CN-122016514-A - Dynamic shear deformation freezing and measuring system and method for single-pulse torsion bar

CN122016514ACN 122016514 ACN122016514 ACN 122016514ACN-122016514-A

Abstract

The invention relates to the technical field of dynamic mechanical testing, in particular to a system and a method for freezing and measuring dynamic shear deformation of a single-pulse torsion bar. The torsion bar system comprises an incident bar and a transmission bar, is used for transmitting torsional stress waves and clamping a thin-wall tubular sample, and the single pulse loading mechanism absorbs reflected wave energy through the cooperation of the wave unloading bar and the one-way coupler, so that single pulse loading is realized and secondary loading is avoided. According to the invention, the movable buckle is arranged on the incident rod and used for accurately adjusting the loading pulse width, the unidirectional coupler and the wave unloading rod on the incident rod and the transmission rod are matched, the single pulse loading control is realized, the loaded form of the sample is frozen, the thermal-force coupling data in the loading process are synchronously obtained by utilizing the infrared transient temperature measurement detector and the strain gauge, and a high-precision experimental means is provided for deeply researching the shear band formation, the damage evolution and the thermoplastic instability mechanism of the material under the high strain rate shear load.

Inventors

DAI LANHONG
WANG DERU
SU MINGYAO
LI TONG
CHEN YAN
WANG HAIYING

Assignees

中国科学院力学研究所

Dates

Publication Date: 20260512
Application Date: 20260122

Claims (10)

