CN103994922B - A kind of stretching based on electromagnetic force and compression stress wave producer and experimental technique - Google Patents
A kind of stretching based on electromagnetic force and compression stress wave producer and experimental technique Download PDFInfo
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- CN103994922B CN103994922B CN201410171963.8A CN201410171963A CN103994922B CN 103994922 B CN103994922 B CN 103994922B CN 201410171963 A CN201410171963 A CN 201410171963A CN 103994922 B CN103994922 B CN 103994922B
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Abstract
A kind of stretching based on electromagnetic force and compression stress wave producer and experimental technique.Described stress wave generator is to connect stating capacitor charger with loading rifle.Main coil, insulating barrier and secondary coil are all sleeved on the locating shaft on tapered amplifier.It is used for the heavy current instantaneous to the main coil offer loading rifle by electric power system, so that producing strong electromagnetic repulsion between main coil and secondary coil, and electromagnetic repulsion force being converted into stress wave, exporting to Hopkinson bar after tapered amplifier amplifies.Present configuration is simple, controllability is strong, it is possible to realizes tradition split hopkinson bar and tests be beyond one's reach strain rate and range of strain, makes the standardization of Hopkinson bar experimental technique, and the experimental provision making pull bar and depression bar realizes integration, save the complexity of equipment and take up an area space.
Description
Technical field
The present invention relates to stress wave generating means and the method for the dynamic mechanical test of material, a kind of base
In stress wave generating means and the method for electromagnetic force, described device can be as separate type Hopkinson pull rod and depression bar
Stress wave input equipment.
Background technology
At present, most popular when measuring material mechanical property under high strain-rate in material science it is exactly
Split hopkinson press bar technology and pull bar technology.The ultimate principle of this method is: short sample is placed in two and draws
Between bar or depression bar, by certain mode to incident bar input tensile stress wave or compression stress wave, sample is carried out
Load.Utilization simultaneously is bonded at the foil gauge on pull bar or depression bar and away from boom end certain distance and carrys out recording pulse signal.As
Really pull bar or depression bar keep elastic stage, then the pulse in bar will be propagated without distortions with elastic wave velocity.So paste
Foil gauge on pull bar or depression bar just can be measured that the load course over time acting on rod end.
For Hopkinson pressure bar, producing the universal way of incidence wave is by trip rod transmitted at high speed by air gun, and enters
Rhizoma Belamcandae Impinging coaxial produces incident pulse.The shortcoming of this method is: during owing to launching every time, trip rod is in air gun
Installation site be not quite similar, and the corresponding relation of stroke speed and air pressure is difficult to determine, therefore cannot control exactly
The amplitude of incidence wave, so needing to attempt many experiments just can obtain required strain rate.Secondly, for strain rate across
Spend big experiment, due to the restriction of air gun air pressure, need the length changing trip rod to obtain different strain rates,
Strain rate is the highest, and trip rod used is the shortest, and the stress wave width produced in experiment is the shortest, which limits experiment gained
The range of strain arrived, and complex operation.The more important thing is, owing to the emission rate of trip rod has a lower limit, one
A little lower strain rates cannot obtain with tradition Hopkinson pressure bar in actual tests, the strain rate of such as 10s-1.By
The most different in different experimental system parameters so that the standardization of split hopkinson press bar experimental technique is always one
An individual international difficult problem.
For Hopkinson pull rod, currently used universal loading technique is: the trip rod of pull bar is made open circles
Pipe, by air gun by impact tube transmitted at high speed, when its motion arrives incident bar end, impact tube is convex with incident rod end
Platform collision produces string compression wave direction incident bar boss end and propagates, and is reflected into tensile wave at free end, and this tensile wave leads to
Cross incident bar sample is loaded.But this method for designing has a lot of shortcomings: 1, owing to trip rod is from entering
Rhizoma Belamcandae one end is transmitted into the other end, so the boss on incident bar is to that section of air gun, incident bar is in without supporting
Free state this incident bar is easily bent；2, the length of this design limit impacting tube at about 500mm,
So a length of about the 0.2ms of incidence wave produced, but ductile material and low strain dynamic rate are tested, need more
Long incidence wave；3, the replacing of impacting tube is very inconvenient；4, owing to the wall thickness of impacting tube limits, need the highest
Air pressure carry out accelerating impact cylinder.Also there is a lot of scholar to propose different mentalities of designing: 1, add one in one end of impacting tube
Individual boss improves the emission rate of impacting tube, but the waveform that this mode produces is affected by boss and the most regular；2,
Using the incident bar of sky, trip rod passes inside incident bar, and this mode makes waveform shaping become difficulty.
Owing to the shape of trip rod is different, the position of air gun is different, the loading system of traditional Hopkinson pressure bar and pull bar
System cannot realize on same device.
The sixties in 20th century, Boeing Co. was to solve the problem that common riveting exists, by Huber A Schmitt
Et al. the Electromagnetic riveting technology that begins one's study that takes the lead in, and applied for the patent of thump electromagnetic riveting device in nineteen sixty-eight.
