CN108519296A - A kind of dynamic mechanics parameter of material acquisition device and method - Google Patents

A kind of dynamic mechanics parameter of material acquisition device and method Download PDF

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CN108519296A
CN108519296A CN201810255650.9A CN201810255650A CN108519296A CN 108519296 A CN108519296 A CN 108519296A CN 201810255650 A CN201810255650 A CN 201810255650A CN 108519296 A CN108519296 A CN 108519296A
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wave
sample
strain
compression
constrictor
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李玉龙
刘琛琳
金康华
聂海亮
索涛
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Northwestern Polytechnical University
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/26—Investigating twisting or coiling properties
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/32—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces
    • G01N3/38—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by electromagnetic means
    • 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
    • G01N2203/0001—Type of application of the stress
    • G01N2203/0005—Repeated or cyclic
    • 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
    • G01N2203/0014—Type of force applied
    • G01N2203/0016—Tensile or compressive
    • G01N2203/0019—Compressive
    • 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
    • G01N2203/0014—Type of force applied
    • G01N2203/0021—Torsional
    • 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
    • G01N2203/003—Generation of the force
    • G01N2203/005—Electromagnetic means
    • 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
    • G01N2203/0202—Control of the test
    • G01N2203/0208—Specific programs of loading, e.g. incremental loading or pre-loading
    • 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
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0682—Spatial dimension, e.g. length, area, angle

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  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
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  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Electromagnetism (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

The embodiment provides a kind of dynamic mechanics parameter of material acquisition device and method, it can solve the problems, such as that prior art stress wave control precision is low.Described device includes：Electromagnetic type Hopkinson pressure bar loading unit；Electromagnetic type split-Hopkinson torsional bar loading unit；Stress wave synchronization unit；Acquiring unit.The method includes the steps：Load compression stress wave；Load distorting stress wave；Obtain the compression stress parameter of sample；Obtain the distorting stress parameter of sample；Wherein, the compression stress parameter of sample and the distorting stress parameter of sample are as dynamic mechanics parameter of material.The embodiment of the present invention is compressed by the way that the distorting stress wave generating device of electromagnetic drive and compression stress wave generating device are applied to Hopkinson in twisted coupling experiment so that the distorting stress wave and compression stress wave that experimental provision generates are attained by terms of generation time, pulsewidth and amplitude and accurately control.

Description

A kind of dynamic mechanics parameter of material acquisition device and method
Technical field
The present invention relates to dynamic mechanics parameter of material acquisition device and method, specifically a kind of compression based on electromagnetic force Stress wave-distorting stress wave coupling generating unit and method, the unit can be used as separate type Hopkinson compression-torsion multiple Close the experimental considerations unit of load.
Background technology
In practical applications, engineering material suffers from various forms of load with structure and acts on.Wherein many load Action time is all in millisecond, microsecond even nanosecond order；Material is showed when by very short load of this action time Mechanical property with it is quasi-static under the conditions of material mechanical performance it is different.And material is when by this shock loading, from The stress state of body is sufficiently complex, and the load born also has significant changes with time history.Therefore, research height is answered Test method when material bears multiaxis Combined Loading under variability has very high scientific research, application value.
Most popular experiment when being mechanical property of the measurement material under high strain-rate of Hopkinson bar experimental considerations unit One of technology.The basic principle of this method is exactly：Between one short sample is placed in two elongate rods, pass through the quality of acceleration Block, quarter butt are hit or explosive charge generates stress wave, to load to sample.It is elongated using being pasted onto two simultaneously Foil gauge at the length 1/2 of bar records measured pulse signal.When two elongate rods are always maintained at elastic stage, just It can be according to the communication theory of one-dimensional elastic stress wave, by measured pulse signal in two elongate rods, to calculate The deformation of load and sample itself suffered by sample, to obtain the dynamic mechanics parameter of sample material.
It is mutually same between different types of stress wave in order to realize the multiaxis Combined Loading of material using Hopkinson bar Step is highly important, and especially torsional wave is different from the velocity of wave that tensile wave and compressional wave are propagated in Hopkinson bar how It is also a difficult point so that torsional wave is carried out load to sample simultaneously with compressional wave and tensile wave.But current traditional Hopkinson bar All it is to generate stress wave by way of mechanical load, this generation time for allowing for stress wave cannot be accurately controlled.