1. A dynamic shear deformation freeze and measurement system for a single pulse torsion bar, comprising: A torsion bar system comprising an incident bar (2) and a transmission bar (3) arranged in sequence along the same axis for applying a dynamic torsion load to a specimen (13) clamped therebetween; The single pulse loading mechanism comprises a loading end (5) arranged on the incidence rod (2) and a wave unloading rod (1) arranged at one end of the incidence rod (2) and one end of the transmission rod (3) far away from the sample (13), wherein the incidence rod (2) and the transmission rod (3) are connected with the wave unloading rod (1) through a one-way coupler (4), and the one-way coupler (4) is configured to transmit torsion load in a loading stage and allow relative sliding between the torsion rod and the wave unloading rod after stress waves pass so as to block reflected waves from returning into the loading incidence rod (2) and the transmission rod (3); The measuring system comprises an infrared transient temperature measuring detector (9) and a strain gauge arranged on the incidence rod (2) and the transmission rod (3), and acquires the temperature of the sample (13) in real time through the infrared transient temperature measuring detector (9) and acquires the shear strain of the incidence rod (2) and the transmission rod (3) in real time through the strain gauge; When the loading end (5) instantly releases the loading torque of the incident rod (2), the wave unloading rod (1) absorbs reflected wave energy so as to freeze the deformation morphology after the single torsion pulse is applied to the sample (13), and simultaneously, the measurement system synchronously acquires strain, stress and temperature data through the strain flower and the infrared transient temperature measurement detector (9) to form thermal-force coupling information, and provides data for the formation, damage evolution and destabilization mechanism of a shear band of a material under high strain rate shear load; And the specimen (13) is of a thin-walled tubular structure such that its gauge region is in an approximately simple shear strain state during torsion.
2. A dynamic shear deformation freezing and measuring system of a monopulse torsion bar according to claim 1, wherein, A movable buckle (6) is arranged on the incidence rod (2), the loading end (5) is far away from the sample (13), and the movable buckle (6) is arranged between the loading end (5) and the sample (13); The movable clasp (6) is configured to be movable and lockable between the loading end (5) and the thin-walled tubular specimen (13) to adjust a torque storage area length of the incident rod (2) between the loading end (5) and the movable clasp (6), controlling a loading pulse width and a target shear strain; And the movable buckle (6) is configured to be instantly released to trigger the torque stored in the torque energy storage area to form a single torsion pulse wave.
3. A dynamic shear deformation freezing and measuring system of a monopulse torsion bar according to claim 1, wherein, The wall thickness and the outer diameter of the sample (13) satisfy the following conditions: ; Wherein, the Is the wall thickness of the steel sheet, Is the outer diameter.
4. A dynamic shear deformation freezing and measuring system of a monopulse torsion bar according to claim 1, wherein, The unidirectional coupler (4) comprises a transition structure sleeved on the end part of the incident rod (2), the end part of the transmission rod (3) and the end part of the wave unloading rod (1), and the transition structure comprises a positive connection part (16), a negative connection part (17) and a sliding block (18); the positive connection part (16) is configured to allow a torsional wave in a preset direction to be completely transmitted, and when a reflected wave in the opposite direction is transmitted to the negative connection part (17), the sliding block (18) is driven to move so as to disconnect the positive connection part (16) from the negative connection part (17), and the reflected wave is isolated in the wave unloading rod (1).
5. A dynamic shear deformation freezing and measuring system of a monopulse torsion bar according to claim 1, wherein, A first strain gauge (14) is arranged on the incidence rod (2) in the area between the movable buckle (6) and the sample (13) and/or the transmission rod (3) and is used for connecting a dynamic strain gauge to measure incident wave and transmitted wave signals; a second strain gauge (15) is arranged on a torque energy storage area of the incidence rod (2) between the loading end (5) and the movable buckle (6) and is used for connecting a static strain gauge to measure the pre-loading torque; The magnitude of the incident torsional wave and the loading strain rate of the test sample (13) are controlled by measuring and adjusting the magnitude of the pre-loading torque.
6. A dynamic shear deformation freezing and measuring system for a monopulse torsion bar according to claim 2, wherein, The movable buckle (6) comprises a chuck (19) sleeved on the incidence rod (2), a snap-off bolt (20) and a fastening nut (21) which are used for locking the chuck (19) at a designated position of the incidence rod (2); And a graduation scale is arranged on the adjacent supporting frame of the incidence rod (2) and used for calibrating the axial position of the movable buckle.
7. A dynamic shear deformation freezing and measuring system of a monopulse torsion bar according to claim 4, wherein, The measurement system further includes: The dynamic data acquisition system is connected with the first strain flower (14) through a dynamic strain gauge and is used for acquiring and processing torsional load waveform data in real time; And the static data acquisition system is connected with the second strain gauge (15) through a static strain gauge and is used for measuring a preset shear strain rate.
8. A dynamic shear deformation freezing and measuring system of a monopulse torsion bar according to claim 7, The measuring system further comprises a parabolic mirror (8), wherein the parabolic mirror (8) is used for focusing infrared radiation on the surface of the sample (13) to the infrared transient temperature measurement detector (9), and the infrared transient temperature measurement detector (9) is arranged facing the surface of the sample (13); The infrared transient temperature measurement detector (9) is triggered synchronously with the dynamic data acquisition system and is used for synchronously recording the temperature rise of the surface of the sample (13) in the single pulse loading process.
9. A method of using a dynamic shear deformation freeze and measurement system of a single pulse torsion bar according to any one of claims 2 to 8, comprising the steps of: Step 100, mounting a thin-wall tubular sample between an incident rod and a transmission rod, calculating a required loading pulse width according to a target shear strain, and correspondingly adjusting and locking the axial position of a movable buckle on the incident rod; Step 200, applying a pre-torque through a loading end, storing the pre-torque in an incident rod section between the loading end and a movable buckle, triggering the movable buckle to release instantaneously, generating a single torsion pulse wave to load a sample, and synchronously collecting torsion load waveform data and transient temperature data on the surface of the sample, wherein after the stress wave is transmitted into a wave unloading rod through a one-way coupler, reflected waves are isolated, and the sample is frozen in a deformation state under a target shear strain; And 300, carrying out microstructure characterization on the deformed and frozen sample, and carrying out correlation analysis on a characterization result and synchronously acquired mechanical and temperature data.
10. The method for precisely freezing and synchronously measuring temperature by dynamic shear deformation according to claim 9, wherein, In step 100, the formula for determining and adjusting the torque pulse width is: ; Wherein, the In order to load the pulse width, For the distance between the movable catch and the loading end, Is the torsional wave velocity of the rod.

