CN111665152A - Material dynamic compression circulating loading device and method thereof - Google Patents
Material dynamic compression circulating loading device and method thereof Download PDFInfo
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- 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
- G01N3/36—Investigating strength properties of solid materials by application of mechanical stress by applying repeated or pulsating forces generated by pneumatic or hydraulic means
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- G01N2203/0001—Type of application of the stress
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- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
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- G01N2203/0019—Compressive
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- 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
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Abstract
The invention discloses a material dynamic compression cycle loading device and a method thereof, wherein the device comprises: the device comprises a striking rod, a waveform shaper, an incident rod and a transmission rod which are coaxially and sequentially arranged; a sample is arranged between the incident rod and the transmission rod and is made of a polymer material; the impact rod impacts the near end of the incident rod to generate incident stress waves, and the waveform shaper filters and shapes the incident stress waves; the incident stress wave is transmitted along the incident rod to load the sample, one part of the incident stress wave forms a reflected stress wave in the incident rod, and the other part of the incident stress wave is transmitted into the transmission rod through the sample to form a transmitted stress wave; the length of the transmission rod is at least 2 times of that of the incident rod, and the diameter of the transmission rod is smaller than that of the incident rod; the reflected stress wave is transmitted to the near end of the incident rod and reflected to become the incident stress wave of the second loading, and the sample is loaded for the second time, so that the sample is loaded circularly.
Description
Technical Field
The invention relates to a dynamic mechanical property testing technology of a material, in particular to a dynamic compression cycle loading device and a dynamic compression cycle loading method of the material.
Background
Elastomer materials such as rubber are subjected to dynamic cyclic loading in a working service environment, for example, the rubber is used as a buffering and damping device in dynamic energy absorption application and is used as a key component of a tire in high-speed running of an automobileThe driving process is subject to dynamic cycle working conditions, and the loading time is in the order of milliseconds or even sub-millimeter. In the research of elastomers such as rubber, the mechanical response of rubber materials such as damage behavior is described by the marins effect (Mullinseffect), and the softening phenomenon of the elastomer materials such as rubber, during the loading process, is called as the marins effect, wherein the subsequent loading stiffness is smaller than the initial loading stiffness. This is the softening of the material due to the material being deformed by an external force and being damaged inside. For the measurement problem of the Marins effect of the material, the traditional method is to carry out loading-unloading-reloading cyclic reciprocating loading on a sample by controlling a quasi-static mechanics testing machine program to obtain a stress-strain curve of the material under cyclic loading-unloading, and carry out analytical research on the mechanical response and damage evolution characteristics of the material by combining a hysteresis loop in the curve. The dynamic cyclic load environment of the real service environment, the strain rate related to materials such as rubber and the like is 101s-1～103s-1To this end, similar experiments based on existing mechanical testing machines have the following difficulties:
(1) the sample loading/unloading process is in the microsecond or even sub-microsecond order, and in the instant process, the load is loaded on the sample in the form of stress waves, and the stress waves can be reflected and transmitted for many times in a sample clamp and a load sensor of a testing machine, so that the load history in the sample deformation process is difficult to acquire and record with high precision.
(2) The sample loading chuck is overloaded too much, so that the test precision of the sample deformation displacement is limited. The specific analysis is as follows: developing 10 on the basis of a universal mechanical testing machine1s-1～103s-1The test machine fixture or pressure head changes in speed in microsecond order from static loading to a certain preset speed, for example ASTM D412-98 a (2002) Die C model, the length of the gauge length of the test sample is 33mm, if 10 is developed1s-1～103s-1Strain rate loading, fixture pressure head speed is: 0.33m/s to 33 m/s. If the acceleration process is calculated for 1ms, the chuck overload is as follows: 33.67 to 3367.35g (g is 9.8 m/s)2) This is a typical impact overload environment. In the ideal additionDuring loading, the chuck is accelerated to a specified speed and then a constant speed loading/unloading process is carried out for a sufficient period of time, and the actual overload characteristic is much higher than that.
At present, in the field of research on material mechanics, the split hopkinson pressure bar technology based on stress wave loading is the most widely used technology for testing the mechanical properties of materials under high strain rate. The basic principle of this method is: the sample is placed between the two pressure rods, and compression stress waves are generated in the incident rod in a mechanical impact mode, so that the sample is loaded. Stress wave signals are recorded through the strain gauge adhered to the compression bar, and the strain gauge is combined with a high-speed data acquisition instrument to acquire and record for subsequent data analysis. The existing Hopkinson pressure bar experimental equipment and loading technology can only carry out single loading on a sample to obtain a stress-strain curve of a material under a certain high strain rate, and can not realize multiple continuous high strain rate cyclic loading of the material, namely the Marins effect of the material under the high strain rate can not be realized through the traditional Hopkinson bar experimental technology.
