粗糙接触界面超声非线性效应的概率模型

A probability model for ultrasonic nonlinear effects of rough contact interface

提出描述粗糙接触界面超声非线性效应的概率模型,利用分段均匀概率函数描述粗糙接触界面劲度系数变化,结合表面粗糙峰的几何分布特征,得到界面粗糙度和两侧表面相对运动对声波的非线性调制作用。实验观测了铝合金材料的粗糙接触界面的高次谐波现象和阈值现象,进一步分析了归一化非线性参数与界面加载压力、粗糙度之间的关系。实验测量结果与概率模型的理论预测一致,证明了该模型的正确性,为利用超声非线性效应评价粗糙接触界面提供了理论依据。

A piece-wise uniform probability distribution model for ultrasonic wave interaction with rough contact interfaces is proposed. Combined with microscopic geometric characteristics of rough contact interfaces, a piece-wise uniform probability function is utilized to describe variation of the contact interface stiffness, as a result the acoustic signal modulated by roughness and relative motion of the surfaces is obtained. Higher harmonics generation and threshold phenomena of the rough contact interface made up of aluminum alloy samples are observed, and the relationship between normalized nonlinearity parameter and pressure loaded on the rough interface ~f the different roughness is measured. The experimental data is consistent to the theoretical prediction, which demonstrates the piece-wise uniform probability distribution model can well predict the variation of nonlinearity parameter. This model may provide a theoretical foundation for further study on the nonlinear acoustic technique to evaluate mechanical properties of rough contact interface.