CN-122016460-A - Acoustic emission and high-speed imaging synchronous monitoring system and method for fracture test

CN122016460ACN 122016460 ACN122016460 ACN 122016460ACN-122016460-A

Abstract

The invention provides a synchronous monitoring system and a synchronous monitoring method for acoustic emission and high-speed imaging of a fracture test, and belongs to the technical field of material fracture test monitoring. The monitoring system comprises a loading test device, an acoustic emission monitoring device, a high-speed imaging device and a synchronous control system, wherein the synchronous control system collects a load signal output by a loading sensor, generates a synchronous pulse when the load reaches a peak value through a peak value detection algorithm, and simultaneously records and triggers a high-speed camera by the acoustic emission system, so that a unified time reference is established, and accurate alignment of acoustic emission data and high-speed image data is realized. The system has simple structure and high synchronization precision, and can stably capture the rapid crack initiation and propagation process near the fracture peak value.

Inventors

WU SHAN
WU LIHUI
ZHA FUSHENG
HAN HEMING
WANG QIAO
Pang Yixiao
LI TIANGUO

Assignees

合肥工业大学

Dates

Publication Date: 20260512
Application Date: 20260306

Claims (5)

1. The synchronous monitoring system for the acoustic emission and high-speed imaging of the fracture test is used for monitoring the fracture state of a rock sample (5) and is characterized by comprising a loading test device (1), an acoustic emission monitoring device (3), a high-speed imaging device (4), a synchronous control system (6) and a computer (8), wherein the rock sample (5) is arranged in the loading test device (1) and is provided with at least one loading sensor (2), and the acoustic emission monitoring device (3) comprises an acoustic emission sensor (31) and an acoustic emission acquisition instrument (32); The synchronous control system (6) comprises a signal conditioning module (61), an analog-digital conversion module (62), a control module (63) and a digital-analog conversion module (64) which are electrically connected in sequence and unidirectionally, wherein the signal conditioning module (61) is electrically connected with the loading sensor (2) and is used for receiving and conditioning load signals of the loading sensor (2), the analog-digital conversion module (62) is used for collecting the conditioned load signals and transmitting the conditioned load signals to the controller (63), the control module (63) is internally provided with a peak detection algorithm and is used for continuously monitoring the load signals and outputting a trigger command when the load signals reach a peak value, and the digital-analog conversion module (64) is used for generating a synchronous pulse (7) after receiving the trigger command and simultaneously transmitting the synchronous pulse (7) to the acoustic emission collector (32) and the high-speed imaging device (4) through the electrical connection; The acoustic emission sensor (31) is used for collecting acoustic emission signals generated by the rock sample (5) in the loading test process, the acoustic emission collector (32) is used for receiving and recording the synchronous pulse (7), establishing a time reference and realizing time alignment of acoustic emission data and high-speed image data, and the high-speed imaging device (4) is used for collecting the image data of the rock sample (5) in the loading test process by taking the synchronous pulse (7) as a trigger signal.
2. The synchronous monitoring system for fracture test acoustic emission and high-speed imaging according to claim 1, wherein the high-speed imaging device (4) comprises a high-speed camera and a light supplementing device, the acquisition frame rate of the high-speed camera is not less than 50000 frames/second, the acquisition resolution is preferably 256×232 pixels, and the light supplementing device comprises at least two high-brightness LED light supplementing lamps for forming uniform illumination on the surface of a rock sample (5).
3. The synchronous monitoring system for fracture test acoustic emission and high-speed imaging according to claim 1, wherein the analog-digital conversion module (62) is used for acquiring at a preset acquisition frequency, preferably by adopting a National Instruments data acquisition system, and the signal conditioning module (61) is preferably realized by adopting a hardware module for conditioning the loading sensor signal.
4. The synchronous acoustic emission and high-speed imaging monitoring system for fracture test of claim 1, wherein the peak detection algorithm is configured to detect a maximum point in a real-time sequence of load signals and output the trigger command when the load is detected to change from increasing to decreasing.
5. A fracture test acoustic emission and high-speed imaging synchronous monitoring method is characterized by comprising the following steps: S1, a fracture test monitoring system is built, a loading sensor (2) is assembled between a loading test device (1) and a sample (5), an acoustic emission sensor (31) is attached to the surface of the sample (5), a high-speed imaging device (4) is aligned to a monitoring area of the sample (5), and a synchronous control system (6) is respectively connected with the loading sensor (2), an acoustic emission acquisition instrument (32) and the high-speed imaging device (4) through electric connection to establish a signal transmission link; S2, starting the loading test device (1) to apply load to the sample (5), and continuously collecting load signals output by the loading sensor (2) by an analog-digital conversion module (62) in the synchronous control system (6) at a preset time interval delta t to form a continuous real-time load signal sequence; S3, a peak detection algorithm is built in a control module (63) of the synchronous control system (6), the load change trend of the current sampling point and the previous sampling point is judged in real time based on the real-time load signal sequence, and the critical state that the load is changed from increasing to decreasing is identified; S4, judging whether the load change trend meets a preset peak value judging condition, if not, returning to the step S2 to continuously acquire load signals and judge the trend, and if so, judging that the load change trend is a fracture key triggering moment, and executing the step S5; s5, the synchronous control system (6) generates synchronous pulses (7) through a digital-analog conversion module (64), and the synchronous pulses (7) are simultaneously transmitted to the acoustic emission acquisition instrument (32) and the high-speed imaging device (4) through electrical connection; S6, the acoustic emission acquisition instrument (32) records the synchronous pulse (7) to establish a time reference, synchronously acquires and stores acoustic emission data generated in the breaking process of the sample (5) and transmits the acoustic emission data to the computer (8), the high-speed imaging device (4) starts image acquisition according to a preset frame rate by taking the synchronous pulse (7) as a trigger instruction, records visual data of crack initiation and expansion of the sample (5), and transmits the visual data to the computer (8); And S7, the computer (8) performs time alignment processing on the received acoustic emission data and the high-speed image data based on the unified time standard corresponding to the synchronous pulse (7), and provides synchronous data support for fracture mechanism analysis through accurate matching of the acoustic emission data and the image frames.