Within 1986, Zieve Peter succeeds in developing low voltage electromagnetic riveting, solves high pressure and is riveted on riveting quality and popularization and application
The problem that aspect exists, so that Electromagnetic riveting technology is comparatively fast developed.Electromagnetic riveting technology is at Boeing, Air Passenger
Series aircraft manufacture is applied.Nowadays, low voltage electromagnetic riveting technology has developed into ripe, the size of rivet force and
Persistent period can obtain more accurate control.The know-why of electromagnetic rivet driver is: between discharge coil and workpiece
Add a coil and Stress-amplifier.The moment of discharge switch Guan Bi, by fast-changing punching in main coil
Hit electric current, around coil, produce high-intensity magnetic field.The secondary coil coupled with main coil produces faradism under strong magnetic field action
Stream, and then produce eddy current magnetism, two magnetic field interactions produce eddy current repulsion, and reach rivet by amplifier, make
Rivet shapes.The very high frequency of eddy current power, in amplifier and rivet, the form with stress wave is propagated, therefore electromagnetic riveting
Also referred to as stress wave riveting.If being applied to the principle of electromagnetic rivet driver in split hopkinson press bar replace tradition to separate
Air gun in formula Hopkinson pressure bar and trip rod, produced by electromagnetic repulsion force and directly produce stress wave, it will make separation
The standardization of formula Hopkinson pressure bar experiment technology is possibly realized.And with sufficiently long stress pulse, sample can be entered
Row low strain dynamic rate loads, it is achieved the low strain dynamic rate that some tradition Hopkinson bars cannot realize.Northwestern Polytechnical University is in Shen
Please number for 201410161610.X innovation and creation in propose a kind of based on electromagnetic force load separate type Hopkinson
Strut device, this device is by directly applying to Hopkinson pressure bar experiment device by electromagnetic rivet driver device, thus realizes
The dynamic compression of sample is loaded.But reality is more desirable to use same charger, both can produce pressure
Stress under compression ripple, can produce again tensile stress wave.
Summary of the invention
For overcoming incidence wave amplitude present in prior art to be difficult to control to, complex operation and range of strain limit and
The deficiency of some low strain dynamic rates experiment, and the shortcoming that stretching and compression-loaded device cannot be unified cannot be realized, this
Bright propose a kind of stretching based on electromagnetic force and compression stress wave producer and experimental technique.
Described stretching based on electromagnetic force and compression stress wave producer include power supply, capacitor charger and loading rifle.Institute
State capacitor charger and use the power pack of existing electromagnetic rivetter, and the positive pole of the output by described capacitor charger
Output lead connects with the electrode line loading rifle, and negative pole output lead connects with the negative line loading rifle.Load rifle and include taper
Amplifier, insulating barrier, loading gun housing body, main coil and secondary coil.Tapered amplifier is positioned at described loading gun housing body
And it is arranged on this loading rifle shell one end；Locating shaft on this tapered amplifier also be positioned at loading gun housing body and with loading
Gun housing body is coaxial.Main coil, insulating barrier and secondary coil are all sleeved on the locating shaft on described tapered amplifier.Absolutely
The inner surface laminating of edge layer and described tapered amplifier；Secondary coil is positioned at inside described insulating barrier；Same loading gun housing body
The circumferential surface of side has the via of two external connectors of main coil.The external peripheral surface of tapered amplifier and loading rifle
The internal surface gaps of housing coordinates.
The circumferential surface of tapered amplifier one end is made up of isometrical section and cone section；The axial length of described isometrical section: cone section
Axial length=1:1.Isometrical section of described tapered amplifier is stress wave receiver section, the cone of described tapered amplifier
Section amplifies reflection end for stress wave.The diameter of stress wave receiver section is maximum, and at the end face center of stress wave receiver section
There is axially projecting locating shaft；Stress wave amplifies the center of reflection end axially projecting cooperation section, defines in this place
The minimum diameter of stretching head, and the female thread of incident bar for connecting Hopkinson pressure bar it is machined with in described cooperation section.
The diameter of the stress wave receiving terminal of described tapered amplifier: ratio=12 at the minimum diameter of stress wave amplification reflection end:
1.The tapering of the cone section that described stress wave amplifies reflection end is 30.
The present invention also proposes the experimental technique of a kind of Hopkinson strut and tie stress wave generator based on electromagnetic force, including
Hopkinson compression experiment and Hopkinson stretching experiment.Described Hopkinson strut and tie stress wave based on electromagnetic force is sent out
The experimentation of raw device is:
Step 1. is arranged equipment.
Loading rifle, incident bar and transmission bar coaxial order according to a conventional method is arranged in laboratory table, and makes described incidence
Bar and transmission bar only can move freely at axis direction.One sample is arranged between incident bar and transmission bar, and
And make sample coaxial with incident bar and transmission bar.
