Material high-strain-rate multi-scene coupling loading experiment device and method

Abstract

The invention relates to a material high-strain-rate multi-scene coupling loading experiment device and method, and the device is used for detecting the strain rate of a material sample, and comprises a power assembly which is used for providing power required by a coupling loading experiment; the environment assembly is used for providing an environment required by a coupling loading experiment; the characterization assembly is used for applying stress to the material sample, and the material sample is arranged in the characterization assembly and the environment assembly; the axial pressure assembly is used for ensuring normal operation of the characterization assembly in the axial direction; and the detection assembly is used for measuring and calculating the strain rate of the material sample after detecting the impact data. Static compression prestress load can be applied to a dynamic compression test sample, so that research and test of dynamic compression strength and damage characteristics of materials such as wood, rock soil and magnesium alloy are closer to environmental conditions for real use of the materials. Therefore, the test result is more accurate and reliable, and the defect that the existing device can only carry out the dynamic compression test of the sample in a normal environment is overcome.

Description

Technical Field

[0001] The present invention relates to the technical field of testing the dynamic mechanical properties of materials, and particularly to an experimental device and method for coupling multi-scenario loading of materials at high strain rates. Background Art

[0002] An experimental device for coupling high strain rate force-thermal-humidity multi-physical field loading and performance characterization of materials is a device for testing the mechanical properties of materials, which can load specimens in a coupled temperature and humidity environment. The main reasons for manufacturing such a device are as follows:

[0003] Simulating the real environment: Aircraft and spacecraft will encounter drastic temperature changes, high humidity, and dynamic loading during flight, all of which require materials to have excellent resistance to heat and humidity and anti-dynamic loading performance. The track structure of high-speed railways will be subjected to periodic dynamic loading by high-speed trains during operation, and at the same time, it will also face challenges in the humid and hot environment under special climate conditions, such as rain, snow, high temperature, etc. Under extreme climate conditions, such as cold regions, tropical rainforest regions, etc., geotechnical structures may face challenges of heat and humidity and dynamic loading, which require structural materials to have corresponding adaptability and stability. In summary, engineering structures such as aerospace structures, railway track structures, and geotechnical structures in extreme environments face extreme environments such as heat and humidity and dynamic loading during service. Research shows that their component materials - aluminum alloys used in aerospace, sleeper wood used in railway tracks, and geotechnical materials, etc. are sensitive to temperature, humidity, and strain rate. Conducting mechanical property tests and behavior characterization of engineering materials under the coupled action of temperature, humidity, and high strain rate loads can more accurately simulate the loading environment and characterize the mechanical properties of materials in the real service environment, laying a foundation for establishing accurate extreme mechanics theories and numerical models of materials, predicting the extreme mechanical responses of materials, and the service performance of engineering structures. Improving the reliability and comparability of test results. However, the existing devices can only achieve a single or a combination of two functions and cannot achieve simultaneous loading of three functions. In many cases, the dynamic experimental device cannot be combined with the humid and hot coupling environment system. For example, Zhou Tao et al.'s Hopkinson pull rod device for combined static and dynamic loading in a high-temperature environment patents the development of a high strain rate test device, which only realizes the dynamic detection of concrete in a high-temperature environment. Because it is sensitive to air humidity and requires high sealing of the environmental system, and the movement of device components often occurs during dynamic experiments, resulting in poor sealing of the environmental system. Summary of the Invention

[0004] To solve the above technical problems, the present invention provides an experimental device for multi-scenario coupled loading of materials at high strain rates, which is used to detect the strain rate of a material specimen and includes: a power component for providing the power required for the coupled loading experiment; an environmental component for providing the environment required for the coupled loading experiment; a characterization component for applying stress to the material specimen, and the material specimen is arranged within the characterization component and the environmental component; an axial compression component for ensuring the normal operation of the characterization component in the axial direction; and a detection component for detecting impact data and then calculating the strain rate of the material specimen.

