rope | |
| US6424150B2 (en) | Magnetostrictive sensor rail inspection system | |
| US4901575A (en) | Methods and apparatus for monitoring structural members subject to transient loads | |
| US4956999A (en) | Methods and apparatus for monitoring structural members subject to transient loads | |
| US6192758B1 (en) | Structure safety inspection | |
| US20040221652A1 (en) | Transducer guided wave electromagnetic acoustic | |
| EP0845688A2 (en) | System and method for measurement, analysis and assessment of ground structures | |
| US5623421A (en) | Monitoring pressurized vessels for leaks, ruptures or hard hits | |
| CA1294699C (en) | Non-destructive evaluation of ropes by using transverse impulse vibrational wave method | |
| EP0988539B1 (en) | Method and apparatus for monitoring of tensioned cables | |
| EP2567224B1 (en) | Method and device for non-destructive material testing by means of ultrasound | |
| CA1225734A (en) | Methods and apparatus for indicating selected physical parameters in a pipeline | |
| GB2383413A (en) | Detecting rail defects using acoustic surface waves | |
| JPH0511895B2 (en) | ||
| US20210318167A1 (en) | Distributed acoustic sensing based natural frequency measurement of civil infrastructures | |
| JP2001513233A (en) | Method and apparatus for checking the validity of a coin | |
| US2656714A (en) | Method and apparatus for nondestructive investigation of magnetostrictive solids | |
| EP0705422B1 (en) | Continuous monitoring of reinforcements in structures | |
| JP2902532B2 (en) | Vibration body inspection method and device | |
| WO1999053282A1 (en) | Method and apparatus for conducting in-situ nondestructive tensile load measurements in cables and ropes | |
| US4827216A (en) | Differential triple-coil tester for wire rope with periodic lay effect cancellation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |