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CN-115824785-B - System and method for measuring energy release rate of movement crack under explosive load

CN115824785BCN 115824785 BCN115824785 BCN 115824785BCN-115824785-B

Abstract

The invention relates to a system and a method for measuring the energy release rate of a motion crack under an explosion load, belonging to the field of explosion dynamics, wherein the system comprises: the method comprises the steps of a cold light source, a speckle target surface, an electric translation table, a test piece, a clamp, an explosive package, a multichannel time sequence delay controller, a pulse igniter, a high-speed camera, a camera support and a computer, wherein a digital gradient sensitive light measurement technology and an explosion dynamics measurement technology are combined, the speckle target surface at the rear of the organic glass sheet test piece under the explosion load is shot by the high-speed camera, and a light deflection angle distribution field near the moving crack tip of the organic glass sheet is measured by the digital gradient sensitive technology, so that the dynamic energy release rate of the moving crack is measured, the complicated process of a digital photoelastic stripe stage number is omitted, the experimental steps are simple and convenient, the crack tip is easier to identify, the experimental result is reliable, and compared with the traditional method, the crack expansion speed correction coefficient is added, and the experimental result is more accurate.

Inventors

  • LIU WEI
  • CHENG WEIXIAN
  • ZHANG ZHIQIAN
  • YUE ZHONGWEN
  • YANG LIYUN
  • ZHANG XIAOFEI
  • WANG YANBING
  • CHENG JIAN

Assignees

  • 中国矿业大学(北京)

Dates

Publication Date
20260505
Application Date
20230109

Claims (8)

  1. 1. A system for measuring the energy release rate of a moving crack under an explosive load, the system comprising: a speckle target surface (4); A cold light source (2) for emitting light, which irradiates the speckle target surface (4); a translation stage (6); A test piece (9); A clamp (7) movably arranged on the translation stage (6), and the clamp (7) is used for fixing the test piece (9); an explosive package (8) fixed on the test piece (9); A pulse igniter (11) connected with the explosive package (8); A high-speed camera (14) for photographing the speckle target surface (4); A multi-channel time sequence delay controller (10) connected with the pulse igniter (11) and the high-speed camera (14) and used for sending trigger signals to the pulse igniter (11) and the high-speed camera (14); The computer (16) is connected with the translation table (6) and the high-speed camera (14) and is used for calculating the energy release rate of the movement crack under the explosive load; The calculation formula of the energy release rate of the motion crack under the explosion load is as follows: ; Wherein, the To move the energy release rate of the crack under explosive load, For the total number of moving cracks caused by explosive loads, Is the elastic modulus of the organic glass test piece, Is the first Strip motion crack extension line The included angle between the directions is that, And For the crack growth rate correction factor, And Respectively the points to be measured are on the speckle target surface Direction and direction A directional light deflection angle; The crack growth rate correction coefficient And The expression of (2) is as follows: , ; , ; Wherein, the And The thickness and the elastic optical constant of the organic glass plate test piece are respectively, And For the density and poisson's ratio of the plexiglass sheet material, Is the first The propagation speed of the strip motion crack, And Is the first to Strip crack propagation speed Related dynamic coefficients.
  2. 2. The measuring system of the energy release rate of the movement cracks under the explosion load according to claim 1, wherein the test piece (9) is a plexiglass plate with a central blast hole, and the explosive cartridge (8) is arranged in the central blast hole of the plexiglass plate test piece.
  3. 3. The system for measuring the rate of energy release from a moving crack under an explosive load according to claim 1, further comprising: a light source bracket (3), a target surface support (5) and a camera bracket (15); The cold light source (2), the speckle target surface (4) and the high-speed camera (14) are sequentially fixed on the light source bracket (3), the target surface support (5) and the camera bracket (15).
  4. 4. The system for measuring the energy release rate of a moving crack under an explosive load according to claim 1, wherein the translation stage (6) is an electric translation stage, and the clamp (7) moves up and down and left and right in the electric translation stage (6).
  5. 5. The system for measuring the rate of energy release from a moving crack under an explosive load according to claim 1, further comprising: a direct current power supply (1) and the cold light source (2) are used for supplying power to the cold light source (2); a signal line (12) connected to the pulse igniter (11); and one end of the enameled wire (13) is connected with the signal wire (12), and the other end of the enameled wire is connected with the explosive package (8).
  6. 6. The system for measuring the energy release rate of a moving crack under an explosive load according to claim 1, wherein the cold light source (2) comprises a first cold light source and a second cold light source.
  7. 7. The system for measuring the energy release rate of a moving crack under explosive load according to claim 1, wherein the center of the speckle target surface (4), the center of the test piece (9) and the lens of the high-speed camera (14) are positioned on the same main optical axis.
  8. 8. A method for measuring the energy release rate of a moving crack under an explosive load, wherein the measuring method is applied to the measuring system according to any one of claims 1 to 7, and the measuring method comprises: Spraying paint spots with black and white phases on the surface of the speckle target surface (4); fixing a test piece (9) on a clamp (7) so that the surface of the test piece (9) is parallel to the speckle target surface (4); Charging and connecting the test piece (9); Turning on a direct current power supply (1) to illuminate the surface of a speckle target surface (4) by a cold light source (2); Adjusting an experimental system light path, and aligning a lens of a high-speed camera (14) to a speckle target surface behind the test piece (9); adjusting the position and focal length of a lens of a high-speed camera (14) to enable paint spots on the speckle target surface (4) to form clear images in the middle of the high-speed camera (14) at all times; The multichannel time sequence delay controller (10) sends out trigger signals, one path of the trigger signals is transmitted to the pulse igniter (11), and the other path of trigger signals is connected to the high-speed camera (14) to control the time sequence synchronization of the pulse igniter (11) and the high-speed camera (14); The pulse igniter (11) generates instantaneous high voltage to cause explosive detonation after receiving an external trigger signal, and the high-speed camera (14) continuously takes pictures after receiving the external trigger signal; After explosive detonation, single or multiple cracks are initiated and expanded in the organic glass plate test piece, the light deflection displacement fields on the speckle target surface near the tip of the moving crack at different moments are calculated by a computer, and then the light deflection angles in the X direction and the Y direction are obtained by a digital gradient sensitive light measurement technology; and calculating the energy release rate of the moving crack under the explosion load according to the light deflection angle information of the to-be-detected point on the crack extension line.

