WO2000055591A1 - Damage indicator - Google Patents

Damage indicator Download PDF

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Publication number
WO2000055591A1
WO2000055591A1 PCT/GB2000/000505 GB0000505W WO0055591A1 WO 2000055591 A1 WO2000055591 A1 WO 2000055591A1 GB 0000505 W GB0000505 W GB 0000505W WO 0055591 A1 WO0055591 A1 WO 0055591A1
Authority
WO
WIPO (PCT)
Prior art keywords
cumulative
damage
tang means
recording
vibration
Prior art date
Application number
PCT/GB2000/000505
Other languages
French (fr)
Inventor
Ronald David Sexton
Original Assignee
Matra Bae Dynamics (Uk) Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Matra Bae Dynamics (Uk) Limited filed Critical Matra Bae Dynamics (Uk) Limited
Priority to AU25584/00A priority Critical patent/AU2558400A/en
Publication of WO2000055591A1 publication Critical patent/WO2000055591A1/en

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0033—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by determining damage, crack or wear
    • 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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0066—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by exciting or detecting vibration or acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M5/00—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings
    • G01M5/0091—Investigating the elasticity of structures, e.g. deflection of bridges or air-craft wings by using electromagnetic excitation or detection
    • G—PHYSICS
    • G07—CHECKING-DEVICES
    • G07C—TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE
    • G07C3/00—Registering or indicating the condition or the working of machines or other apparatus, other than vehicles
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0664—Indicating or recording means; Sensing means using witness specimens

Definitions

  • This invention relates to the field of load monitoring of structures and more particularly, to the measurement of cumulative fatigue damage.
  • the monitoring and recording of cumulative damage is an essential requirement for the assessment of reliability.
  • the current state of the art methods suffer from either a subjective element of mission profile selection for the calculation of a fatigue index, or prohibitive cost, complexity and additional mass in relation to current electronic in service damage monitoring systems.
  • Our invention provides both apparatus and a method of recording cumulative vibration or fatigue damage, which can be utilised across a wide range of structures, with significantly reduced cost and complexity in relation to the current state of the art techniques.
  • apparatus for the recording of cumulative fatigue damage comprising at least one tang means, said tang means being so disposed in relation to a structure such that vibration loading seen by said structure is transmitted to said tang means, said at least one tang means being so designed as to visibly mechanically fail at a predetermined level of cumulative vibration damage.
  • a method of recording levels of cumulative damage applied to a structure whereby at least one tang means is so placed in relation to said structure such that vibration loads seen by said structure are transmitted to said at least one tang means, said at least one tang means being so designed as to visibly mechanically fail at a predetermined level of cumulative damage, thereby providing visible evidence of such predetermined level of cumulative damage being reached by said structure.