In the 1970s, the Hubert A Schmitt et al. in the U.S. study Electromagnetic riveting technology, and Shen Please patent (United States Patent (USP)：On May 7th, 3961739,1974), Zieve Peter et al. are to high-voltage electromagnetic riveting technology later It is improved, has developed low voltage electromagnetic riveting technology (European patent：On May 27th, 0293257,1988).Electromagnetic riveting Operation principle is exactly by increasing coil and an amplifier between discharge coil and workpiece, in the wink that discharge switch is closed Between, in main coil fast-changing current impulse electromagnetic field is generated around coil.The secondary coil coupled with main coil is strong Induced current is generated under magnetic fields, and then generates eddy current magnetism, and two magnetic field interactions generate vortex repulsion, and pass through amplification Device reaches rivet, and rivet is made to be molded.The control time of this technology that shock loading is generated using electromagnetic induction principle is very smart Standard is stronger to output loads amplitude, the controllability of pulsewidth.Therefore, Chinese Patent Application No. is 201420098605.4 Hes In the patent of 201410161610.X, proposes directly apply to electromagnetic riveting unit in Hopkinson pressure bar unit respectively Equipment scheme and experimental method, but the waveform that the method obtains has limitation.It is in Chinese Patent Application No. A kind of stretching based on electromagnetic force and pressure are proposed in 201410173843.1 and 201410171963.8 two innovation and creation Stress under compression wave producer experimental considerations unit and application method, but both scenario-frames are more complicated, and traditional waveform shaping Technology can not be applied to pulled out condition.It is then 201510956545.4 in Chinese Patent Application No. to improve this defect Innovation and creation in, it is proposed that a kind of new load rifle structure, the structure can not only generate tensile wave and compressional wave, but also can be with Shaping is carried out to waveform using traditional Training system.In the innovation and creation that Chinese Patent Application No. is 201510051071, A kind of the main line coil structures and application method of electromagnetic type experimental considerations unit are proposed, to improve width caused by electromagnetic type experimental considerations unit The variation range of value and pulse width.In addition to this, it is proposed in the patent that Chinese Patent Application No. is 201510257557.8 A kind of electromagnetic type torsion bar loading unit, the unit integrate the circuit system of Electromagnetic riveting technology and the operation principle of direct current generator It is used in the stress wave generating unit of split-Hopkinson torsional bar, first charges to a LRC circuit, then electric discharge suddenly makes fixed Subcoil generates instantaneous induced field, and the permanent magnet on rotor will produce electromagnetic force at this time, so that rotor is obtained instantaneous torque, so This instantaneous torque is output to by armature spindle on Hopkinson bar afterwards, to generate a distorting stress wave.Chinese special Application No. is in the patent of 201520325217.X for profit, it is proposed that the load of specific electromagnetic type split-Hopkinson torsional bar loading unit Rifle structure design.For at present, the uniaxial Hopkinson bar experimental technique of electromagnetic drive is already close to maturation, due to electromagnetic drive Control accuracy is high, and the pulsewidth and amplitude controlled range to stress wave are big, this makes the development of multiaxis Hopkinson bar loading system Become feasible.
Invention content
The embodiment provides a kind of dynamic mechanics parameter of material acquisition device and methods, can solve the prior art Stress wave controls the low problem of precision.
The embodiment provides a kind of dynamic mechanics parameter of material acquisition device, including：
Electromagnetic type Hopkinson pressure bar loading unit comprising compressional wave loads rifle and constrictor, wherein compressional wave loads Rifle is used to load compression stress wave to constrictor；
Electromagnetic type split-Hopkinson torsional bar loading unit comprising torsional wave loads rifle and torque rod, wherein torsional wave loads Rifle is used to load distorting stress wave to torque rod, and torque rod is same axis with constrictor；
Stress wave synchronization unit is loaded with electromagnetic type Hopkinson pressure bar loading unit and electromagnetic type split-Hopkinson torsional bar Unit is electrically connected, and loads compression stress wave to constrictor for controlling electromagnetic type Hopkinson pressure bar loading unit, and for controlling Electromagnetic type split-Hopkinson torsional bar loading unit processed loads distorting stress wave to torque rod；
Acquiring unit comprising two compression strain pieces, two torsional strain pieces and data acquisition unit, two compressions are answered Become piece and two torsional strain pieces be connected with data acquisition unit respectively, the dynamic mechanics parameter of material for obtaining sample, In, two compression strain pieces are separately positioned on constrictor surface on torque rod surface, and two torsional strain pieces are respectively set On constrictor surface and on torque rod surface, sample is arranged between constrictor and torque rod and is protected with constrictor and torque rod Hold same axis.
Described two compression strain pieces paste respectively the constrictor and it is described torsion pole length 1/2 at surface on one Place is set in positioning, and for constrictor, the position and constrictor should be greater than 2 times of compressional wave pulsewidth at a distance from sample contacts end Length；For torque rod, the position and torque rod should be greater than 2 times of pressure at a distance from distorting stress wave producer connecting pin Contracting wave pulsewidth length, and the direction that compression strain piece is pasted is identical as rod axis direction, and the compression strain piece is for recording Strain signal when compression stress wave is propagated in bar.
