Study On Two-dimensional Stress Nondestructive Testing And Temperature Influence For Members Of Steel Structure Based On Ultrasonic Method

The real-time stress measurement of steel structure is of great significance to ensure the safety of the steel structure. There are several traditional stress detection methods, such as: X-ray method, the magneto-elastic method, the resistance strain gage, hole-drilling method and so on. However, considering the nondestructive testing for steel structures within the initial stress, the above methods all have some disadvantages. Aiming at these problems, in view of the application of ultrasonic method using in the field of detecting welding residual stress, bolt fastening stress and wheel bolts stress, in this paper, an idea of using ultrasonic method to detect the two-dimensional stress of steel structures component is put forward, and its influence factors are studied. The main content are the following three parts:The construction of the stress testing system based on ultrasonic stress measurement method. The construction of the stress test system in this paper is based on the theory of stress testing to steel structure component, including hardware system and software system, and do several improvements to the system, such as control the distance of the transmission of ultrasonic and the measurement of the ultrasonic transmission time. The vernier caliper probe has been made in order to control the path accurately to 0.01 mm; Measured the ultrasonic propagation time in organic glass of probe to improve the test accuracy.The detection of two-dimensional stress tests and validation for steel structure component based on ultrasonic method. The two-dimensional stress testing mentioned in this paper mainly refers to the stress distribution of the material along the depth direction. First, using the method of digging groove on the plate to demarcate the propagation depth of different frequency Critical refraction p-wave, the error is within 0.5 mm; Then design artifacts and loading device, create a stress field which has a variation along the depth of the material, using different frequency ultrasonic probe to detect the stress of different depth on the U steel component, test results accord with the results of numerical simulation. Put forward the detecting depth of different frequency critical refraction p-wave. Analyses the error may cause in the process through the test, puts forward some matters need to pay attention to in the experiment.The research on the effects of temperature factors on ultrasonic stress testing method of steel structure components. Based on the existing formula for ultrasonic method stress detection, considering the influence of each variable of the formula, under the influence of temperature, new stress testing formula is deduced, and measured the ultrasonic propagation time of the zero stress state under the temperature of 25℃~75℃, sum up the temperature change rule, use the new formula which considers the change in temperature, testing four groups of components stress under different temperature, and compare with the test results of resistance strain gauge. The results show that the stress test results measured was consistent with strain gauge, the formula is reliable.