[0005] In a preferred embodiment of the present invention, the power component includes a cylinder, a launch chamber, an impact rod, and a launch chamber support; an intake valve and an exhaust valve are respectively arranged at the upper and lower ends of the cylinder, and an air chamber communicated with the intake valve and the exhaust valve is arranged within the cylinder; the output end of the air chamber is communicated with the launch chamber, the launch chamber is fixed on the launch chamber support, and one end of the impact rod is arranged within the launch chamber and is launched by the launch chamber.

[0006] In a preferred embodiment of the present invention, the characterization component includes an incident rod, an incident rod support, a transmission rod, a transmission rod support link, a hydraulic oil pump, and a damping device; the incident rod is fixed on the incident rod support, and one end of the incident rod is arranged within the environmental component; the transmission rod is fixed on the transmission rod support, one end of the transmission rod is arranged within the environmental component, and the other end abuts against the output end of the hydraulic oil pump; the material specimen is arranged between the incident rod and the transmission rod, and the damping device is arranged at one end of the hydraulic oil pump away from the output end for absorbing the excess energy generated during the experiment and preventing the generation of reflected compressive stress waves.

[0007] In a preferred embodiment of the present invention, the axial compression component includes a link, an incident rod end baffle, and a transmission rod end baffle; the link is arranged along the axial directions of the incident rod and the transmission rod, the incident rod end baffle is fixed at the other end of the incident rod and one end of the link; the transmission rod end baffle is fixed at the other end of the transmission rod and the other end of the link.

[0008] The present invention also provides a method for multi-scenario coupled loading experiment of materials at high strain rates, which uses the above experimental device for multi-scenario coupled loading of materials at high strain rates and includes the steps of: S1. Driving the impact rod to impact the incident rod by releasing compressed gas from the cylinder, and the incident rod and the transmission rod jointly generate a compressive dynamic load acting on the material specimen. At the same time, the damping device absorbs the excess energy generated during the experiment and prevents the generation of reflected compressive stress waves; S2. Based on the stress wave signals monitored during the test process, calculating the dynamic compressive strength, compressive strain, and compressive test strain rate of the material specimen under a preset static load value.

[0009] In a preferred embodiment of the present invention, before the step S1, the following steps are further included: erecting a high strain rate loading and performance characterization experimental device system: erecting an impact bar, an incident bar, a transmission bar and a damping device, carefully calibrating the incident bar and the impact bar using a laser calibrator to ensure the alignment of the bar system, and the alignment situation can be detected by the empty strike waveform signal after connecting the measurement system; pasting the material specimen: determining the pasting position of the material specimen, and the material specimen should be symmetrically pasted on both sides of the central axis of the bar; wiring and connecting the bridge: connecting the signal wire to the material specimen and then connecting it to the bridge box, and the connection method of the bridge box is a Wheatstone half-bridge connection; testing the signal situation of the material specimen to solve the interference; shaping the waveform: symmetrically pasting waveform shapers at the end of the incident bar close to the impact bar.

[0010] In a preferred embodiment of the present invention, the calculation formula of the strain rate in the step S2 is:

[0011] P1 = AE(ε i + ε r ) (1);

[0012] P2 = AEε t (2);

[0013]

[0014]

[0015] Wherein, A is the cross-sectional area of the incident bar and the transmission bar, A0 is the cross-sectional area of the material specimen, E is the elastic modulus of the incident bar and the transmission bar, C is the propagation speed of the wave in the incident bar and the transmission bar, L is the length of the incident bar, εi and εr are respectively the incident compressive stress wave and the reflected compressive stress wave signals monitored by the material specimen pasted on the incident bar, εt is the transmitted compressive stress wave signal monitored by the material specimen pasted on the transmission bar, P1 and P2 are the loads at both ends of the material specimen, σ(t), ε(t) and are respectively the dynamic compressive strength, strain and strain rate of the specimen varying with time.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] By setting up an axial compression system, the device of the present invention can apply a static compressive prestress load to the specimens for dynamic compression testing, simulate the compressive stress loads of wood, geotechnical materials, and magnesium alloys, and make the research tests on the dynamic compressive strength and failure characteristics of materials such as wood, geotechnical materials, and magnesium alloys closer to the actual usage environmental conditions of the materials, such as the low-temperature and high-humidity battlefield environment. Such an environment is very different from the environment where ordinary dynamic experimental devices in our country are located. Moreover, wooden baffles are often used on the inner side of the war chariot carriage, and wood products are sensitive to environmental humidity and temperature. Therefore, the mechanical properties obtained from the impact tests of wooden baffles in ordinary laboratories in our country are very different from the mechanical properties shown in the actual battlefield situation. However, this device can make the environment the same as the battlefield environment by adjusting the temperature and humidity inside the environmental system, thereby making the test results more reliable, and solving the technical problem that the existing devices cannot apply a static prestress compressive load during the dynamic compression test process.