Step 2. pastes foil gauge.
Use conventional method to paste 2 foil gauges respectively at incident bar or transmission bar, and foil gauge lead-in wire is accessed data
Acquisition system；During described foil gauge of arranging lead-in wire, must be by described each foil gauge lead-in wire and incident bar or the axis of transmission bar
Parallel distribution, then it is perpendicular to axis direction bending at a right angle extraction, make foil gauge lead-in wire linear state access data acquisition
Storage.
Step 3. loading experiment and data acquisition.
When carrying out Hopkinson compression experiment, tapered amplifier is installed in loading rifle, makes described tapered amplifier
Small end towards the incident bar of Hopkinson pressure bar, the incident bar of the small end of tapered amplifier with Hopkinson pressure bar is entered
Row is threaded, and makes secondary coil fit together with an end face of main coil.Electric capacity is made to fill by electrical switch
The main coil loading rifle is discharged by electrical equipment, will produce electromagnetic repulsion force, described electromagnetism between tapered amplifier and main coil
Repulsion forms incidence wave, this incidence after showing as compression stress wave inside tapered amplifier and being amplified by tapered amplifier
The incident bar of the incoming Hopkinson pressure bar of ripple, when this incidence wave reaches incident bar with sample contacts face, due to natural impedance
Not mating, a part for this incidence wave is reflected, and forms echo in incident bar, and another part is then saturating by sample
Inject in transmission bar, form transmitted wave.Described echo and the shape of transmitted wave and amplitude are to be determined by sample material character
Fixed.Incidence wave and reflection wave signal are recorded by data acquisition unit by the foil gauge being pasted onto on incident bar, logical
Cross the foil gauge being pasted onto on transmission bar to be got off by the signal record of transmitted wave.Utilize the echo of data acquisition unit record
With transmitted wave signal, obtained the dynamic compressing stress strain curve of test specimen by a ripple method.
When carrying out Hopkinson stretching experiment, tapered amplifier is installed in loading rifle, makes described tapered amplifier
Small end be directed away from the direction of incident bar of Hopkinson pressure bar, being drawn with Hopkinson by the locating shaft of tapered amplifier
The incident bar of bar carries out threaded, and makes secondary coil fit together with an end face of main coil.Pass through electronics
Switch makes capacitor charger discharge the main coil loading rifle, will produce electromagnetism and scold between tapered amplifier and main coil
Power, described electromagnetic repulsion force shows as compression stress wave inside tapered amplifier, and described compression stress wave is amplified in taper
It is exaggerated in device, and is reflected into tensile wave at the small end of tapered amplifier and forms the incidence wave of Hopkinson pull rod, should
The incident bar of the incoming Hopkinson pull rod of incidence wave, when this incidence wave reaches incident bar with sample contacts face, due to ripple
Impedance mismatch, a part for this incidence wave is reflected, and forms echo in incident bar, and another part is then by examination
Sample transmission enters in transmission bar, forms transmitted wave.Described echo and the shape of transmitted wave and amplitude are by sample material
Matter determines.Incidence wave and reflection wave signal are recorded by data acquisition unit by the foil gauge being pasted onto on incident bar,
By the foil gauge being pasted onto on transmission bar, the signal record of transmitted wave is got off.Utilize the reflection of data acquisition unit record
Ripple and transmitted wave signal, obtain the dynamic compressing stress strain curve of test specimen by a ripple method.
In the present invention, stress wave generating means is by loading rifle and electric power system forms.Electric power system is used for loading rifle
Main coil provide instantaneous heavy current, so that producing strong electromagnetic repulsion between main coil and secondary coil.Load rifle by
Main coil, secondary coil and tapered amplifier composition, be used for producing electromagnetic repulsion force, and electromagnetic repulsion force be converted into stress wave,
Export to Hopkinson bar after tapered amplifier amplifies.