Disclosure of Invention
The invention mainly aims to provide a material dynamic compression cyclic loading device and a material dynamic compression cyclic loading method, and aims to solve the problems that the prior art can not carry out controllable repeated continuous high-strain-rate cyclic loading on a material, or the Marins effect of the material under the high strain rate can not be realized through the traditional Hopkinson bar experiment technology.
According to an aspect of an embodiment of the present invention, a material dynamic compression cycle loading device is provided, which includes: the device comprises a striking rod, a waveform shaper, an incident rod and a transmission rod which are coaxially and sequentially arranged; wherein a sample is arranged between the incident rod and the transmission rod, and the sample is made of a polymer material; the impact rod impacts the proximal end of the incident rod to generate an incident stress wave, wherein the wave shaper filter-shapes the incident stress wave; the incident stress wave is transmitted along the incident rod to load the sample, one part of the incident stress wave forms a reflection stress wave in the incident rod, and the other part of the incident stress wave is transmitted into the transmission rod through the sample to form a transmission stress wave; wherein the length of the transmission rod is at least 2 times of the length of the incident rod, and the diameter of the transmission rod is smaller than that of the incident rod; and the reflected stress wave is transmitted to the near end of the incident rod and reflected to be the incident stress wave loaded for the second time, and the sample is loaded for the second time, so that the sample is loaded circularly.
And the sample deforms after being loaded, the sample deforms and recovers before the next loading, and stress wave signals which follow the incident stress wave and the transmission stress wave are respectively generated in the sample deformation and recovery process.
The device further comprises a first strain gauge arranged on the incident rod and a second strain gauge arranged on the transmission rod; the first strain gauge collects the incident stress wave signal, the reflected stress wave signal and the stress wave signal, and the second strain gauge collects the transmitted stress wave signal and the stress wave signal.
The impact rod and the incident rod are made of the same material and have the same diameter, and the length of the incident rod is at least 2 times that of the impact rod.
Wherein the density and elastic modulus of the incident rod are greater than those of the transmission rod.
According to another aspect of the embodiments of the present invention, there is also provided a material dynamic compression cycle loading method, including: the impact rod, the waveform shaper, the incident rod and the transmission rod are coaxially and sequentially arranged; arranging a sample between the incident rod and the transmission rod, wherein the sample is made of a polymer material; striking the striker rod against the proximal end of the incident rod to generate an incident stress wave, wherein the wave shaper filter shapes the incident stress wave; the incident stress wave is transmitted along the incident rod to load the sample, one part of the incident stress wave forms a reflected stress wave in the incident rod, and the other part of the incident stress wave is transmitted into the transmission rod through the sample to form a transmitted stress wave; wherein the length of the transmission rod is at least 2 times greater than that of the incident rod, and the diameter of the transmission rod is smaller than that of the incident rod; and the reflected stress wave is transmitted to the near end of the incident rod and reflected to be the incident stress wave loaded for the second time, and the sample is loaded for the second time, so that the sample is loaded circularly.
Wherein the method further comprises: the specimen deforms after being loaded and returns to shape before the next loading.
Wherein the method further comprises: the method comprises the steps that a first strain gauge is arranged on an incidence rod, a second strain gauge is arranged on a transmission rod, wherein the first strain gauge collects incident stress wave signals, reflected stress wave signals and stress wave signals, and the second strain gauge collects transmitted stress wave signals and stress wave signals.
The impact rod and the incident rod are made of the same material and have the same diameter, and the length of the incident rod is at least 2 times that of the impact rod.
Wherein the density and elastic modulus of the incident rod are greater than those of the transmission rod.
According to the technical scheme of the invention, through one-time impact on the incident rod, the polymer material or the soft material can be subjected to stress wave undamped cyclic loading, and the method can be used for testing the dynamic mechanical property of the material in the Marsdellin effect.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the invention without limiting the invention. In the drawings:
FIG. 1 is a schematic diagram of a material dynamic compression cycle loading apparatus according to an embodiment of the present invention;
FIG. 2 is a waveform diagram of a stress wave according to an embodiment of the present invention;
FIG. 3 is a flow chart of a method of dynamic compression cycling loading of a material according to an embodiment of the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the specific embodiments of the present invention and the accompanying drawings. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The technical solutions provided by the embodiments of the present invention are described in detail below with reference to the accompanying drawings.