[0018] By setting up a temperature and humidity loading system, temperature loads can be applied to specimens such as wood, geotechnical materials, and magnesium alloys in real time, simulate the influence of extreme environments on wood and rubber materials, make the tests on the dynamic compressive strength and failure laws of wood or rubber materials closer to the actual situation when they are used in extreme environments, and thus ensure that the test results are more accurate and reliable, making up for the defect that the existing devices can only carry out dynamic compression tests on specimens under normal environmental conditions. And the connection of the environmental system of this device to the incident bar and the transmission bar can maintain good airtightness of the environmental system when the incident bar and the transmission bar move. It is detected by the axial compression system that the friction force generated when the wooden plug is installed on the incident bar and the transmission bar is about 15 N, while the force applied to the incident bar and the transmission bar during the use of this device is more than 4000 N, making the influence of the wooden plug on the experiment negligible. By connecting the environmental system and the incident bar and the transmission bar through the wooden plug, this device can realize the dynamic detection of different materials under different humid and hot environments. Description of the Drawings

[0019] Figure 1 Shows the schematic diagram of the main structure of the high-strain-rate multi-scenario coupling loading experimental device for materials of the present invention;

[0020] Figure 2 Shown as Figure 1 The placement diagram of the material specimen in;

[0021] Figure 3 Shows the schematic diagram of the structure of the environmental component of the high-strain-rate multi-scenario coupling loading experimental device for materials of the present invention;

[0022] Figure 4 Shown as Figure 3 The side view of;

[0023] Figure 5 Shown as Figure 4 The top view of.

[0024] Description of component labels:

[0025] Intake valve 1, exhaust valve 2, air chamber 3, emission chamber 4, emission chamber support 5, impact rod 6, incident rod support 7, incident rod end baffle 8, incident rod 9, environmental chamber 10, transmission rod 11, transmission rod support 12, transmission rod end baffle 13, hydraulic oil pump 14, damping device 15, connecting rod 16, specimen 17. Specific implementation mode

[0026] Next, in combination with the accompanying drawings and specific implementation modes, the present invention will be further described.

[0027] Please refer to Figures 1 to 5 As shown. A high strain rate multi-scenario coupling loading experimental device for materials provided in this embodiment is used to detect the strain rate of a material specimen, and includes: a power component for providing the power required for the coupling loading experiment; an environmental component for providing the environment required for the coupling loading experiment; a characterization component for applying stress to the material specimen, and the material specimen is arranged in the characterization component and the environmental component; an axial compression component for ensuring the normal operation of the characterization component in the axial direction; a detection component for detecting impact data and then calculating the strain rate of the material specimen. Further, the power component includes a cylinder, an emission chamber, an impact rod and an emission chamber support; an intake valve and an exhaust valve are respectively arranged at the upper and lower ends of the cylinder, and an air chamber communicated with the intake valve and the exhaust valve is arranged in the cylinder;