  • Figure 1a shows a diagrammatic representation of a cumulative damage indicator in accordance with the invention
  • Figure 1b shows a diagrammatic representation of a cumulative damage indicator wherein a number of the tang means have visibly mechanically failed
  • Figure 2 shows a diagrammatic representation of a cumulative damage indicator attached to a mechanical structure in accordance with the invention
  • Figure 3 shows a diagrammatic representation of a cumulative damage indicator mounted in a visual reference box.
  • a cumulative damage indicator 2 in accordance with the invention is shown in Figure 1 , comprising a plurality of longitudinally extending tang means 4.
  • the tang means 4 are connected to a main body element 6 comprising two positions 8 for attaching the cumulative damage indicator 2 to a chosen piece of structure (not shown).
  • Each of the tang means 4 may be integral with the main body element 6, or may be mechanically or adhesively fastened thereto.
  • Figure 1 b shows a cumulative damage indicator 2 which has been subject to a range of different frequency vibration loads resulting in a number of said tangs visibly mechanically failing 4' .
  • Each of the longitudinally extending tangs 4 can be manufactured to exhibit a natural frequency of vibration required for their particular application. State of the art methods exist whereby each of said tangs 4 can be "tuned” to exhibit a desired natural frequency of vibration, and additionally, each of said tangs can be designed to visibly mechanically fail at a predetermined number of vibration cycles or a range thereof.
  • the mechanism by which tuning of the tangs may be accomplished may include shaping of the tangs by tapering or wasting, adding masses to the tangs at discrete locations, or providing sliding tang elements whereby tang length may be altered. -4. -
  • a cumulative damage indicator 2 in accordance with the invention is shown in Figure 2 attached to a section of aircraft structure 10.
  • the cumulative damage indicator 2 is shown attached to the structure 10 by bolts 12 but equally any other form of mechanical or adhesive attachment that provides a vibration load path from the structure 10 to the cumulative damage indicator 2 will be in accordance with the invention.
  • the location of the cumulative damage indicator 2 in relation to the structure 10 will be determined for each particular structure type, such that the in service vibration loads seen by the cumulative damage indicator 2, will be representative of the loads seen by the overall structure 10 to which it is attached.
  • FIG 3 shows a visual reference box 14 housing a cumulative damage indicator 2 in accordance with the invention.
  • the assembly (14, 2) is attached to a structure under test or observation, such that vibration loads are transmitted in a similar fashion to that described for Figure 2 above.
  • the visual reference box 14 is provided with a viewing window 16 such that the state of the tangs, and additionally should any of said tangs may be observed have visually mechanically failed, they will still remain in the visual reference box 14 thereby reducing the possibility of foreign object damage to the surrounding structure or equipment by the broken tangs.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Aviation & Aerospace Engineering (AREA)
  • Electromagnetism (AREA)
  • Measurement Of Mechanical Vibrations Or Ultrasonic Waves (AREA)
  • Testing Of Devices, Machine Parts, Or Other Structures Thereof (AREA)