The invention can be used for testing the dynamic mechanical property of polymer materials with elasticity such as rubber, especially for testing the Marins effect such as damage behavior of the polymer materials in the transient process of microsecond or even sub-microsecond order, and can collect and record the load data of the sample in the process of loading/unloading deformation with high precision.
According to an embodiment of the present invention, there is provided a material dynamic compression cyclic loading device, referring to fig. 1, the cyclic loading device at least includes: the device comprises a striker rod 1, a waveform shaper 2, an incident rod 3 and a transmission rod 7, wherein a sample 5 is arranged between the incident rod 3 and the transmission rod 7. Wherein, the impact rod 1, the wave shaper 2, the incident rod 3, the sample 5 and the transmission rod 7 are coaxially arranged in sequence.
The impact rod 1 is a cylindrical long straight rod with a certain length, and the impact rod 1 can be made of a high-strength metal elastic rod. The impact rod 1 can be accelerated and impacted on the end face of the near end of the incident rod 3 in a compressed air or electromagnetic driving mode, and stress waves are generated on the end face so as to mechanically load the test sample 5.
The incident rod 3 can also be called as an incident wave guide rod, the incident rod 3 is a cylindrical long straight rod with a certain length, the incident rod 3 can be made of a high-strength metal material and used for transmitting incident stress waves and reflected stress waves, the incident waves are transmitted from the near end to the far end of the incident rod 3, and the reflected waves are transmitted from the far end to the near end of the incident rod 3. In the embodiment of the present application, the incident rod 3 and the striker rod 1 may be the same high strength metal material, the same diameter elastic rod, and the length of the incident rod 3 is much longer than that of the striker rod 1, for example, the length of the incident rod 3 is at least 2 times longer than that of the striker rod 1.
The wave shaper 2 is arranged at the near end of the incident rod 3, and the wave shaper 2 can be made of low-impedance materials such as red copper, soft aluminum or rubber materials. The wave shaper 2 is connected with the end face of the near end of the incident rod 3, and the impact rod 1 is contacted with the end face of the incident rod 3 to generate incident wavefront, so that deformation energy absorption is performed, and the generated incident wave is filtered and shaped. Specifically, the wave shaper 2 filters out the high frequency oscillating portion of the incident wave, thereby generating a short duration, large amplitude and smooth-curved incident stress wave.
The sample 5 is held or disposed between the incident rod 3 and the transmission rod 7, and the sample 5 may be made of a polymer material having elasticity such as rubber, wherein the polymer material has a large recovery capability after being deformed, that is, the polymer material can be rapidly recovered to a shape before being deformed after being deformed.
The transmission rod 7 is opposite to the incident rod 3, the transmission rod 7 being used for conducting a transmitted stress wave continuously loaded on the test specimen 5, and the transmission rod 7 being further used for conducting a stress wave generated during the deformation recovery of the pattern 5, the stress wave following the transmitted stress wave. In the embodiment of the present application, the transmission rod 7 can be made of a plexiglas rod with low impedance or a plexiglas tube with a closed proximal end.
It should be noted that the diameter of the transmission rod 7 is smaller than that of the incident rod 3, the length of the transmission rod 7 is at least two times greater than that of the incident rod 3, and both the density and the elastic modulus of the incident rod 3 are greater than those of the transmission rod 7.
When loaded, the striker rod 1 is accelerated to strike the wave shaper 2 at a predetermined velocity to generate a compression stress wave of a certain amplitude and pulse width on the incident rod 3 and propagate along the waveguide rod 3. When the stress wave is conducted to the contact surface of the waveguide rod 3 and the sample 5, because the wave impedances of the waveguide rod 3 and the sample 5 are not matched, the characteristic of the Hopkinson rod when the sample is loaded is shown, namely, a part of incident wave is reflected to form a reflected wave on the incident rod 3, and the other part of incident wave is transmitted into the transmission rod 7 through the sample 5 to form a transmission wave.