[0028] The output end of the air cavity is communicated with the emission cavity. The emission cavity is fixed on the emission cavity support. One end of the impact rod is arranged in the emission cavity and is emitted by the emission cavity. The characterization assembly includes an incident rod, an incident rod support, a transmission rod, a transmission rod support connecting rod, a hydraulic oil pump and a damping device. The incident rod is fixed on the incident rod support, and one end of the incident rod is arranged in the environment assembly. The transmission rod is fixed on the transmission rod support, and one end of the transmission rod is arranged in the environment assembly, and the other end abuts against the output end of the hydraulic oil pump. The material specimen is arranged between the incident rod and the transmission rod. The damping device is arranged at one end of the hydraulic oil pump away from the output end and is used for absorbing the excess energy generated in the test and preventing the generation of reflected compressive stress waves. The axial compression assembly includes a connecting rod, an incident rod end baffle and a transmission rod end baffle. The connecting rod is arranged along the axial directions of the incident rod and the transmission rod. The incident rod end baffle is fixed at the other end of the incident rod and one end of the connecting rod. The transmission rod end baffle is fixed at the other end of the transmission rod and the other end of the connecting rod. The ends of the incident rod and the transmission rod are arranged inside the environmental chamber. The connecting holes through which the incident rod and the transmission rod pass. The environmental chamber is composed of a moisture-proof and heat-insulating frame, a heater, a humidity sensor and a humidity control system, etc. The heater is set to heat the liquid water to water vapor through the humidity control system to reach the required experimental humidity, and the heater heats the heating furnace. The humidity sensor is used for monitoring the humidity inside the environmental chamber and feeding back the humidity information to the humidity control system, and the moisture-proof and heat-insulating frame is used for isolating the influence of the external environment.

[0029] The present invention also provides a method for a multi-scenario coupled loading experiment of a material at a high strain rate. By using the above-mentioned experimental device for a multi-scenario coupled loading experiment of a material at a high strain rate, the method includes the steps: S1. Driving the impact rod to impact the incident rod by releasing compressed gas through a cylinder. The incident rod and the transmission rod jointly generate a compressive dynamic load acting on the material specimen. At the same time, the damping device absorbs the excess energy generated in the test and prevents the generation of reflected compressive stress waves. S2. Calculating the dynamic compressive strength, compressive strain and compressive test strain rate of the material specimen under a preset static load value based on the stress wave signals monitored during the test process. Before the step S1, there is also a step:

[0030] Setting up the high strain rate loading and performance characterization experimental device system: Setting up the impact rod, the incident rod, the transmission rod and the damping device. Carefully calibrating the incident rod and the impact rod using a laser calibrator to ensure the alignment of the rod system. After connecting the measurement system, the alignment situation can be detected by the empty-shot waveform signal. If the alignment situation between the incident rod and the transmission rod is good, the reflected wave can hardly be seen, and this alignment situation is acceptable.

[0031] Pasting material specimen: Determine the pasting positions of the material specimen, and the material specimen should be symmetrically pasted on both sides of the central axis of the rod; determine the pasting positions of the strain gauges, and the strain gauges should be symmetrically pasted on both sides of the central axis of the rod; use an alcohol cotton ball to carefully wipe the positions where the strain gauges need to be pasted; if the rod is not smooth enough, it needs to be polished with sandpaper in advance and then wiped clean with alcohol; after waiting for the alcohol to evaporate completely, apply an appropriate amount of 502 glue on the strain gauge and paste the strain gauge (note: do not let the metal wire of the strain gauge contact the rod to avoid short circuit).

[0032] Wiring and connecting the Wheatstone bridge: Connect the signal wire to the material specimen and then connect it to the bridge box. The connection method of the bridge box is the Wheatstone half-bridge connection; Connect the signal amplifier and oscilloscope: Connect the bridge box with the strain gauges attached to the input signal of the strain amplifier, and then connect the output signal to the oscilloscope to display the signal recorded by the strain gauges. Test the signal condition of the material specimen and solve the interference; The signal of the strain gauge may encounter interference, such as spikes and noise. If the signal interference exceeds 5% range, the signal can be considered not clean enough and needs to be processed. The processing methods include: checking the tightness of the wiring, adding a ground wire, adding a shield wire outside the signal wire, using twisted pair, etc. Turn on the hydraulic oil pump of the axial compression system and adjust the axial compression device to the required predetermined static load value. This value can be assigned according to the measured in-situ stress value or set as a certain percentage value of the static uniaxial compressive strength of the specimen. Waveform shaping: Symmetrically paste waveform shapers at the end of the incident bar close to the impact bar. Symmetrically paste waveform shapers (copper sheets with a diameter of 8 mm and a thickness of 1 mm) at the end of the incident bar 5 close to the impact bar.

