The Development Of Ultrasonic Device To Detect Welding Residual Stress

The development of science and technology puts forward higher and higher requirements on residual stress of welding components lossless in service examination, thus stress detection technology has made rapid development. A large number of methods in measuring stress are finding out and used in engineering practice such as hole method, cutting method, X-ray method, Backhaus law, photoelasticity and so on.Compared with other methods, the ultrasonic wave law of testing the stress has a lot of advantages, such as rapid detection, high accuracy, easy operation, no pollution and so on. So it is considered the most promising means of non-destructive testing stress.This paper introduces the characteristics of ultrasonic and the critical refraction wave (LCR wave) generating mechanism, studies the acoustic elasticity theory, gets the calculation formula of ultrasonic testing welded residual stress by simplifying and deriving stress-sound velocity related formula, and demarcates the acoustic elasticity coefficient of the formula at the same time.On this basis, the paper designs hardware circuit and software routine of ultrasonic stress measurement system, and introduces work flow and gross structure of the intire system in detail. It explains explicitly principle and parameters of the ultrasonic wave stimulation module, the echo pretreatment module, the time survey module and so on, and tests their function. It also introduces the internal structure, measuring principle, working pattern and so on of high accuracy time figure chip--TDC-GP1 in detail.This paper designed the welding residual stress detection system, tested respectively the propagation time of LCR waves traveled in aluminum alloy specimens with/without the stress , calculated the welding residual stress of aluminum alloy specimens by the formulas, and got the distribution trends of the the welding residual stress.