After the incident wave loading is completed, the deformed sample 5 is deformed in a recovery manner due to the existence of the restoring force, which is equivalent to the unloading process in the cyclic loading, namely, the stress wave following the reflected wave and the transmitted wave is generated in the process. When the reflected wave propagates to the near end of the incident rod 3, the reflected wave is completely reflected by the near end face to become a compression stress wave, the compression stress wave is expressed as the incident wave characteristic and loads the sample 5 again, and then the reflected wave and the transmitted wave are generated again, so that the loading-unloading-cyclic loading of the sample 5 is realized.
Because the wave impedance of the sample 5 is far lower than that of the incident rod 3 with high impedance and large diameter and metal texture, based on the theoretical knowledge of stress waves, the attenuation of the reflected wave amplitude is less or negligible compared with that of the incident wave at the previous time, and therefore, the intermittent repeated constant-amplitude stress wave loading on the sample material can be realized.
Referring to fig. 2, further, the transmission stress wave and the recovery stress wave of the sample during the loading-unloading cyclic loading process can be acquired by the transmission rod strain gauge with high accuracy without interference. This application is through setting up the foil gage signal collection on the wave guide pole. The strain gauges can respectively convert strain changes on the two rods into resistance changes, and further convert the resistance changes into output voltage changes of two bridge arms of a Wheatstone half bridge, and the voltage changes are input into the data acquisition unit through the two shielding signal wires. The strain gauge arranged on the transmission rod can acquire signals under the loading process of at least 4 loading-unloading cycles.
The loading process of the present application is described in detail below in conjunction with fig. 3.
Step 1, equipment is arranged.
The whole loading device is arranged on the same horizontal line, the impact rod, the waveform shaper, the incident waveguide rod and the transmission waveguide rod are coaxially arranged in sequence (step S302), each waveguide rod can freely move in the axial direction, a sample to be tested is placed between the two waveguide rods (step S304), and the axial line of the sample is coaxial with the waveguide rods. The method for pasting the strain gauge can adopt the prior art, and a pair of strains with identical parameters are symmetrically pasted on the surface of the waveguide rod along the axis on the waveguide rod.
In this embodiment, the impact rod 1 and the incident rod 3 are both made of 1Cr18Ni high-strength steel, the length of the incident rod 3 is 1m, the length of the impact rod 1 is 40cm, the diameters of the impact rod 1 and the incident rod 3 are both 19mm, the yield strength is 1600MPa, and the dynamic mechanical loading test method is suitable for dynamic mechanical loading test research of almost all engineering materials. The signal acquisition of the incident waveguide rod adopts a metal strain gauge with the resistance value of 1000 ohms and the sensitivity coefficient of 2.0; the transmission rod 7 is an organic glass rod, the length of the transmission rod is 4m, the diameter of the transmission rod is 19mm, and transmission stress wave collection with the duration of 3.8ms can be achieved. And a semiconductor strain gauge with the resistance value of 120 ohms and the sensitivity coefficient of 110 is adopted on the transmission wave guide rod, a strain gauge lead is welded on a pin of the strain gauge, and the strain gauge is respectively connected into two opposite bridge arms of the Wheatstone half bridge through leads. The fixed resistors on the other two arms of the Wheatstone half bridge are connected with the incident waveguide rod by 1000 ohms, the power supply voltage of the Wheatstone half bridge is 30V direct current voltage, the fixed resistors connected with the transmission waveguide rod by 120 ohms, and the power supply voltage is 5V direct current voltage. Two diagonal voltages of the Wheatstone half bridge are input to the data acquisition unit through two conventional single-core shielding signal wires.
And 2, setting experimental parameters.
In the embodiment, the impact rod is driven by high-pressure gas to generate stress waves. The length of the impact rod is selected to be a mm according to the experimental use of the loading pulse width, wherein the relationship between a and the stress wave pulse width is generally: b 2a/c
Where b represents the stress wave pulse width and c represents the wave velocity of the stress wave propagating in the incident waveguide rod.
The amplitude of the added carrier wave is used according to the experiment, and a required air pressure value xV is input, wherein x represents the required air pressure value and is within the rated range of the high-pressure air chamber.
And 3, inflating the high-pressure air chamber.
After the parameters are set, the mechanical knob is twisted, high-pressure gas is filled into the gas chamber through the high-pressure gas cylinder, and the impact rod is driven to store energy. After reaching the preset air pressure, the knob is closed to stop air inflation, and the air pressure of the air chamber is not increased.
And 4, generating stress waves by impact of the impact rod.