Description

System and method for measuring energy release rate of movement crack under explosive load Technical Field The invention relates to the field of explosion dynamics, in particular to a system and a method for measuring the energy release rate of a motion crack under an explosion load. Background With the remarkable increase of special working conditions with high explosion risks in various industries, the service environments of some key bearing structures are more and more complicated. The internal crack propagation characteristic and dynamic failure mechanism of the structure under the explosive load are important scientific bases for predicting the residual strength of the structure and evaluating the safety of the structure. At present, strain electrical measurement technology, photoelastic method, digital speckle correlation, caustic wire and other optical measurement technologies are mainly used for measuring crack tip fracture parameters under explosive load. The strain electrical measurement technology needs to be stuck with a strain gauge each time, the testing steps are complex, the testing result is influenced by the sticking precision of the strain gauge, the photoelastic method needs to count the number of fringe orders each time, the working procedure is complex, the identification precision of the optical measurement technology such as digital speckle correlation, caustic wires and the like to the crack tip is low, and the crack expansion speed testing precision is influenced. The digital gradient sensitivity technology is a novel optical measurement technology based on analysis of light deflection angles near a stress singular field, so that crack tip strain gradient field and fracture parameter information are obtained. It is highly desirable to develop a system and method that combines digital gradient sensitive optical measurement technology with explosion dynamics measurement technology to more conveniently detect the fracture parameters of a moving crack under an explosion load. Disclosure of Invention The invention aims to provide a system and a method for measuring the energy release rate of a motion crack under explosive load, which can accurately measure the energy release rate of a single or multiple explosion-generated motion cracks at different moments by combining a digital gradient sensitive optical measurement technology and an explosion dynamics test technology. In order to achieve the above object, the present invention provides the following solutions: A measurement system for motion crack energy release rate under explosive load, the measurement system comprising: a speckle target surface 4; a cold light source 2 for emitting light source, which irradiates on the speckle target surface 4; A translation stage 6; A test piece 9; a clamp 7 movably disposed on the translation stage 6, and the clamp 7 is used for fixing the test piece 9; An explosive package 8 fixed on the test piece 9; a pulse igniter 11 connected to the explosive cartridge 8; a high-speed camera 14 for photographing the speckle target surface 4; a multi-channel time sequence delay controller 10 connected with the pulse igniter 11 and the high-speed camera 14 and used for sending trigger signals to the pulse igniter 11 and the high-speed camera 14; and the computer 16 is connected with the translation stage 6 and the high-speed camera 14 and is used for calculating the energy release rate of the movement crack under the explosive load. Optionally, the test piece 9 is an organic glass plate with a central blast hole, and the explosive cartridge 8 is arranged in the central blast hole of the organic glass plate test piece. Optionally, the measurement system further comprises: A light source holder 3, a target surface holder 5, and a camera holder 15; the cold light source 2, the speckle target surface 4 and the high-speed camera 14 are sequentially fixed on the light source bracket 3, the target surface support 5 and the camera bracket 15. Optionally, the translation stage 6 is an electric translation stage, and the clamp 7 moves up and down and left and right in the electric translation stage 6. Optionally, the measurement system further comprises: The direct current power supply 1 is connected with the cold light source 2 and is used for supplying power to the cold light source 2; a signal line 12 connected to the pulse igniter 11; And one end of the enameled wire 13 is connected with the signal wire 11, and the other end of the enameled wire is connected with the explosive package 8. Optionally, the cold light source 2 comprises a first cold light source and a second cold light source. Optionally, the center of the speckle target surface 4, the center of the test piece 9 and the lens of the high-speed camera 14 are located on the same main optical axis. Based on the system in the invention, the invention further provides a measuring method of the energy release rate of the movement crack under the explosive lo