The torsional strain piece is symmetrically pasted onto constrictor and reverses on the surface at pole length 1/2 at certain position, right For constrictor, the position and constrictor should be greater than 2 times of torsional wave arteries and veins at a distance from compression stress wave producer connecting pin Wide length；For torque rod, the torsional wave pulsewidth that the position and torque rod should be greater than 2 times at a distance from sample contacts end is long The direction that degree, wherein torsional strain piece are pasted and rod axis direction angle in an acute angle, the torsional strain piece are turned round for recording Strain signal when turning stress wave is propagated in bar.
The acute angle is 45 °.
The data acquisition unit includes Wheatstone bridge and data collector, wherein compression strain piece and torsional strain Piece accesses in Wheatstone bridge；Wheatstone bridge outputs signal to data collector.
The embodiment of the present invention additionally provides a kind of dynamic mechanics parameter of material acquisition based on claim 1-5 described devices Method, including step：
Load compression stress wave；
Load distorting stress wave；
Obtain the compression stress parameter of sample；
Obtain the distorting stress parameter of sample；
Wherein, the compression stress parameter of sample and the distorting stress parameter of sample are as dynamic mechanics parameter of material.
The compression stress parameter for obtaining sample includes step：
Convert the voltage signal of data acquisition unit records to the strain signal on bar, specific formula is：
The Δs of ε=2 U/k/ (U- Δ U) (1)
Wherein, ε is the strain signal of stress wave, and U is the supply voltage of Wheatstone bridge, and k is compression strain piece sensitivity Coefficient, Δ U are the voltage values of the stress wave signal of data collector record；
It is theoretical using one-dimensional elastic stress wave propagation, the strain signal in bar is handled using a wave method, to obtain The compression stress parameter of sample：
σs=E εTA/As
Wherein,For the compression strain rate of sample, εsFor the compression strain of sample, σsFor the compression stress of sample 7, C0It is The compressional wave velocity of wave of constrictor and torque rod, L are the gauge length segment length of sample, and A is the sectional area of constrictor and torque rod, AsIt is The sectional area of sample, E are the Young's modulus of constrictor and torque rod.
The method further includes the data processing step of the compression stress parameter of sample：With εsFor X-axis, σsIt maps for Y-axis To the stress-strain diagram of sample under compression；Using time t as X-axis, withJust can be obtained for Y-axis sample when m- answer Variability change curve.
The distorting stress parameter for obtaining sample includes step：
Convert the voltage signal that data collector records to the strain signal on bar, specific formula is：
The Δs of ε=2 U/k/ (U- Δ U) (1)
Wherein, ε is the strain signal of distorting stress wave, and U is the supply voltage of Wheatstone bridge, and k is torsional strain piece spirit Sensitivity coefficient, Δ U are the voltage values of the stress wave signal of data collector record；
The material identical that known constrictor is used with torque rod, then the strain signal of torsion transmitted wave is at this time：
γT=2 (ε1-εRcos45°) (3)
Torsion back wave signal be：
γR=2 (ε2-εTcos45°) (4)
Wherein, ε1For the strain signal that the torsional strain piece group on constrictor measures, ε2For the torsional strain piece on torque rod The strain signal measured, εRFor the strain signal of compressive reflexes wave, εTTo compress the strain signal of transmitted wave.
It is theoretical using one-dimensional elastic stress wave propagation, using a wave method to γRAnd γTIt is handled to obtain the torsion of sample Turning stress parameter：
Wherein,For the shear strain rate of sample, γsFor the shear strain of sample, τsFor the shear stress of sample, rsFor The middle radius surface of sample marking distance section, rbFor the radius of constrictor and torque rod, C1It is the torsional wave velocity of wave of constrictor and torque rod, LsIt is the length of sample marking distance section, JbIt is the polar moment of inertia of constrictor and torque rod, JsIt is the polar moment of inertia of sample marking distance section, Gb It is the modulus of shearing of constrictor and torque rod.
The method further includes the data processing step of the distorting stress parameter of sample：With γsFor X-axis, τsIt maps for Y-axis Obtain stress-strain diagram of sample under the conditions of torsion；Using time t as X-axis, withJust can be obtained for Y-axis sample when it is m- Shear strain rate change curve.
The embodiment of the present invention is by by the distorting stress wave generating device and compression stress wave generating device of electromagnetic drive Applied in Hopkinson compression-twisted coupling experiment so that the distorting stress wave and compression stress wave that experimental provision generates exist It is attained by and accurately controls in terms of generation time, pulsewidth and amplitude, and torsion is accurately controlled using high-precision electronic switch The generation time of stress wave and compression stress wave, so as to apply distorting stress wave load and compression stress wave simultaneously to sample Load, sample can not be carried out by overcoming distorting stress wave and compression stress wave caused by mechanical actuation device control accuracy difference The problem of synchronous load.Meanwhile experimental provision accurately controls distorting stress wave and compression stress wave pulsewidth and amplitude, it can So that material is respectively by different size of twisting resistance load and compressing force load, this modeling to material under the conditions of dynamic multiaxis Property mechanical behavior research have very great help.
