Research On Ultrasonic Testing Method Of Residual Stress In Different Depth For Metal Material

With the development of science and technology,much mechanical equipment has been widely used.With the use of these mechanical devices,the security risks of the components are gradually revealed,such as the leakage of natural gas pipeline,fatigue damage of the engine blade,fracture of transmission shaft in military vehicle,which caused great harm to state property and people’s lives.Therefore,the research on the nondestructive testing（NDT）technology and methods for key components in the national key infrastructure and defense equipment has great social and economic value.The residual stress is a very important factor in many factors which cause the structural failure and fracture of the mechanical structure and the key components of mechanical equipment.So,it is necessary to detect the residual stress accurately.And the testing technique of residual stress not only has important theoretical research value,but also has the great significance for the improvement of production technology and safety factor of equipment.Ultrasonic testing technique of residual stress is a new nondestructive testing technology,which attracts wide attention of researchers both domestic and foreign in recnet years and achieves rapid development.However,the current research and application of residual stress testing mainly focus on the plane residual stress,while there are relatively few studies on the ultrasonic testing methods of residual stress in different depths.Therefore,the research work on ultrasonic testing of residual stress in different depths has the important realisitic significance and engineering application value for realizing the detection of residual stress distribution in the direction of depth.In this paper,there are the studies of ultrasonic testing methods for residual stress in the different depth for metal materials.It makes a more detailed analysis of the basic principle of ultrasonic wave propagation in elastic solids.Based on the theory of acoustic elasticity,the paper studies the basic principle of residual stress testing by ultrasonic and the principle of ultrasonic testing of residual stress in different depths for metal material.And this paper establishes a theoretical model of L_CR wave propagation with different frequencies in metal materials.Moreover,the paper sets up the related two dimensional finite element models according to the finite element analysis.It researches the propagation characteristics of L_CRR wave with different frequencies in metal materials and analyzes the testing depth of L_CRR wave with different frequencies in metal materials.And then,the paper establishes the model and method for ultrasonic testing of residual stress in different depths according to the testing depth of L_CR wave with different frequencies.According to the ultrasonic testing methods of residual stress in different depths,the paper builds the system of ultrasonic testing residual stress in different depths,and studies the cross-correlation and interpolation operations for received ultrasonic signals to realize the analysis and processing of ultrasonic signal and improve the accuracy of residual stress testing.At last,according to the above theoretical analyses and researches,the paper complete the experimental verification of the testing depth and propagation characteristics for L_CRR wave with different frequencies.And it also completes the experimental verification for ultrasonic testing of residual stress in different depths of metal materials.At the same time,the ultrasonic testing technology of residual stress is applied in engineering practice.