After the high-pressure air chamber is inflated, the launching knob is started to enable the high-pressure air to drive the impact rod to impact the end face of the incident waveguide rod along the guide rail (step S306). Before the wave guide rod completely collides with the incident wave guide rod, the wave shaper deforms to absorb energy, and an incident stress wave with short duration and large amplitude is generated on the end face of the incident wave guide rod. The incident stress wave is transmitted to the sample from the far end of the waveguide rod, when the incident wave is transmitted to the contact surface of the waveguide rod and the sample, one part of the incident wave is reflected due to the mismatching of wave impedance to form a reflected wave in the waveguide rod, the other part of the incident wave is transmitted into the transmitted waveguide rod through the sample to form a transmitted wave, and the shapes and amplitudes of the reflected wave and the transmitted wave are determined by the material properties of the sample. After the incident wave loading is finished, the deformed sample can be deformed again due to the restoring force of the sample, which is equivalent to the unloading process in cyclic loading, namely, stress waves following the reflected waves and the transmitted waves are generated in the process. When the reflected wave is transmitted to the impact end of the incident rod, the reflected wave is completely reflected into compression wave through the end face, the sample is loaded again through the incident wave characteristic, and then the reflected wave and the transmitted wave are generated again, so that the loading-unloading cyclic loading of the sample is realized. Because the wave impedance of the sample is far lower than that of the metal incident rod with high impedance and large diameter, based on the theoretical knowledge of stress waves, the attenuation of the amplitude of the reflected wave is less than that of the incident wave at the previous time, and therefore, the intermittent repeated constant-amplitude stress wave loading on the sample material can be realized. The required transmission rod is at least twice the length of the incident rod, and the material is a light polymer round rod such as an organic glass rod, so that the transmission stress wave and the recovery stress wave of the sample in the loading-unloading cyclic loading process can be acquired by the transmission rod strain gauge in an interference-free high-precision manner.
And 5, acquiring and processing experimental data.
The strain gauges on the waveguide rods can respectively convert strain changes on the two rods into resistance changes, and further convert the resistance changes into changes of output voltages of two bridge arms of a Wheatstone half bridge, and the voltage changes are input into a data acquisition unit through two conventional shielding signal wires. According to the Wheatstone bridge formula, the strain signal of the waveguide rod can be calculated as follows:
＝2ΔU/(U0-ΔU)/k (1)
wherein, representing a strain signal, U0The power supply voltage of the wheatstone half bridge is shown, k the sensitivity coefficient of the strain gauge, and Δ U the change value of the bridge arm voltage of the wheatstone half bridge with time.
Based on the strain gage position and rod length configuration shown in fig. 1 for the device configuration, the strain gage on the transmission rod can acquire signals at least during 4 load-unload cycles.
In the experiment loading process, the first-column incident stress wave returns after loading the sample, and the sample is loaded for the second time along the waveguide rod after being reflected by the free end surface, so that the loading-unloading cyclic loading of the sample is realized. Because the wave impedance of the sample is far lower than that of the metal incident rod with high impedance and large diameter, based on the theoretical knowledge of stress waves, the attenuation of the amplitude of the reflected wave is less than that of the incident wave at the previous time, and therefore, the intermittent repeated constant-amplitude stress wave loading on the sample material can be realized. In the process, stress wave signals on the waveguide rod are collected through the strain gauge, incident wave signals, reflected waves and transmitted wave signals are recorded by the data collector, and the internal stress of the sample can be obtained by using a one-dimensional stress wave theory as follows:
wherein σSDenotes the internal stress of the sample, E denotes the modulus of elasticity of the waveguide rod, A denotes the cross-sectional area of the waveguide rod, AsShowing the cross-sectional area of the sample corresponding to the direction of loading,irepresenting the incident wave signal on the incident waveguide rod,rrepresenting the reflected wave signal obtained on the incident waveguide rod,trepresenting the resulting transmitted wave signal on the transmitted waveguide rod.
And obtaining a stress-strain curve of the sample through data processing: and (3) calculating the stress of the sample and the strain of the measured sample according to the formula (2), and drawing a graph by taking the strain of the sample as an x axis and the stress as a y axis to obtain a stress-strain curve of the sample.
For the strain in the sample, a strain gage can be pasted on the surface of the sample to directly measure the internal strain; or using a high-speed camera and employing DIC techniques to calculate the strain inside the sample.
The operation steps of the method of the present invention correspond to the structural features of the device, and may be referred to one another, and are not described in detail.
