残余应力对光弹实验中超声图像的干扰分析

Analyses of the interference by residual stresses on ultrasonic images in photoelastic experiment

动态光弹成像技术是观测固体内部超声应力场的重要手段,然而样品在制作过程中会产生残余应力,给观测带来一定干扰,特别是缺陷附近的应力集中效应,使得缺陷散射声场的研究更为困难。本文利用线性应力理论分析了超声应力与残余应力的相互关系,并推导出该叠加应力场在光弹系统中的光强表达式,通过实验验证,证明了该理论的可行性。本文结果可为应力集中区域的散射声场分析提供借鉴。

Dynamic photoelastic imaging technique is an important method to study the ultrasonic stress field in solids. However, the residual stresses in samples, which are generated in the fabricating process, bring strong background noises to the experimental result. Particularly, it is significant in the vicinity of defects caused by the stress concentration effect. The interaction between ultrasonic and residual stresses has been analyzed applying the linear stress theory. Then, the expression of the light intensity of the superposition field in the photoelastic system has been derived and verified by experiments. The results may provide a guidance for the analyses of the ultrasonic scattering field in the region of the stress concentration.