Contact stress ultrasonic detection method based on contact acoustic resistance model

Abstract

The size and distribution of the contact stress at the assembly interface will directly affect the connection performance of the mechanical joint. However, the rough assembly interface presents strong dielectric discontinuity and material nonlinearity, which become the bottleneck restricting the development of contact stress detection. How to obtain contact stress by nondestructive testing means has become an urgent problem to be solved. In this paper, a multi-layer interface contact stress detection method based on contact acoustic resistance model is proposed to solve the difficult problem of rough interface contact stress detection. Firstly, based on the formation mechanism of contact acoustic resistance of rough assembly interface, the equivalent contact acoustic resistance expression of contact layer is derived. Secondly, the contact mechanism of rough assembly interface is clarified, and the mapping relationship model between contact acoustic resistance and contact stress is constructed. On this basis, according to the transmission law of ultrasonic wave at different interfaces of multilayer acoustic impedance, the expression of acoustic transmission coefficient at the interface of variable acoustic impedance is obtained. A contact stress detection method based on contact stress-contact acoustic resistance coefficient and acoustic transmission coefficient is proposed. The correctness of the theoretical model is verified by the tensile testing machine, and the maximum error is 15.52 %. This method will provide powerful data support for the evaluation of assembly interface connection state.