Description of the drawings
Fig. 1 is the dynamic mechanics parameter of material acquisition device of the embodiment of the present invention；
Fig. 2 is the stress wave synchronization principles figure of the dynamic mechanics parameter of material acquisition device of the embodiment of the present invention.
Drawing reference numeral explanation：
21,31. power supply；2. compressional wave capacitor charger；3. compressional wave loads rifle；4. constrictor；25,35. torsional strain Piece group；26,36. compression strain piece group；7. sample；8. torque rod；9. torsional wave loads rifle；10. torsional wave capacitor charger； 11. data collector；12. stress wave synchronization unit；23,33. control cabinet；14. torsional wave capacitor group；15. compressional wave capacitance Device group.
Specific implementation mode
The present invention is understood and realized for the ease of persons skilled in the art, describes the implementation of the present invention in conjunction with attached drawing Example.
Embodiment one
The dynamic mechanics parameter of material acquisition device of the present invention includes stress-wave loading unit and waveguide lever system.Wherein answer Reeb loading unit includes compression stress wave producer, distorting stress wave producer and stress wave synchronization unit.Wherein compress Stress wave producer is using the loading unit proposed in the patent of invention application No. is 201510956545.4；Distorting stress wave Generator uses electromagnetic type split-Hopkinson torsional bar loading unit；Stress wave synchronization unit is occurred using high-precision digital delay Device.
Synchronous load the present invention relates to distorting stress wave with compression stress wave to sample.Detailed process is：Institute of the present invention The principle of the compression stress wave producer and distorting stress wave producer that are related to all is by power supply to an electric energy storage release Device carries out filling energy, then by switch, electric energy storage release is made to be converted between being charged and discharged two states, to Instantaneous heavy current is generated, load rifle is made to obtain transient load, the load transmission after Hopkinson bar to forming compression stress Wave and distorting stress wave.Velocity of wave when being transmitted in Hopkinson bar with distorting stress wave due to compression stress wave is different, in order to Compression stress wave and distorting stress wave is set to be transmitted to the contact surface of bar and sample from the loading end of bar simultaneously, it is necessary to pass through one in advance Elastic stress theory of wave propagation is tieed up, compression stress wave and distorting stress wave is calculated separately out and is transmitted to bar and examination from the loading end of bar Then time needed for sample contact surface is made the difference again by the two and is calculated between compression stress wave and the propagation time of distorting stress wave Every, then by stress wave synchronization unit with the time interval respectively give compression stress wave producer electric energy store release The electric energy of device and distorting stress wave producer stores release and sends switching signal, to make compression stress wave and distorting stress wave It generates at set time intervals, when compression stress wave and distorting stress wave are transmitted to contact of the bar with sample from the loading end of bar When face, two train waves will simultaneously load sample, add to realize that Hopkinson bar is compound to compression-torsion of material It carries.
The dynamic mechanics parameter of material acquisition device of the present invention includes the identical elongate rod of two root long degree, wherein one is pressure Contracting bar, one is torque rod；Two bars are cylindrical bar, shank diameter 25mm, length 2m；There is connection in wherein torque rod one end The external screw thread of distorting stress wave generating unit.
Present embodiments provide a kind of dynamic mechanics parameter of material acquisition device comprising electromagnetic type Hopkinson pressure bar adds Carrier unit, electromagnetic type split-Hopkinson torsional bar loading unit and stress wave synchronization unit, are below described in detail above-mentioned component.
Electromagnetic type Hopkinson pressure bar loading unit includes power supply 21, and compressional wave capacitor charger 2 and compressional wave load rifle 3；Compressional wave capacitor charger 2 using electromagnetic rivetter power pack, and by the anode of the output of the capacitor charger The electrode line that output line loads rifle 3 with compressional wave connects, and the negative line that negative output line loads rifle with compressional wave connects.
Electromagnetic type split-Hopkinson torsional bar loading unit includes power supply 31, and torsional wave capacitor charger 10 and torsional wave load rifle 9；Torsional wave capacitor charger 10 uses the power pack of a set of electromagnetic rivetter, and the anode of the capacitor charger is defeated Outlet loads the positive terminal of rifle 9 with torsional wave respectively with negative output line and anode connector is connected by conducting wire.
