Ultrasonic Stress Detection Based On Electromagnetic Loading

Ultrasonic stress testing is a technique with many advantages,such as fast detection,non-radiation,low cost,portability,high spatial resolution and large detection depth.However,the coefficient of acoustic elasticity of the tested material must be obtained in advance,limiting the applied range of the technique.In order to solve this problem,a method of on line measurement of acoustic elastic coefficients based on electromagnetic loading is proposed,which can obtain the acoustic elastic coefficients of the tested workpiece in real time.Adopting this method,the complex additional work can be omitted and the errors caused by environmental factors can be eliminated to a certain extent.Ultrasonic wave stress measurement system based on critical refracted longitudinal wave is set up with variable angle ultrasonic probe.Transmitting and receiving of critical refracted longitudinal were realized and a program for calculating ultrasonic velocity was programmed.The relationship between stress and critical refraction longitudinal wave in 1060 Aluminum plate was studied and the coefficient of acoustic elasticity of the material is obtained.An axial electromagnetic loading device based on the electromagnetic induction principle with symmetrical structure and a pulse excitation power supply based on RLC oscillating circuit were designed.Finite element simulation model of electromagnetic loading on aluminum plate was established with Comsol,the distribution and the change over time of stress were obtained.According to the simulation results,the axial electromagnetic loading system for metal p lates was fabricated and optimized.An electromagnetic loading experiment platform was built and its performance was tested.The tensile and compressive stress on 1060 Aluminum sheets were measured.The acoustic elastic coefficient of 1060 Aluminum sheet with residual stress was measured with the experiment platform.The experimental results are in good agreement with the results obtained by traditional method,verifying the feasibility of the scheme.