The invention has at least the following technical effects:
(1) in the aspect of loading, a stress wave cyclic loading mode is adopted, so that stress wave non-attenuation cyclic loading can be carried out on a polymer material or a soft material, and the method can be used for testing the dynamic mechanical property of the material in the Marsdrin effect;
(2) in the aspect of result acquisition, an incident waveguide rod and a transmission waveguide rod which are made of different materials are adopted, the length of the transmission waveguide rod is far larger than that of the incident waveguide rod, and a plurality of cyclic stress wave loads can be collected.
It should be noted that in the description of the present invention, unless explicitly specified or limited otherwise, the term "stress wave" is to be understood in a broad sense, e.g. as a transient pulse, as well as a carrier wave. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
As will be appreciated by one skilled in the art, embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.
The above description is only an example of the present invention, and is not intended to limit the present invention, and it is obvious to those skilled in the art that various modifications and variations can be made in the present invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.
Claims (10)
1. A material dynamic compression cycle loading device is characterized by comprising: the device comprises a striking rod, a waveform shaper, an incident rod and a transmission rod which are coaxially and sequentially arranged; wherein a sample is arranged between the incident rod and the transmission rod, and the sample is made of a polymer material;
the impact rod impacts the proximal end of the incident rod to generate an incident stress wave, wherein the wave shaper filter-shapes the incident stress wave;
the incident stress wave is transmitted along the incident rod to load the sample, one part of the incident stress wave forms a reflection stress wave in the incident rod, and the other part of the incident stress wave is transmitted into the transmission rod through the sample to form a transmission stress wave; wherein the length of the transmission rod is at least 2 times of the length of the incident rod, and the diameter of the transmission rod is smaller than that of the incident rod;
and the reflected stress wave is transmitted to the near end of the incident rod and reflected to be the incident stress wave loaded for the second time, and the sample is loaded for the second time, so that the sample is loaded circularly.
2. The apparatus of claim 1 wherein said specimen is deformed after being loaded and said specimen is deformed to recover before the next loading, said pattern deformation recovery producing stress wave signals that follow said incident stress wave and said transmitted stress wave, respectively.
3. The device of claim 2, further comprising a first strain gauge disposed on the entrance rod and a second strain gauge disposed on the transmission rod; the first strain gauge collects the incident stress wave signal, the reflected stress wave signal and the stress wave signal, and the second strain gauge collects the transmitted stress wave signal and the stress wave signal.
4. The device of claim 1, wherein the striker bar and the entrance bar are made of the same material and have the same diameter, and the entrance bar has a length at least 2 times the length of the striker bar.
5. The device of claim 1, wherein the incident rod has a density and elastic modulus greater than the density and elastic modulus of the transmissive rod.
6. A material dynamic compression cycle loading method is characterized by comprising the following steps:
the impact rod, the waveform shaper, the incident rod and the transmission rod are coaxially and sequentially arranged;
arranging a sample between the incident rod and the transmission rod, wherein the sample is made of a polymer material;
striking the striker rod against the proximal end of the incident rod to generate an incident stress wave, wherein the wave shaper filter shapes the incident stress wave;
the incident stress wave is transmitted along the incident rod to load the sample, one part of the incident stress wave forms a reflected stress wave in the incident rod, and the other part of the incident stress wave is transmitted into the transmission rod through the sample to form a transmitted stress wave; wherein the length of the transmission rod is at least 2 times greater than that of the incident rod, and the diameter of the transmission rod is smaller than that of the incident rod;
and the reflected stress wave is transmitted to the near end of the incident rod and reflected to be the incident stress wave loaded for the second time, and the sample is loaded for the second time, so that the sample is loaded circularly.
7. The method of claim 6, further comprising: the specimen deforms after being loaded and returns to shape before the next loading.
8. The method of claim 7, further comprising:
the method comprises the steps that a first strain gauge is arranged on an incidence rod, a second strain gauge is arranged on a transmission rod, wherein the first strain gauge collects incident stress wave signals, reflected stress wave signals and stress wave signals, and the second strain gauge collects transmitted stress wave signals and stress wave signals.
9. The method of claim 6, wherein the striker bar and the incident bar are made of the same material and have the same diameter, and the length of the incident bar is at least 2 times the length of the striker bar.
10. The method of claim 6, wherein the incident rod has a density and elastic modulus greater than the density and elastic modulus of the transmissive rod.
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