| Metal components are widely used in mechanical,electrical,aviation,aerospace,transportation and other fields,and their material properties directly affect the performance of related equipment.The existence of residual stress will have a profound impact on the physical properties of metal materials,resulting in their cracking or deformation,thus increasing the probability of failure of key equipment,seriously affecting people’s daily production and life.For this reason,this paper has carried out the research of residual stress detection technology,proposed a high-precision residual stress detection method based on eddy current method,and focused on the research of high-performance residual stress detection platform based on Zynq on-chip system.The main research work is as follows:(1)The basic principle of residual stress eddy current testing method is described,and the overall design of testing platform is completed.Based on the strain effect,the mathematical model between the stress and conductivity of metal materials is established.According to the testing requirements,the function of the residual stress testing platform is analyzed,and the overall design scheme of the residual stress testing system based on eddy current method is proposed.The advantages of SoC scheme compared with discrete devices are analyzed in detail,and the SoC chip is used as the hardware platform to control and process the chip.SoC chip selection is carried out.(2)According to the proposed residual stress detection scheme,the hardware circuit of the detection platform is designed based on Altium designer software,and the performance of the circuit is simulated based on Multisim software to verify the rationality of the design.The hardware platform is divided into two parts: the main control module and the probe module,which are connected by shielded wire.The main control module mainly includes signal source circuit,AD acquisition circuit and high stability power supply circuit;the probe module mainly includes constant current power drive circuit,signal amplification and filtering circuit.Finally,the PCB is designed according to the designed circuit diagram.(3)The algorithm of signal generation and detection based on SoC is designed.Taking zynq-7020 on-chip system as the control module,the detection system software is designed based on vivado software,and the detection of weak signal is realized by digital lock detection algorithm.The functions of detection system software mainly include: detection parameter setting,excitation signal generation,data acquisition control,signal feature extraction and so on,which lay the foundation for residual stress detection.(4)Completed the test and experiment of the detection platform.The test results show that the output frequency error of the signal source is 0.1%,and the amplitude error of the signal acquisition is 1.38%.The residual stress test was carried out with the magnetic sensor as the sensing element and the aluminum alloy 7075 as the test piece.By changing the frequency of the excitation signal,the output signal amplitude of the magnetic sensor changes with the excitation frequency.The experimental results verify the feasibility of the design and the effectiveness of the detection platform. |