In this example compressional wave capacitor charger 2 and torsional wave capacitor charger 10 by capacitor box and control cabinet 23, 33 are formed.Wherein capacitor box includes a capacitor group and electronic switch.The capacitor group of compressional wave capacitor charger 2 14 are composed in parallel by 10 impulse capacitors, and the rated voltage of the impulse capacitor is 1000V, and capacitance is 200 microfarads；Torsion The capacitor group 15 of wave capacitor charger 10 is composed in parallel by 10 impulse capacitors, and the rated voltage of the impulse capacitor is 10000V, capacitance 6mf.Stress wave synchronization unit 12 by conducting wire respectively with compressional wave capacitor group 14 and torsional wave capacitance Device group 15 is connected, as a switch signal generator, to substitute compressional wave capacitor charger and torsional wave capacitor charger The electronic switch of circuit.Compressional wave capacitor charger 2 and torsional wave capacitor charger 10 use control cabinet of the same race, the control cabinet 23,33 include PLC and its control system.Control system is mainly shown by simulation control part, digital control part and number Part forms.Wherein simulation control part uses the TCA785 chips of SIEMENS companies.Digital control part is by Siemens S7-200 series and Siemens's simulation input output expansion module EM235 compositions.Charging voltage control mainly passes through Voltage loop It is realized with the pid control mode of electric current loop.Digital display portion mainly passes through S7-200 series text display TD200 groups At.
Power supply is all made of the industrial three-phase alternating current of 380V in this example.
Stress wave synchronization unit uses the DG645 type figure delay time generators of SRS companies of the U.S. in this example.
Wherein, compressional wave load rifle 3, constrictor 4, torque rod 8 and torsional wave load rifle 9 are installed successively according to coaxial sequence It can only be moved freely in axis direction on experimental bench, and by the constrictor 4 and torque rod 8.One sample 7 is mounted on Between constrictor 4 and torque rod 8, and keep sample 7 and constrictor 4 and torque rod 8 coaxial.
It is respectively that two panels or multi-disc parameter is identical at about 1/2 position of 8 length of constrictor 4 and torque rod Foil gauge is symmetrically pasted onto the surface of constrictor 4 and torque rod 8, and the wherein direction of strain gauge adhesion is identical as rod axis direction, The strain signal when foil gauge is propagated for recording compressed stress wave in bar, referred to as compression strain piece 26,36；It is described big About 1/2 position refers to, for constrictor, the position and constrictor should be greater than 2 times of compression at a distance from sample contacts end Stress wave pulsewidth length；For torque rod, the position and torque rod are answered at a distance from distorting stress wave producer connecting pin Compression stress wave pulsewidth length more than 2 times.Two panels or the identical foil gauge of multi-disc parameter are symmetrically pasted onto compression again Surface at 8 length 1/2 of bar 4 and torque rod, the wherein direction of strain gauge adhesion and rod axis direction angle at 45 °, it is described to answer Become piece to be used to record strain signal when distorting stress wave is propagated in bar, referred to as torsional strain piece 25,35, torsional strain piece pair Claim to be pasted onto constrictor and reverse on the surface at pole length 1/2 at certain position, for constrictor, the position and compression Bar should be greater than 2 times of torsional wave pulsewidth length at a distance from compression stress wave producer connecting pin；For torque rod, the position It sets with torque rod and should be greater than 2 times of torsional wave pulsewidth length at a distance from sample contacts end.In compression strain piece 26,36 and torsion Welding lead on the pin of foil gauge 25,35 accesses described two foil gauge groups in data collecting system.By the foil gauge Lead is using in twin-core shielding line access Wheatstone bridge.Meanwhile the Wheatstone bridge output signal is shielded using twin-core Line accesses data collector 11.
The embodiment of the invention also discloses a kind of dynamic mechanics parameter of material acquisition methods, including step：Load compression is answered Reeb；Load distorting stress wave；Obtain the compression stress parameter of sample；Obtain the distorting stress parameter of sample；Wherein, sample Compression stress parameter and the distorting stress parameter of sample are as dynamic mechanics parameter of material.Acquisition of the embodiment of the present invention is described below The principle and method of material kinetics parameter.
It is charged respectively to compressional wave capacitor charger 2 and torsional wave capacitor charger 10 using power supply 21,31, wherein Charging voltage must not be higher than the rated voltage of capacitor.After described two capacitor charger electricity are full of, list is synchronized in stress wave The discharge time of setting compressional wave capacitor charger 2 and torsional wave capacitor charger 10, then makes stress wave synchronize list in member 12 To compressional wave capacitor charger 2 and torsional wave capacitor charger 10 switching signal occurs for member respectively with the time set, described Two capacitor chargers start to discharge.