Description

Dynamic shear deformation freezing and measuring system and method for single-pulse torsion bar Technical Field The invention relates to the technical field of dynamic mechanical testing, in particular to a system and a method for freezing and measuring dynamic shear deformation of a single-pulse torsion bar. Background The Hopkinson torsion bar is a key experimental device for researching the shearing mechanical behavior of engineering materials such as metal, composite materials, ceramics and the like under high strain rate. The torsion bar system applies dynamic torsion load to the sample, so that the dynamic shear stress-strain relation, strain rate sensitivity and shear failure characteristics of the material can be obtained, and important data support is provided for material design and safety evaluation under the dynamic load working conditions of impact, penetration, explosion and the like. However, in the conventional hopkinson torsion bar system, the torsional wave is transmitted back and forth on the rod until the consumption is finished, so that the stress wave returns to the sample after being reflected at the end of the rod, and the sample is subjected to multiple loading, so that the final deformation state becomes a multiple loading accumulation result, a clear corresponding relation is difficult to establish with a specific loading process, transient temperature measurement capability strictly synchronous with a dynamic loading process is lacking, and reliable thermal-force coupling evolution data is difficult to acquire. Therefore, the conventional hopkinson torsion bar system has difficulty in suppressing stress waves reciprocally transmitted in the rod member to cause that the sample is loaded for a plurality of times to generate an accumulated form, and has difficulty in establishing a clear corresponding relation with a specific loading process and performing thermal measurement on the loading of the sample, so that the deformation of the sample is difficult to be matched with thermal information in the loading process. Disclosure of Invention The invention aims to provide a dynamic shear deformation freezing and measuring system and method for a single-pulse torsion bar, which are used for solving the technical problems that in the prior art, a sample is difficult to load repeatedly to generate an accumulated form due to the fact that stress waves transmitted in a rod piece in a reciprocating manner are difficult to be restrained, a clear corresponding relation is difficult to be established with a specific loading process, and thermal measurement is difficult to be carried out on the loading of the sample, so that the deformation of the sample is difficult to be matched with thermal information in the loading process. In order to solve the technical problems, the invention specifically provides the following technical scheme: A dynamic shear deformation freeze and measurement system for a single pulse torsion bar, comprising: A torsion bar system including an incident bar and a transmission bar disposed in order along the same axis for applying a dynamic torsion load to a specimen clamped therebetween; A single pulse loading mechanism comprising a loading end arranged on the incidence rod and a wave unloading rod arranged on one end of the incidence rod and the transmission rod, which is far away from the sample, wherein the incidence rod and the transmission rod are connected with the wave unloading rod through a one-way coupler, the one-way coupler is configured to transmit torsion load in a loading stage and allow relative sliding between the torsion rod and the wave unloading rod after the stress wave passes so as to block reflected waves from returning to the loading incidence rod 2 and the transmission rod 3; The measuring system comprises an infrared transient temperature measuring detector and a strain gauge arranged on the incident rod and the transmission rod, and is used for collecting the temperature of the sample in real time through the infrared transient temperature measuring detector and collecting the shear strain of the incident rod and the transmission rod in real time through the strain gauge; When the loading end instantly releases the loading torque of the incident rod, the wave unloading rod absorbs reflected wave energy so as to freeze the deformation morphology after the single torsion pulse is applied to the sample, and simultaneously, the measurement system synchronously collects strain, stress and temperature data through the strain flower and the infrared transient temperature measurement detector to form thermal-force coupling information and provide data for the formation, damage evolution and instability mechanism of a shear band of the material under high strain rate shear load; And the sample is of a thin-walled tubular structure so that its gauge region is in an approximately simple shear strain state during torsion. As a preferable mode of the pres