The present invention makes it can produce compression stress wave by improving the structure of electromagnetic rivet driver, can produce again tensile stress
Ripple, and it is applied to the loading of split hopkinson press bar and pull bar, make the loading system of Hopkinson pressure bar and pull bar
System can realize on same device simultaneously.The present invention has a main coil and a secondary coil in loading rifle, main
Coil is fixed with gun body, is positioned at the interlude of gun body, and there is through hole at main coil center, is used for positioning with tapered amplifier；
Secondary coil is copper disk, and be connected a tapered amplifier, and described tapered amplifier is close with main coil.Main coil and
Tapered amplifier is coaxial, and its axiality is coordinated with the through hole of main coil by the locating shaft of tapered amplifier and determines.Do
During compression experiment, by the small end of tapered amplifier near Hopkinson pressure bar incident bar install, and coordinate section with suddenly
The incident bar of Pu Jinsen depression bar is attached by screw thread；When doing stretching experiment, by the small end of tapered amplifier away from suddenly
The incident bar of Pu Jinsen pull bar, passes the through hole of main coil by the locating shaft of this tapered amplifier, and at the one of locating shaft
The incident bar with Hopkinson pull rod is held to be attached by screw thread.During experiment, by strong variable-current by main coil,
Main coil can produce the high-intensity magnetic field of change, and the high-intensity magnetic field of change can produce faradic current in secondary coil, and faradism is miscarried
Raw induced field direction is contrary with the magnetic direction of main coil, then produces electromagnetic repulsion force between main coil and secondary circle,
This electromagnetic repulsion force shows as compression stress wave in secondary coil, and this compression stress wave is amplified by tapered amplifier,
In Hopkinson compression experiment, the compression stress wave of this amplification enters as the direct incoming Hopkinson pressure bar of incidence wave
Rhizoma Belamcandae, it is possible to material is compressed test；When Hopkinson stretching experiment, the compressional wave of this amplification is in taper
Become the tensile wave of constant amplitude after the small end reflection of amplifier, and change the direction of propagation, by the locating shaft of tapered amplifier
The incident bar of incoming Hopkinson pull rod, it is possible to material is carried out dynamic tensile loading.Therefore this device both can be right
Material is compressed experiment, can carry out again stretching experiment.
Serving as theme to enclose by the electric discharge of capacitor and provide power supply, owing to capacitor discharge time is comparatively short, discharge current is strong,
Can make to produce between main coil and secondary coil the strong repulsion of moment, thus produce strong stress pulse.As for capacitor
Charging and discharging control system, in electromagnetic rivetter, this technology is the most highly developed at present, can directly apply.
Tapered amplifier is threaded connection with the incident bar of Hopkinson bar, enables the stress wave of output stably to pass
Enter experimental system.In the experimental provision of the present invention, by loading the electromagnetic repulsion force between main coil and the secondary coil in rifle
Directly produce stress pulse, be input to incident bar so that produced pulse signal can be according to the needs of experimenter
Relatively accurately it is controlled.
In the present invention, the actual stress wave amplitude produced can be controlled by the charging voltage of electromagnetic riveting device, real
The stress wave width that border produces can be controlled by adjusting the capacitance of electromagnetic riveting device.
Electromagnetic repulsion force is combined in principle by the present invention with capacitor discharge, to replace tradition split hopkinson bar
Air gun and bullet in system and directly produce stress pulse.Use traditional Hopkinson bar sample, can be to material
Carry out the loading under expection pulse amplitude and pulse width.Equipment whole system is simple to operate, and controllability is strong.Owing to being
It is controlled by electromagnetic mode correspondence Reeb, when the capacitance in capacitor charger is constant, same voltage pair
The output stress wave amplitude answered is the most constant, and when charging voltage is constant, stress wave width corresponding to same capacitance is also
Constant, it is possible to realize the accurate control of corresponding Reeb, experiment reproducible；Secondly as be to pass through electromagnetism
Loading the stress wave produced, the width of stress pulse clashes into the restriction of the pole length that is impacted mode, institute unlike tradition
To test for low strain dynamic rate, the strain ratio tradition Hopkinson bar that the present invention can reach is bigger, such as, and the present invention
The stress wave that pulse width is 0.5ms can be produced, if sample is carried out under 100s-1 strain rate with this stress wave
Compression test, then the maximum strain that sample can reach is 0.05, and for tradition Hopkinson bar, is extremely difficult to this
Low strain rate, even if this strain rate can be reached, bullet used is 0.8m, then the stress pulse width produced
For 0.32ms, then the maximum strain that sample reaches is 0.032, hence it is evident that the Hopkinson bar loaded less than electromagnetism.Due to
Above advantage, apparatus of the present invention and method can realize tradition split hopkinson bar and test the strain rate that is beyond one's reach
And range of strain, make the standardization of Hopkinson bar experimental technique, and make the experimental provision of pull bar and depression bar realize one
Body, saves the complexity of equipment and takes up an area space.
Accompanying drawing explanation
Fig. 1 is stretching based on electromagnetic force and the schematic diagram of compression stress wave producer；
Fig. 2 is stretching based on electromagnetic force and the structural representation of compression stress wave producer；
Fig. 3 is the internal structure schematic diagram loading rifle, and its middle shell is cut open along symmetrical plane.
Fig. 4 is the structural representation of tapered amplifier；
Fig. 5 is compression test schematic diagram；
Fig. 6 is tension test schematic diagram；
Fig. 7 is the location mode of foil gauge lead-in wire；
Fig. 8 is the stress signal that general foil gauge lead mode for cloth measures, and wherein abscissa express time, unit is
S, vertical coordinate represents that stress, unit are Mpa；
Fig. 9 is the stress signal using the foil gauge lead mode for cloth in the present invention to measure, when wherein abscissa represents
Between, unit is s, and vertical coordinate represents that stress, unit are Mpa.
In figure:
1. resistance；2. transformator；3. commutator；4. electric capacity；5. electrical switch；6. load rifle；7. tapered amplifier；8.