[0033] Among them, the calculation formula for the strain rate in step S2 is: P1 = AE(ε i +ε r )(1); P2 = AEε t (2); Among them, A is the cross-sectional area of the incident bar and the transmission bar, A0 is the cross-sectional area of the material specimen, E is the elastic modulus of the incident bar and the transmission bar, C is the wave propagation speed in the incident bar and the transmission bar, L is the length of the incident bar, εi and εr are the incident compressive stress wave and reflected compressive stress wave signals monitored by the material specimen pasted on the incident bar respectively, εt is the transmitted compressive stress wave signal monitored by the material specimen pasted on the transmission bar, P1 and P2 are the loads at both ends of the material specimen, σ(t), ε(t) and are the dynamic compressive strength, strain and strain rate of the specimen varying with time respectively.

[0034] By setting up an axial compression system, the device of the present invention can apply a static compression prestress load to the specimens for dynamic compression testing, simulate the compression stress loads of wood, geotechnical materials, and magnesium alloys, and make the research and testing of the dynamic compression strength and failure characteristics of materials such as wood, geotechnical materials, and magnesium alloys closer to the actual usage environmental conditions of the materials, such as the low temperature and high humidity in the battlefield environment. Such an environment is very different from the environment where ordinary dynamic experimental devices in our country are located. Wooden baffles are often used on the inner side of the combat vehicle compartment, and wood products are sensitive to environmental humidity and temperature. Therefore, the mechanical properties obtained from the impact experiments of wooden baffles in ordinary laboratories in our country are very different from the mechanical properties shown in the actual battlefield situation. However, this device can make the environment the same as the battlefield environment by adjusting the temperature and humidity inside the environmental system, thereby making the test results more reliable, and solving the technical problem that the existing devices cannot apply a static prestress compression load during the dynamic compression testing process.

[0035] By setting up a temperature and humidity loading system, temperature loads can be applied to specimens such as wood, geotechnical materials, and magnesium alloys in real time, simulate the influence of extreme environments on wood and rubber materials, make the testing of the dynamic compression strength and failure laws of wood or rubber materials closer to the actual situation when they are used in extreme environments, and thus ensure that the test results are more accurate and reliable, making up for the defect that the existing devices can only carry out dynamic compression testing of specimens under normal environmental conditions. The environmental system of this device is connected to the incident bar and the transmission bar, so that the environmental system can maintain good sealing performance when the incident bar and the transmission bar move. It is detected by the axial compression system that the friction force generated when the wooden plug is installed on the incident bar and the transmission bar is about 15 N, while the force applied to the incident bar and the transmission bar during the use of this device is more than 4000 N, making the influence of the wooden plug on the experiment negligible. By connecting the environmental system to the incident bar and the transmission bar through the wooden plug, this device can achieve dynamic detection of different materials under different humid and hot environments.

[0036] The above embodiments are only the preferred embodiments of the present invention and cannot be used to limit the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention belong to the scope of protection required by the present invention.

Claims

1. An experimental device for multi-scenario coupled loading of materials at high strain rates, which is used to detect the strain rate of material specimens, is characterized in that Comprising: A power component for providing the power required for the coupled loading experiment; An environment component for providing the environment required for the coupled loading experiment; A characterization component for applying stress to the material specimen, the material specimen being disposed within the characterization component and the environment component; An axial compression component for ensuring the normal operation of the characterization component in the axial direction; A detection component for detecting impact data and calculating the strain rate of the material specimen.

