Numerical Study on Nonpermanent Joint Loosening in Structures with Base Excitation Using ۳D Finite Element Model

A critical occurrence is the loosening of the bolt joint assembly. It has the potential to inflict catastrophic damage in a wide range of industrial devices, particularly in the aerospace indus-try. The main goal of this paper is to investigate bolt loosening in constructions that are sub-jected to vibration. To do so, ABAQUS FE software is used to simulate a ۳D model of the lap joint specimen. Piezoelectric transducers are simulated in the model for receiving vibration and lamb waves. For simulating waves generated by vibrations through a bolted lap joint four static and dynamic steps are considered in ABAQUS. Several simulations for various pressures, ex-citation voltages, and contact frictions are performed. First, the effects of bolt load on wave transmission through bolted lap joints are investigated. The results demonstrate that in low pressures, transmitted waves through a bolted lap joint are disordered due to existing waves and non-ideal contact. Increasing pressure results in an improvement in contact between plates and waves are transferred more effectively through the lap joint. After that, the effect of stim-ulation voltages on wave transmission in particular pressure is investigated. The results show that raising the excitation voltage only changes the amplitude of the receiving signal but not its arrival time. Finally, the effect of contact friction on wave transmission at various pressures is investigated. The results demonstrate that increasing contact friction reduces signal arrival time while boosting peak to peak amplitude.