Insulating barrier；9. secondary coil；10. housing；11. main coils；12. incident bars；13. samples；14. transmission bars；15. foil gauges；
16. data acquisition units；17. buffers；18. capacitor chargers；19. power supplys；20. screw threads；21. locating shafts；22. lead-in wires.
Detailed description of the invention
The present embodiment is a kind of stretching based on electromagnetic force and compression stress wave producer, including power supply 19, electric capacity charging
Device 18 and loading rifle 6.Capacitor charger 18 uses the power pack of existing electromagnetic rivetter, and by described electric capacity
The positive pole output lead of the output of charger 18 connects with the electrode line loading rifle 6, and negative pole output lead is negative with loading rifle 6
Polar curve connects.Power supply 19 uses the three-phase alternating current of 220V.
In the present embodiment, capacitor charger 18 uses the electromagnetism in the patent being published in Patent No. 200520079179
The power pack of riveting equipment, in this example, by 10 rated voltages be 1000 volts of rated capacities be 2000 microfarads
Electrochemical capacitor composes in parallel Capacitor banks, is arranged in capacitor box, described Capacitor banks and electrical switch by electricity
The electric discharge of sub-on-off control Capacitor banks.Control chamber mainly comprises PLC and control system thereof.Control system is mainly by mould
Intend controlling part, digital control part and digital display portion composition.Wherein simulation control part uses SIEMENS
The TCA785 chip of company.Digital control part is inputted by S7-200 series CPU224 and Siemens's simulation of Siemens
Output expansion module EM235 composition.Charging voltage controls mainly by Voltage loop and the pid control mode of electric current loop
Realize.Digital display portion mainly consists of S7-200 series text display TD200.
As shown in Figure 3.Load rifle to be made up of tapered amplifier 7, secondary coil 9, housing 10 and main coil 11.Described
Loading gun housing body 10 is carrier, and tapered amplifier 7 is positioned at described loading gun housing body and is arranged on this loading gun housing body one
End；Locating shaft on this tapered amplifier also be positioned at loading gun housing body and with loading gun housing body coaxial, be both used for stretching
The transmission of stress wave, again for the location of main coil 11 secondary coil 9.
Main coil 11 is sleeved on the locating shaft on described tapered amplifier and is positioned at loading gun housing body stage casing.1 Buddhist nun
The insulating barrier 8 that dragon is made is sleeved on the locating shaft on described tapered amplifier, and with described tapered amplifier inner surface
Laminating, stops the incoming tapered amplifier of inductive loop 7 produced in secondary coil 9 by described insulating barrier 8.Secondary coil 9
It is sleeved on the locating shaft on described tapered amplifier, and is positioned at inside described each insulating barrier.Loading gun housing body 10
The circumferential surface of the same side has two through holes, and two external connectors of main coil 11 are each passed through one of them through hole and consolidate
It is scheduled on the outer surface loading gun housing body 10.Positive terminal in two external connectors of described main coil and capacitor charger
The positive pole output lead of 20 connects, and the anode connector in two external connectors connects with the negative pole output lead of capacitor charger 18
Connect.
In the present embodiment, loading gun housing body 10 uses the nylon manufacture that insulating properties are good.The main coil of this loading rifle
It is on I-shaped core body that the 11 wide 25mm of employing, the copper strips of thick 1mm are wound on cross section.The external diameter of main coil 11 with
The internal diameter loading gun housing body 10 is identical, after this main coil loads and loads in gun housing body 10, and interference engagement between the two.
Secondary coil 9 is copper disk, and has axis hole at the center of this secondary coil.
Tapered amplifier 7 is revolving body.One end of tapered amplifier 7 is circular block, and this circular block circumferential surface
It is made up of isometrical section and cone section；The axial length of described isometrical section: axial length=1:1 that cone section is.The present embodiment
In, the axial length of the axial length of isometrical section of described tapered amplifier and cone section is 25mm.Described taper is amplified
Isometrical section of device is stress wave receiver section, and the cone section of described tapered amplifier is that stress wave amplifies reflection end.Stress wave connects
The diameter receiving section is maximum, and has axially projecting locating shaft at the end face center of stress wave receiver section；Stress wave amplifies
Reflection end center has axially projecting cooperation section, described cooperation section to be machined with blind screw hole, be used for connecting Hopkinson
The incident bar of depression bar.The diameter of described tapered amplifier stress wave receiving terminal: stress wave amplifies the minimum diameter of reflection end
Ratio=the 12:1 at place.The tapering of the cone section that described stress wave amplifies reflection end is 30；
The locating shaft 21 of described tapered amplifier is matched in clearance with the through hole of main coil 11.Circle in this locating shaft end
Perimeter surface is machined with blind screw hole, for coordinating with the incident bar of Hopkinson pull rod.
Power supply 19, incident bar 12, transmission bar 14, foil gauge 15, data acquisition unit 16 and buffering in the present embodiment
Device 17 all uses prior art.And it is machined with external screw thread in one end of incident bar 12.
