横向应变对声双折射系数的影响分析

Analysis on the Impact of Transverse Strain on the Birefringence Coefficients

以时基延迟效应为基础的声弹法应力测量,对微小应变都非常敏感。整个加载过程中,横向微小应变引起的时间差会累积到声时检测设备中,给应力定量测量带来很大的误差。采用回振法对45号钢在拉伸和压缩状态下的声双折射现象进行了试验研究。在研究超声波垂直于应力传播过程中,建立了声时差与应力的关系模型,试验证明了该模型的正确性。利用声速与动弹模量及动泊松比之间的关系,引入了横向应变对声双折射系数的修正项。

Acoustoelasticity measurement of stress based on the technology of time delay is very sensitive to small strain.In the entire load processes,small time change caused by the transverse small strain may accumulate to the time equipment which shall result in greater error to measurement.When the ultrasonic wave propagating transversely to the applied stress direction,the model of time difference to stress was set up,and the acoustic birefringence phenomena on 45 steel under tension and compression were studied by Sing-Around method.In studying on the ultrasonic wave propagation perpendicular to the stress,one model of relationship between time defense and stress was established,the experiment proved the correctness of the model.The transverse elastic strain birefringence coefficient of acoustic correction term was introduced by using the relationship of velocity both with elastic modulus and with Poisson ratio.