In compression stress wave producer, compressional wave capacitor charger 2 discharges to the main coil of compression-loaded rifle 3, to Make to generate electromagnetic repulsion force between tapered amplifier and main coil, the electromagnetic repulsion force shows as compression inside tapered amplifier and answers Reeb, the compression stress wave form compression incidence wave after being amplified by tapered amplifier and are passed to constrictor 4, when compression incidence wave When reaching the contact surface of constrictor 4 and sample 7, since wave impedance mismatches, the part for compressing incidence wave is reflected, is being compressed Compressive reflexes wave is formed in bar 4；Another part is then transmitted by sample 7 in torque rod 8, and compression transmitted wave is formed.It is described The shape and amplitude of compressive reflexes wave and compression transmitted wave are determined by the property of 7 material of sample.Due to compression strain piece 26 It is connected with Wheatstone bridge, the strain signal in compression strain piece 26 is converted to the bridge arm voltage variation of Wheatstone bridge, number It is connect with Wheatstone bridge by signal wire according to collector 11, the data collector 11 uses calculus of finite differences input to offset electromagnetism Interference.The bridge arm voltage variation of Wheatstone bridge is recorded and is stored by data collector 11.Compression strain wherein on constrictor 4 Piece group 26 will compress incidence wave signal VIWith compressive reflexes wave signal VRIt records；Compression strain piece group 36 on torque rod 8 will Compress transmitted wave signal VTIt records.It converts the voltage signal that data collector 11 records to the strain signal on bar, has Body formula is：
The Δs of ε=2 U/k/ (U- Δ U) (1)
Wherein, ε is the strain signal of stress wave, and U is the supply voltage of Wheatstone bridge, and k is that compression strain piece 26 is sensitive Coefficient is spent, Δ U is the voltage value for the stress wave signal that data collector 11 records.
Pass through formula (1), compression incidence wave signal VIIt is converted into compression incidence wave strain signal εI, compressive reflexes wave signal VRIt is converted into compressive reflexes wave strain signal εR, compression transmitted wave signal VTIt is converted into compression transmitted wave strain signal εT.Utilize one Elastic stress theory of wave propagation is tieed up, the strain signal in bar is handled using a wave method, a wave method formula is as follows：
Wherein,For the compression strain rate of sample 7, εsFor the compression strain of sample 7, σsFor the compression stress of sample 7, C0 It is the compressional wave velocity of wave of constrictor 4 and torque rod 8, L is the gauge length segment length of sample 7, and A is the section of constrictor 4 and torque rod 8 Product, AsIt is the sectional area of sample 7, E is the Young's modulus of constrictor 4 and torque rod 8.
After the completion of data processing, with εsFor X-axis, σsThe stress of sample 7 under compression just can be obtained for Y-axis mapping to answer Varied curve；Using time t as X-axis, withThe when m- strain rate change curve of sample 7 just can be obtained for Y-axis.
In distorting stress wave producer, torsional wave capacitor charger 10 discharges to the stator coil of torsion load rifle 9, from And make to generate electromagnetic repulsion force between the permanent magnet on stator coil and rotor, the electromagnetic repulsion force makes rotor obtain one instantaneously Torque, the instantaneous torque are transmitted on torque rod 8 by armature spindle and form torsion incidence wave.When torsion incidence wave reaches torsion When the contact surface of bar 8 and sample 7, since wave impedance mismatches, the part for reversing incidence wave is reflected, the shape in torque rod 8 At torsion back wave；Another part is then transmitted by sample 7 in constrictor 4, and torsion transmitted wave is formed.The torsion reflection The shape and amplitude of wave and torsion transmitted wave are determined by the property of 7 material of sample.Due to torsional strain piece 36 and favour stone Electric bridge is connected, and the strain signal in torsional strain piece 36 is converted to the bridge arm voltage variation of Wheatstone bridge, data collector 11 are connect by signal wire with Wheatstone bridge, and the data collector 11 uses calculus of finite differences input to offset electromagnetic interference.
The bridge arm voltage variation of Wheatstone bridge is recorded and is stored by data collector 11.Torsion wherein on torque rod 8 Foil gauge 35 will reverse incidence wave signalIt records.It is transmitted to 7 end face of torque rod 8 and sample when reversing incidence wave, then Reflect to form torsion back wave when, torsion back wave with from constrictor 4 transmitted through compression transmitted wave signal it is mixed in together, The torsional strain piece 35 that the mixed signal is transmitted on torque rod causes voltage change V1；Similarly, when torsion transmitted wave transmission When into constrictor 4, reverses transmitted wave and the compressive reflexes wave in constrictor 4 is mixed in together, the mixed signal is transmitted to Torsional strain piece 25 on constrictor 4 causes voltage change V2。
Using formula (1), incidence wave signal will be reversedIt is converted into torsion incidence wave strain signal γI, by mixed signal V1 And V2It is separately converted to strain signal ε1And ε2.Since in constrictor 4, torsion transmits stress wave and compressive reflexes stress at this time Wave signal is mixed in together；In torque rod 8, torsion back wave and compression transmitted wave signal are mixed in together.It therefore will be corresponding to Varying signal ε1And ε2It is decomposed, to obtain really reversing back wave strain signal γ on barRWith torsion transmitted wave strain letter Number γT.The material identical that known constrictor 4 is used with torque rod 8, then the strain signal of torsion transmitted wave is at this time：
γT=2 (ε1-εRcos45°) (3)
Torsion back wave signal be：
γR=2 (ε2-εTcos45°) (4)
Wherein, ε1For the strain signal that the torsional strain piece group on constrictor measures, ε2For the torsional strain piece on torque rod The strain signal measured, εRFor the strain signal of compressive reflexes wave, εTTo compress the strain signal of transmitted wave.