Abstract

A load monitoring system for determining levels of cumulative fatigue damage in mechanical structures, comprising mechanical elements which visibly mechanically fail at a predetermined level of cumulative fatigue damage.

Description

DAMAGE INDICATOR
This invention relates to the field of load monitoring of structures and more particularly, to the measurement of cumulative fatigue damage.
Mechanical structures are generally subject to varying in service vibration or "fatigue" load conditions throughout their working life. When attempting to assess the effects of such in service loading on the reliability of structures, there is often a requirement to measure or estimate the cumulative damage seen by the structure. Various empirical methods exist whereby structures such as automobiles and aircraft are assessed for the effects of cumulative vibration or "fatigue" damage by summating the number of in-service hours, multiplied by some "damage" or "fatigue index", thereby resulting in the calculation of a quantitative estimate of the cumulative damage level.
More accurate techniques have been developed to monitor and record cumulative damage, such as the use of electronic in-flight load measurement devices, as used in some military and civil aircraft. The use of electronic techniques requires complicated and expensive recording equipment, which can add both additional mass and cost to the development and running costs of any structure to which they are applied.
The monitoring and recording of cumulative damage is an essential requirement for the assessment of reliability. The current state of the art methods suffer from either a subjective element of mission profile selection for the calculation of a fatigue index, or prohibitive cost, complexity and additional mass in relation to current electronic in service damage monitoring systems. Our invention provides both apparatus and a method of recording cumulative vibration or fatigue damage, which can be utilised across a wide range of structures, with significantly reduced cost and complexity in relation to the current state of the art techniques.
Accordingly there is provided apparatus for the recording of cumulative fatigue damage comprising at least one tang means, said tang means being so disposed in relation to a structure such that vibration loading seen by said structure is transmitted to said tang means, said at least one tang means being so designed as to visibly mechanically fail at a predetermined level of cumulative vibration damage.
Additionally there is provided a method of recording levels of cumulative damage applied to a structure, whereby at least one tang means is so placed in relation to said structure such that vibration loads seen by said structure are transmitted to said at least one tang means, said at least one tang means being so designed as to visibly mechanically fail at a predetermined level of cumulative damage, thereby providing visible evidence of such predetermined level of cumulative damage being reached by said structure.
The invention will now be described by way of example only with reference to the accompanying drawings in which;
Figure 1a shows a diagrammatic representation of a cumulative damage indicator in accordance with the invention,
Figure 1b shows a diagrammatic representation of a cumulative damage indicator wherein a number of the tang means have visibly mechanically failed, Figure 2 shows a diagrammatic representation of a cumulative damage indicator attached to a mechanical structure in accordance with the invention,
Figure 3 shows a diagrammatic representation of a cumulative damage indicator mounted in a visual reference box.
A cumulative damage indicator 2 in accordance with the invention is shown in Figure 1 , comprising a plurality of longitudinally extending tang means 4. The tang means 4 are connected to a main body element 6 comprising two positions 8 for attaching the cumulative damage indicator 2 to a chosen piece of structure (not shown). Each of the tang means 4 may be integral with the main body element 6, or may be mechanically or adhesively fastened thereto.
Figure 1 b shows a cumulative damage indicator 2 which has been subject to a range of different frequency vibration loads resulting in a number of said tangs visibly mechanically failing 4' .
Each of the longitudinally extending tangs 4 can be manufactured to exhibit a natural frequency of vibration required for their particular application. State of the art methods exist whereby each of said tangs 4 can be "tuned" to exhibit a desired natural frequency of vibration, and additionally, each of said tangs can be designed to visibly mechanically fail at a predetermined number of vibration cycles or a range thereof. The mechanism by which tuning of the tangs may be accomplished may include shaping of the tangs by tapering or wasting, adding masses to the tangs at discrete locations, or providing sliding tang elements whereby tang length may be altered. -4. -
A cumulative damage indicator 2 in accordance with the invention is shown in Figure 2 attached to a section of aircraft structure 10. The cumulative damage indicator 2 is shown attached to the structure 10 by bolts 12 but equally any other form of mechanical or adhesive attachment that provides a vibration load path from the structure 10 to the cumulative damage indicator 2 will be in accordance with the invention. The location of the cumulative damage indicator 2 in relation to the structure 10 will be determined for each particular structure type, such that the in service vibration loads seen by the cumulative damage indicator 2, will be representative of the loads seen by the overall structure 10 to which it is attached.
Figure 3 shows a visual reference box 14 housing a cumulative damage indicator 2 in accordance with the invention. The assembly (14, 2) is attached to a structure under test or observation, such that vibration loads are transmitted in a similar fashion to that described for Figure 2 above. The visual reference box 14 is provided with a viewing window 16 such that the state of the tangs, and additionally should any of said tangs may be observed have visually mechanically failed, they will still remain in the visual reference box 14 thereby reducing the possibility of foreign object damage to the surrounding structure or equipment by the broken tangs.
The applications for such a cumulative damage indicator and/or method of recording are numerous, and could extend to their application in relation to domestic appliances such as televisions, radios, washing machines and the like, along with commercial and military uses in relation to missiles, aircraft, ships, automobiles and related equipment.