The present embodiment also proposed the experiment side of a kind of described Hopkinson strut and tie stress wave generator based on electromagnetic force
Method.The experimental technique of described stretching based on electromagnetic force and compression stress wave producer includes Hopkinson compression experiment
With Hopkinson stretching experiment.
I uses stretching based on electromagnetic force and compression stress wave producer to carry out the concrete mistake of Hopkinson compression experiment
Cheng Shi:
Step 1. is arranged equipment.
Loading rifle 6, incident bar 12 and transmission bar 14 coaxial order according to a conventional method is arranged in laboratory table, and makes
Described incident bar 12 and transmission bar 14 only can move freely at axis direction.One sample 13 is arranged on incident bar
Between 12 and transmission bar 14, and make sample 13 coaxial with incident bar 12 and transmission bar 14.
Step 2. pastes foil gauge.
The method of attaching of foil gauge uses prior art, i.e. circle at the half length of incident bar 12 or transmission bar 14
With described incident bar or transmission bar axis as axis of symmetry on Zhou, identical for two panels parameter foil gauge symmetry is pasted onto
Incident bar or transmission bar surface, weld strain sheet lead-in wire 22 on the pin of foil gauge, and described foil gauge lead-in wire is connect
Enter in the Wheatstone bridge in data collecting system.
Described foil gauge lead-in wire 22 be placed with particular/special requirement, data acquisition unit 16 otherwise can be made by electromagnetic interference
Cannot normal acquisition experimental data.If foil gauge lead-in wire 22 throwings in the plane being perpendicular to incident bar or transmission bar axis
Shadow formation closed-loop path, then, when loading rifle 6 electric discharge generation high-intensity magnetic field, the magnetic field line of change can be through foil gauge lead-in wire 22
The loop formed, makes to produce in loop the magnetic flux of change, thus forms faradic current, to data acquisition unit 16
Produce interference, make gathered data to use.Solution to this problem is: as it is shown in fig. 7, first make institute
State lead-in wire 22 distributions parallel with the axis of incident bar or transmission bar of each foil gauge, then be perpendicular to axis direction bending at a right angle
Draw, make lead-in wire 22 linear state access data acquisition unit 16, so would not be because of magnetic flux change in lead-in wire
And produce faradic current.From Fig. 8 and Fig. 9 it can be seen that the general stress measured by foil gauge lead mode for cloth
Ripple signal disturbing is very big, and uses the stress wave signal measured by foil gauge lead mode for cloth proposed by the invention
Interference is completely eliminated.
Step 3. carries out loading and processing data.
As it is shown in figure 5, tapered amplifier 7 is installed in loading rifle 6, make the small end of described tapered amplifier towards
The incident bar 12 of Hopkinson pressure bar, carries out screw thread by the incident bar of the small end of tapered amplifier 7 Yu Hopkinson pressure bar
Connect, and make secondary coil 9 fit together with an end face of main coil 11.Charging by capacitor charger 18
Voltage is set to 200V and charges, to be charged complete after, by electrical switch make capacitor charger to load rifle main coil
11 electric discharges, will produce electromagnetic repulsion force between tapered amplifier 7 and main coil 11, described electromagnetic repulsion force is put in taper
Big device 7 inside forms incidence wave after showing as compression stress wave and being amplified by tapered amplifier 7, and this incidence wave is incoming suddenly
The incident bar 12 of Pu Jinsen depression bar, when this incidence wave reaches incident bar 12 with sample 13 contact surface, due to natural impedance
Not mating, a part for this incidence wave is reflected, and forms echo in incident bar 12, and another part then passes through sample
13 transmissions enter in transmission bar 14, form transmitted wave.Described echo and the shape of transmitted wave and amplitude are by sample material
Material character determines.
Incidence wave and reflection wave signal are recorded by data acquisition unit 16 by the foil gauge 15 being pasted onto on incident bar 12
Come, by the foil gauge 15 being pasted onto on transmission bar 14, the signal record of transmitted wave is got off.Utilize data acquisition unit
The echo of 16 records and transmitted wave signal, obtain the dynamic compressing stress strain curve of test specimen by a ripple method.
II uses stretching based on electromagnetic force and compression stress wave producer to carry out the concrete mistake of Hopkinson stretching experiment
Cheng Shi:
Step 1. is arranged equipment.
Loading rifle 6, incident bar 12, the coaxial order of transmission bar 14 are arranged in laboratory table, make described incident bar 12,
Transmission bar 14 only can move freely at axis direction.One sample 13 is arranged on incident bar 12 and transmission bar 14
Between, and make sample 13 coaxial with incident bar 12 and transmission bar 14.
Step 2. pastes foil gauge.