It is theoretical using one-dimensional elastic stress wave propagation, using a wave method to γRAnd γTIt is handled, a wave method formula is such as Under：
Wherein,For the shear strain rate of sample 7, γsFor the shear strain of sample 7, τsFor the shear stress of sample 7, rs For the middle radius surface of 7 gauge length section of sample, rbFor the radius of constrictor 4 and torque rod 8, C1It is the torsion of constrictor 4 and torque rod 8 Wave velocity of wave, LsIt is the length of 7 gauge length section of sample, JbIt is the polar moment of inertia of constrictor 4 and torque rod 8, JsIt is 7 gauge length section of sample Polar moment of inertia, GbIt is the modulus of shearing of constrictor 4 and torque rod 8.
After the completion of data processing, with γsFor X-axis, τsStress of the sample 7 under the conditions of torsion just can be obtained for Y-axis mapping to answer Varied curve；Using time t as X-axis, withThe when m- shear strain rate change curve of sample 7 just can be obtained for Y-axis.
The electromagnetic type Hopkinson that the electromagnetic type Hopkinson pressure bar loading unit of the present invention could alternatively be the present invention is drawn Bar loading unit.
The distorting stress wave generating device of electromagnetic drive and compression stress wave generating device are applied to Hope's gold by the present invention In gloomy compression-twisted coupling experiment so that the distorting stress wave and compression stress wave that experimental provision generates are in generation time, pulsewidth And be attained by and accurately control in terms of amplitude, and accurately control distorting stress wave using high-precision electronic switch and compression is answered The generation time of Reeb overcomes machine so as to apply distorting stress wave load and compression stress wave load simultaneously to sample Distorting stress wave and compression stress wave caused by tool driving device control accuracy difference can not synchronize load to sample and ask Topic.Meanwhile experimental provision accurately controls distorting stress wave and compression stress wave pulsewidth and amplitude, material can be made to distinguish By different size of twisting resistance load and compressing force load, this grinds plasticity behavior of material under the conditions of dynamic multiaxis Study carefully and has very great help.
Although depicting the present invention by embodiment, it will be appreciated by the skilled addressee that not departing from the present invention's In the case of spirit and essence, so that it may make the present invention there are many deformation and variation, the scope of the present invention is by the attached claims To limit.

Claims (10)

1. a kind of dynamic mechanics parameter of material acquisition device, which is characterized in that including：
Electromagnetic type Hopkinson pressure bar loading unit comprising compressional wave loads rifle and constrictor, wherein compressional wave loads rifle and uses In to constrictor load compression stress wave；
Electromagnetic type split-Hopkinson torsional bar loading unit comprising torsional wave loads rifle and torque rod, wherein torsional wave loads rifle and uses In loading distorting stress wave to torque rod, torque rod is same axis with constrictor；
Stress wave synchronization unit, with electromagnetic type Hopkinson pressure bar loading unit and electromagnetic type split-Hopkinson torsional bar loading unit Electrical connection loads compression stress wave for controlling electromagnetic type Hopkinson pressure bar loading unit to constrictor, and for controlling electricity Magnetic-type split-Hopkinson torsional bar loading unit loads distorting stress wave to torque rod；
Acquiring unit comprising two compression strain pieces, two torsional strain pieces and data acquisition unit, two compression strain pieces It is connected respectively with data acquisition unit with two torsional strain pieces, the dynamic mechanics parameter of material for obtaining sample, wherein two A compression strain piece is separately positioned on constrictor surface on torque rod surface, and two torsional strain pieces are separately positioned on compression On on bar surface and torque rod surface, sample is arranged between constrictor and torque rod and keeps same with constrictor and torque rod Axis.
2. dynamic mechanics parameter of material acquisition device according to claim 1, which is characterized in that described two compression strains Piece is pasted respectively on the surface at the 1/2 of the constrictor and the torsion pole length at certain position, for constrictor, The position and constrictor are more than 2 times of compressional wave pulsewidth length at a distance from sample contacts end；For torque rod, the position It is more than 2 times of compressional wave pulsewidth length, and compression strain piece at a distance from distorting stress wave producer connecting pin with torque rod The direction of stickup is identical as rod axis direction, the strain when compression strain piece is propagated for recording compressed stress wave in bar Signal.