Description

Acoustic emission and high-speed imaging synchronous monitoring system and method for fracture test Technical Field The invention relates to the technical field of high-precision measurement, in particular to a fracture test acoustic emission and high-speed imaging synchronous monitoring system and a monitoring method. Background Brittle media such as materials and rocks often accompany microsecond-level crack initiation and rapid propagation events during tensile or fracture failure. Acoustic emission (Acoustic Emission, AE) monitoring can record elastic wave information generated by crack evolution with higher time resolution, but is difficult to directly present crack morphology and propagation path, and high-speed imaging can visually record crack propagation morphology, but if a unified time reference with acoustic emission data is lacking, accurate correspondence of acoustic emission event-image frame is difficult to realize. In the existing fracture test, the high-speed camera and the AE system are commonly used for collaborative collection in a mode of independent triggering, manual triggering or synchronous starting of a flow layer and the like. Under the working conditions that the fracture usually occurs near a load peak value and the crack propagation process is extremely transient, the mode can face the conditions of fluctuation of trigger time, insufficient critical transient coverage or large alignment error of multi-source data in certain scenes, so that the fine analysis of fracture initiation and propagation mechanisms is affected. For example, chinese patent document CN110186957B discloses a synchronous information acquisition processing system and method, which is oriented to a fatigue test scene, and is implemented by cooperatively controlling the acquisition of detection devices such as a high-speed camera, a thermal imager, an industrial camera, and the like by a lower computer, and generating a corresponding control instruction of the detection device based on output voltage data of the fatigue tester. The method provides an implementation thought for cooperative control of multiple detection devices, but trigger criteria and control logic of the method are mainly developed around fatigue tester signals and threshold settings, and for a specific implementation mode of taking a load peak value as a trigger basis in a fracture test and establishing a unified hardware time reference between an acoustic emission system and a high-speed camera, further design and integration of the method and the device are still needed to be combined with specific test objects in view of the disclosure. For another example, chinese patent document CN113466044a discloses a method for testing explosive defect generation in the brazilian test, in which a light source, a high-speed camera and an acoustic emission instrument are arranged in the brazilian test loading process, and three actions of internal defect detection, end surface defect characterization and mechanical loading are synchronized, so as to obtain multiple types of data at the same starting time and perform parameter identification. The document emphasizes the synchronicity of multi-means collaborative characterization and test flow, and from its disclosure, its synchronicity is mainly flow-level synchronicity/collaboration, and for the establishment and recording of unified sync pulses or hardware-level time references for "frame-by-frame alignment", further configuration and calibration may be required in specific applications to meet the analysis requirements of higher time alignment accuracy. For another example, chinese patent CN110501218a discloses a hopkinson pressure bar system for measuring strain rate constitutive relation in an ultra-soft material, in which a high-speed camera and a camera trigger device are configured, the trigger device can use a laser velocimeter, a strain gauge, etc. to provide a trigger signal at a specific moment, and the trigger signal is processed by a waveform amplifier and an oscilloscope to trigger a shutter of the camera, and delay time can be set to meet shooting requirements. The publication is mainly directed to dynamic testing and imaging trigger control under the condition of medium strain rate, and the publication is not in the direction, and the disclosure of relevant details is relatively limited for the implementation path of incorporating acoustic emission monitoring into the same time reference and recording the synchronous pulse to the AE system simultaneously and used for triggering the high-speed camera. For another example, chinese patent document CN114581284a discloses a multi-camera high-speed synchronous shooting system and shooting method, which outputs a hardware control trigger signal to a plurality of cameras through a hardware synchronizer main board/slave board, so as to realize synchronous shooting under multi-camera, multi-viewpoint and high-speed conditions, so as to reduce po