2. The experimental device for multi-scenario coupled loading of materials at high strain rates according to claim 1, characterized in that, The power component includes a cylinder, a launch chamber, an impact rod, and a launch chamber support; An air inlet valve and an air release valve are respectively disposed at the upper and lower ends of the cylinder, and an air chamber communicating with the air inlet valve and the air release valve is disposed within the cylinder; The output end of the air chamber communicates with the launch chamber, the launch chamber is fixed on the launch chamber support, and one end of the impact rod is disposed within the launch chamber and is launched by the launch chamber.

3. The experimental device for multi-scenario coupled loading of materials at high strain rates according to claim 2, characterized in that, The characterization component includes an incident rod, an incident rod support, a transmission rod, a transmission rod support link, a hydraulic oil pump, and a damping device; The incident rod is fixed on the incident rod support, and one end of the incident rod is disposed within the environment component; the transmission rod is fixed on the transmission rod support, one end of the transmission rod is disposed within the environment component, and the other end abuts against the output end of the hydraulic oil pump; the material specimen is disposed between the incident rod and the transmission rod, and the damping device is disposed at one end of the hydraulic oil pump away from the output end for absorbing the excess energy generated during the test and preventing the generation of reflected compressive stress waves.

4. The experimental device for multi-scenario coupled loading of materials at high strain rates according to claim 3, wherein The axial compression component includes a link, an incident rod end baffle, and a transmission rod end baffle; The link is disposed along the axial directions of the incident rod and the transmission rod, the incident rod end baffle is fixed at the other end of the incident rod and one end of the link; the transmission rod end baffle is fixed at the other end of the transmission rod and the other end of the link.

5. An experimental method for multi-scenario coupled loading of materials at high strain rates, using the experimental device for multi-scenario coupled loading of materials at high strain rates described in any one of claims 1-4, characterized in that, Including steps: S1. Driving the impact rod to impact the incident rod by releasing compressed gas from the cylinder, the incident rod and the transmission rod jointly generating a compressive dynamic load acting on the material specimen. Meanwhile, the damping device absorbs the excess energy generated during the test and prevents the generation of reflected compressive stress waves; S2. Calculating the dynamic compressive strength, compressive strain, and compressive test strain rate of the material specimen under a preset static load value based on the stress wave signals monitored during the test process.

6. The experimental method for multi-scenario coupled loading of materials at high strain rates according to claim 5, characterized in that, Before the step S1, there are also steps: Setting up the high strain rate loading and performance characterization experimental device system: setting up the impact rod, incident rod, transmission rod, and damping device, carefully calibrating the incident rod and the impact rod using a laser calibrator to ensure the alignment of the rod system, and the alignment situation can be detected by the empty firing waveform signal after connecting the measurement system; Pasting the material specimen: determining the pasting position of the material specimen, and the material specimen should be symmetrically pasted on both sides of the central axis of the rod; Connecting wires and a bridge: connecting the signal wires to the material specimen and then connecting them to the bridge box, and the connection method of the bridge box is a Wheatstone half-bridge connection; Testing the signal situation of the material specimen and solving interference; Shaping the waveform: symmetrically pasting waveform shapers at the end of the incident rod close to the impact rod.

7. The experimental method for multi-scenario coupled loading of materials at high strain rates according to claim 6, characterized in that, The calculation formula for the strain rate in the step S2 is: P1 = AE(ε i + ε r )(1); P2 = AEε t (2); Among them, A is the cross-sectional area of the incident bar and the transmission bar, A0 is the cross-sectional area of the material specimen, E is the elastic modulus of the incident bar and the transmission bar, C is the propagation speed of the wave in the incident bar and the transmission bar, L is the length of the incident bar, εi and εr are the incident compressive stress wave and the reflected compressive stress wave signals monitored by the material specimen pasted on the incident bar respectively, εt is the transmitted compressive stress wave signal monitored by the material specimen pasted on the transmission bar, P1 and P2 are the loads at both ends of the material specimen, and σ(t), ε(t) and are the dynamic compressive strength, strain and strain rate of the specimen varying with time respectively.

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