中文摘要：

基于L_（cr）波声弹性理论,探讨缺陷及其尺寸对L_（cr）波评价应力的影响机理。结合＂当量法＂预制不同直径盲孔,采用互相关系数函数计算L_（cr）波时间差,通过线性拟合得到L_（cr）波声弹性系数,基于弹塑性变形和圆孔应力集中理论澄清盲孔直径对L_（cr）波声弹性系数的影响机理。结果表明：各直径盲孔L_（cr）波时间差随应力增大基本呈线性增加,但其非线性特征亦逐渐明显,线性阶段的最大应力值小于试样屈服强度;L_（cr）波声弹性系数随盲孔直径增大逐渐减小,并趋于平稳。分析认为,盲孔应力集中是导致上述结果的主要原因,试样各向异性组织及盲孔深度也是其重要因素。

英文摘要：

Based on Lcr wave acoustoelastic theory, the influence mechanism of blind-hole on stress evaluation with Lcr wave was discussed.Combined with equivalent method, the blind-holes with different diameters were preset, the difference in time of flight between Lcr wave was calculated by cross correlation coefficient function, the Lcr wave acoustoelastic coefficient was determined with linear fitting function, the influence mechanism of blind-hole diameter on Lcr wave acoustoelastic coefficient was clarified based on the elastic plastic deformation theory and stress concentration theory of hole.The results show that when the diameter of blind-hole is different, the change rule of the difference in time of flight between Lcr wave is basically the same as stress increases, the difference in time of flight between Lcr wave increases linearly as stress increases, while the nonlinear feature is also gradually obvious, the maximum stress in linear stage is less than the yield strength of specimen, the Lcr wave acoustoelastic coefficient decreases gradually as blind-hole diameter increases, and it tends to be constant.The analysis shows that the stress concentration is seen as the main reason for above results, anisotropic structure of specimen and blind-hole depth are also the important reasons for that.