3. dynamic mechanics parameter of material acquisition device according to claim 1, which is characterized in that the torsional strain piece pair Claim to be pasted onto constrictor and reverse on the surface at pole length 1/2 at certain position, for constrictor, the position and compression Bar is more than 2 times of torsional wave pulsewidth length at a distance from compression stress wave producer connecting pin；For torque rod, the position Be more than 2 times of torsional wave pulsewidth length at a distance from sample contacts end with torque rod, the direction that wherein torsional strain piece is pasted with Rod axis direction angle in an acute angle, the torsional strain piece are used to record strain letter when distorting stress wave is propagated in bar Number.
4. dynamic mechanics parameter of material acquisition device according to claim 3, which is characterized in that the acute angle is 45°。
5. dynamic mechanics parameter of material acquisition device according to claim 1, which is characterized in that the data acquisition unit Including Wheatstone bridge and data collector, wherein in compression strain piece and torsional strain piece access Wheatstone bridge；Favour stone Bridge output signal is to data collector.
6. a kind of dynamic mechanics parameter of material acquisition methods based on claim 1-5 described devices, which is characterized in that including step Suddenly：
Load compression stress wave；
Load distorting stress wave；
Obtain the compression stress parameter of sample；
Obtain the distorting stress parameter of sample；
Wherein, the compression stress parameter of sample and the distorting stress parameter of sample are as dynamic mechanics parameter of material.
7. according to the method described in claim 6, it is characterized in that, the compression stress parameter for obtaining sample includes step：
Convert the voltage signal of data acquisition unit records to the strain signal on bar, specific formula is：
The Δs of ε=2 U/k/ (U- Δ U) (1)
Wherein, ε is the strain signal of compression stress wave, and U is the supply voltage of Wheatstone bridge, and k is compression strain piece sensitivity Coefficient, Δ U are the voltage values of the stress wave signal of data collector record；
It is theoretical using one-dimensional elastic stress wave propagation, using a wave method to the strain signal in constrictor and torque rod at Reason, to obtain the compression stress parameter of sample：
Wherein,For the compression strain rate of sample, εsFor the compression strain of sample, σsFor the compression stress of sample 7, C0It is constrictor With the compressional wave velocity of wave of torque rod, L is the gauge length segment length of sample, and A is the sectional area of constrictor and torque rod, AsIt is sample Sectional area, E are the Young's modulus of constrictor and torque rod.
8. the method according to the description of claim 7 is characterized in that the method further includes the number of the compression stress parameter of sample According to processing step：With εsFor X-axis, σsIt maps to obtain the stress-strain diagram of sample under compression for Y-axis；It is X with time t Axis, withThe when m- strain rate change curve of sample just can be obtained for Y-axis.
9. according to the method described in claim 6, it is characterized in that, the distorting stress parameter for obtaining sample includes step：
Convert the voltage signal that data collector records to the strain signal on bar, specific formula is：
The Δs of ε=2 U/k/ (U- Δ U) (1)
Wherein, ε is the strain signal of distorting stress wave, and U is the supply voltage of Wheatstone bridge, and k is torsional strain piece sensitivity Coefficient, Δ U are the voltage values of the stress wave signal of data collector record；
The material identical that known constrictor is used with torque rod, then the strain signal of torsion transmitted wave is at this time：
γT=2 (ε1-εRcos45°) (3)
Torsion back wave signal be：
γR=2 (ε2-εTcos45°) (4)
Wherein, ε1For the strain signal that the torsional strain piece group on constrictor measures, ε2It is measured for the torsional strain piece on torque rod Strain signal, εRFor the strain signal of compressive reflexes wave, εTTo compress the strain signal of transmitted wave；
It is theoretical using one-dimensional elastic stress wave propagation, using a wave method to γRAnd γTIt is handled and is answered with the torsion for obtaining sample Force parameter：
Wherein,For the shear strain rate of sample, γsFor the shear strain of sample, τsFor the shear stress of sample, rsFor sample mark Middle radius surface away from section, rbFor the radius of constrictor and torque rod, C1It is the torsional wave velocity of wave of constrictor and torque rod, LsIt is examination The length of sample gauge length section, JbIt is the polar moment of inertia of constrictor and torque rod, JsIt is the polar moment of inertia of sample marking distance section, GbIt is compression The modulus of shearing of bar and torque rod.
10. according to the method described in claim 9, it is characterized in that, the method further includes the distorting stress parameter of sample Data processing step：With γsFor X-axis, τsIt maps to obtain stress-strain diagram of sample under the conditions of torsion for Y-axis；With time t For X-axis, withThe when m- shear strain rate change curve of sample just can be obtained for Y-axis.
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CN111579404A (en) * 2020-05-21 2020-08-25 西北工业大学 Dynamic uniaxial bidirectional compression experimental method for brittle material
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