Claims

1. Apparatus for the recording of cumulative fatigue damage comprising at least one tang means, said tang means being so disposed in relation to a structure such that vibration loads seen by said structure are transmitted to said tang means, said at least one tang means being so designed as to visibly mechanically fail at a predetermined level of cumulative vibration damage.
2. Apparatus for the recording of cumulative fatigue damage in accordance with claim 1 , wherein each of said at least one tang means are connected to a main body element.
3. Apparatus for the recording of cumulative fatigue damage in accordance with claims 1 or 2 above, wherein one or more of said tang means are so designed to have different natural frequencies of vibration.
4. Apparatus for the recording of cumulative fatigue damage in accordance with claims 1 , 2 or 3 above, wherein at least one or said tang means is so designed to visibly mechanically fail at a different predetermined level of cumulative vibration damage.
5. A method of recording the level of cumulative damage applied to a structure whereby at least one tang means is so placed in relation to said structure that vibration loads seen by said structure are transmitted to said at least one tang means, said at least one tang means being so designed as to visibly mechanically fail at a predetermined level of cumulative damage, thereby providing visible evidence of such predetermined level of cumulative damage seen by said structure.
6. Apparatus for the recording of cumulative fatigue damage substantially as hereinbefore described with reference to the accompanying drawings.
7. A method of recording the level of cumulative damage substantially as hereinbefore described with reference to the accompanying drawings.
PCT/GB2000/000505 1999-03-17 2000-02-16 Damage indicator WO2000055591A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU25584/00A AU2558400A (en) 1999-03-17 2000-02-16 Damage indicator

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB9906165.7 1999-03-17
GBGB9906165.7A GB9906165D0 (en) 1999-03-17 1999-03-17 Damage indictor

Publications (1)

Publication Number Publication Date
WO2000055591A1 true WO2000055591A1 (en) 2000-09-21

Family

ID=10849821

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB2000/000505 WO2000055591A1 (en) 1999-03-17 2000-02-16 Damage indicator

Country Status (3)

Country Link
AU (1) AU2558400A (en)
GB (1) GB9906165D0 (en)
WO (1) WO2000055591A1 (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130220210A1 (en) * 2012-02-28 2013-08-29 Meritor Heavy Vehicle Braking Systems (Uk) Limited Cast or forged component with fatigue life indication
WO2019109172A1 (en) 2017-12-04 2019-06-13 Bombardier Inc. Health monitoring of ozone converter
GB2597805A (en) * 2020-08-07 2022-02-09 Mbda Uk Ltd Monitoring system

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3572091A (en) * 1968-09-27 1971-03-23 Keith H Mcfarland Mechanical strain indicator
US4590804A (en) * 1984-01-23 1986-05-27 Tensiodyne Scientific Corporation Device for monitoring fatigue life
DE3703946A1 (en) * 1987-02-09 1988-08-18 Fraunhofer Ges Forschung Frequency-selective vibration sensor
WO1994001738A1 (en) * 1992-07-01 1994-01-20 Tensiodyne Corporation A device for monitoring the fatigue life of a structural member and a method of making same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3572091A (en) * 1968-09-27 1971-03-23 Keith H Mcfarland Mechanical strain indicator
US4590804A (en) * 1984-01-23 1986-05-27 Tensiodyne Scientific Corporation Device for monitoring fatigue life
DE3703946A1 (en) * 1987-02-09 1988-08-18 Fraunhofer Ges Forschung Frequency-selective vibration sensor
WO1994001738A1 (en) * 1992-07-01 1994-01-20 Tensiodyne Corporation A device for monitoring the fatigue life of a structural member and a method of making same

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130220210A1 (en) * 2012-02-28 2013-08-29 Meritor Heavy Vehicle Braking Systems (Uk) Limited Cast or forged component with fatigue life indication
WO2019109172A1 (en) 2017-12-04 2019-06-13 Bombardier Inc. Health monitoring of ozone converter
CN111433582A (en) * 2017-12-04 2020-07-17 庞巴迪公司 Health status monitoring of ozone converter
EP3721201A4 (en) * 2017-12-04 2021-08-18 Bombardier Inc. Health monitoring of ozone converter
CN111433582B (en) * 2017-12-04 2022-08-02 庞巴迪公司 Health status monitoring of ozone converter
GB2597805A (en) * 2020-08-07 2022-02-09 Mbda Uk Ltd Monitoring system
GB2597805B (en) * 2020-08-07 2024-02-28 Mbda Uk Ltd Monitoring system

Also Published As

Publication number Publication date
AU2558400A (en) 2000-10-04
GB9906165D0 (en) 1999-05-12

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