The method of attaching of foil gauge uses prior art, i.e. circle at the half length of incident bar 12 or transmission bar 14
With described incident bar or transmission bar axis as axis of symmetry on Zhou, identical for two panels parameter foil gauge symmetry is pasted onto
Incident bar or transmission bar surface, weld strain sheet lead-in wire 22 on the pin of foil gauge, and described foil gauge lead-in wire is connect
Enter in the Wheatstone bridge in data collecting system.
Described foil gauge lead-in wire 22 be placed with particular/special requirement, data acquisition unit 16 otherwise can be made by electromagnetic interference
Cannot normal acquisition experimental data.If foil gauge lead-in wire 22 throwings in the plane being perpendicular to incident bar or transmission bar axis
Shadow formation closed-loop path, then, when loading rifle 6 electric discharge generation high-intensity magnetic field, the magnetic field line of change can be through foil gauge lead-in wire 22
The loop formed, makes to produce in loop the magnetic flux of change, thus forms faradic current, to data acquisition unit 16
Produce interference, make gathered data to use.Solution to this problem is: as it is shown in fig. 7, first make institute
State lead-in wire 22 distributions parallel with the axis of incident bar or transmission bar of each foil gauge, then be perpendicular to axis direction bending at a right angle
Draw, make lead-in wire 22 linear state access data acquisition unit 16, so would not be because of magnetic flux change in lead-in wire
And produce faradic current.From Fig. 8 and Fig. 9 it can be seen that the general stress measured by foil gauge lead mode for cloth
Ripple signal disturbing is very big, and uses the stress wave signal measured by foil gauge lead mode for cloth proposed by the invention
Interference is completely eliminated.
Step 3. carries out loading and gathering data.
As shown in Figure 6, tapered amplifier 7 is installed in loading rifle 6, make the small end of described tapered amplifier towards
Away from the direction of the incident bar 12 of Hopkinson pressure bar, by locating shaft 20 and the Hopkinson pull rod of tapered amplifier 7
Incident bar carry out threaded, and make secondary coil 9 fit together with an end face of main coil 11.By electric capacity
The charging voltage of charger 18 is set to 200V and charges, to be charged complete after, make capacitor charger by electrical switch
The main coil 11 loading rifle is discharged, electromagnetic repulsion force between tapered amplifier 7 and main coil 11, will be produced, described
Electromagnetic repulsion force shows as compression stress wave inside tapered amplifier 7, and described compression stress wave is in tapered amplifier 7
Being exaggerated, and be reflected into tensile wave at the small end of tapered amplifier 7 and form the incidence wave of Hopkinson pull rod, this enters
The incident bar 12 of the incoming Hopkinson pull rod of ejected wave, when this incidence wave reaches incident bar 12 with sample 13 contact surface,
Owing to natural impedance is not mated, a part for this incidence wave is reflected, and forms echo, another part in incident bar 12
Then enter in transmission bar 14 by sample 13 transmission, form transmitted wave.Described echo and the shape of transmitted wave and amplitude
Determined by sample material character.
Incidence wave and reflection wave signal are recorded by data acquisition unit 16 by the foil gauge 15 being pasted onto on incident bar 12
Come, by the foil gauge 10 being pasted onto on transmission bar 14, the signal record of transmitted wave is got off.Utilize data acquisition unit
The echo of 16 records and transmitted wave signal, obtain the dynamic tensile stress-strain diagram of material by a ripple method.
Claims (4)
1. a stretching based on electromagnetic force and compression stress wave producer, it is characterised in that include power supply, capacitor charger
With loading rifle；Load rifle to be made up of tapered amplifier, secondary coil, housing and main coil, described tapered amplifier position
In described loading gun housing body and be arranged on this loading rifle shell one end；Locating shaft on this tapered amplifier is used for leading
Coil and the location of secondary coil, and for the transmission of tensile stress wave；
Main coil is sleeved on the locating shaft on described tapered amplifier and is positioned at loading gun housing body stage casing；Nylon is made
Insulating barrier is sleeved on the locating shaft on described tapered amplifier, and fits with described tapered amplifier outer surface, logical
Cross described insulating barrier and stop the incoming tapered amplifier of inductive loop produced in secondary coil；Secondary coil is sleeved on described cone
On locating shaft on shape amplifier, and it is positioned at inside this insulating barrier；Have at the circumferential surface loading gun housing body the same side
Two through holes, two external connectors of main coil are each passed through one of them through hole and are fixed on outside loading gun housing body
Surface；Positive terminal in two external connectors of described main coil is connected with the positive pole output lead of capacitor charger,
Anode connector in two external connectors is connected with the negative pole output lead of capacitor charger；
Tapered amplifier is revolving body；The circumferential surface of this tapered amplifier one end is made up of isometrical section and cone section, isometrical section
For stress wave receiver section, cone section is that stress wave amplifies reflection end, and the diameter of stress wave receiver section is maximum, and stress wave connects
There is axially projecting locating shaft at the end face center receiving section；The axial length of described stress wave receiver section: stress wave amplifies
Axial length=the 1:1 of reflection end；
The diameter of described tapered amplifier stress wave receiving terminal: the ratio at the minimum diameter of stress wave amplification reflection end=
12:1；The tapering of the cone section that described stress wave amplifies reflection end is 30.
2. stretching based on electromagnetic force as claimed in claim 1 and compression stress wave producer, it is characterised in that answer described
Reflection end center is amplified in Reeb has axially projecting cooperation section, described cooperation section to be machined with blind screw hole, for even
Connect the incident bar of Hopkinson pressure bar.
3. stretching based on electromagnetic force as claimed in claim 1 and compression stress wave producer, it is characterised in that described taper
The locating shaft of amplifier and the through hole of main coil are matched in clearance；Circumferential surface in this locating shaft end is machined with
Blind screw hole, for coordinating with the incident bar of Hopkinson pull rod.
4. utilize stretching based on electromagnetic force described in claim 1 and a method for compression stress wave producer experiment, described
The experimental technique of stretching based on electromagnetic force and compression stress wave producer includes Hopkinson compression experiment and suddenly
Pu Jinsen stretching experiment；It is characterized in that:
Step 1. is arranged equipment；
Loading rifle, incident bar and transmission bar coaxial order according to a conventional method is arranged in laboratory table, and makes described incident bar
Only can move freely at axis direction with transmission bar；One sample is arranged between incident bar and transmission bar, and
And make sample coaxial with incident bar and transmission bar；
Step 2. pastes foil gauge；
The method of attaching of foil gauge uses prior art, identical for two panels parameter foil gauge symmetry is pasted onto described in enter
Circumferential surface in the middle part of Rhizoma Belamcandae or transmission bar, and described each foil gauge lead-in wire is accessed the favour stone in data collecting system
In electric bridge；When being accessed in data collecting system by each foil gauge lead-in wire, make described each foil gauge lead-in wire and incident bar
Or the parallel distribution of axis of transmission bar, then it is perpendicular to axis direction bending at a right angle extraction, make lead-in wire linear state
Access data acquisition unit；
Step 3. carries out loading and processing data；
I when carrying out Hopkinson compression in real time:
Tapered amplifier is installed in loading rifle, makes the small end incidence towards Hopkinson pressure bar of described tapered amplifier
Bar, threadeds the small end of tapered amplifier with the incident bar of Hopkinson pressure bar, and make secondary coil with
One end face of main coil fits together；Make capacitor charger that the main coil loading rifle to be put by electrical switch
Electricity, will produce electromagnetic repulsion force between tapered amplifier and main coil, described electromagnetic repulsion force is inside tapered amplifier
Compression stress wave and form incidence wave, entering of the incoming Hopkinson pressure bar of this incidence wave after being amplified by tapered amplifier
Rhizoma Belamcandae, when this incidence wave reaches incident bar with sample contacts face, owing to natural impedance is not mated, the one of this incidence wave
Part is reflected, and forms echo in incident bar, and another part then enters in transmission bar by sample transmission, is formed
Transmitted wave；Described echo and the shape of transmitted wave and amplitude are determined by sample material character.
Incidence wave and reflection wave signal are recorded by the foil gauge being pasted onto on incident bar by data acquisition unit, logical
Cross the foil gauge being pasted onto on transmission bar to be got off by the signal record of transmitted wave；Utilize the reflection of data acquisition unit record
Ripple and transmitted wave signal, obtain the dynamic compressing stress strain curve of test specimen by a ripple method；
II when carrying out Hopkinson stretching experiment:
Tapered amplifier is installed in loading rifle, makes the small end of described tapered amplifier be directed away from Hopkinson pressure bar
The direction of incident bar, threadeds the locating shaft of tapered amplifier with the incident bar of Hopkinson pull rod, and
And make secondary coil fit together with an end face of main coil；Make capacitor charger to loading rifle by electrical switch
Main coil electric discharge, electromagnetic repulsion force will be produced between tapered amplifier and main coil, described electromagnetic repulsion force is in taper
Showing as compression stress wave inside amplifier, described compression stress wave is exaggerated in tapered amplifier, and in taper
The small end of amplifier is reflected into tensile wave and forms the incidence wave of Hopkinson pull rod, the incoming Hopkinson of this incidence wave
The incident bar of pull bar, when this incidence wave reaches incident bar with sample contacts face, owing to natural impedance is not mated, this enters
A part for ejected wave is reflected, and forms echo in incident bar, and another part then enters transmission bar by sample transmission
In, form transmitted wave；Described echo and the shape of transmitted wave and amplitude are determined by sample material character；
Incidence wave and reflection wave signal are recorded by the foil gauge being pasted onto on incident bar by data acquisition unit, logical
Cross the foil gauge being pasted onto on transmission bar to be got off by the signal record of transmitted wave；Utilize the reflection of data acquisition unit record
Ripple and transmitted wave signal, obtain the dynamic tensile stress-strain diagram of material by a ripple method.
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