弹性波在螺栓搭接结构中传播行为的数值模拟

Following a severe loading condition, bolted joints in assembled structures can loosen or fail. Health monitoring method based on elastic wave propagation is regarded as an efficient way to detect bolt looseness damage. To establish an efficient bolt looseness damage detection method based on elastic wave, it is primary to understand how elastic wave propagating in bolted structures. In this paper, a lap-jointed beam is modeled with nonlinear coupled field FEM method, to study wave propagation in bolted structures. MFC transducers are modeled with coupled field elements, the contact surfaces are modeled with contact pairs. The results show that the nonlinear model built in this paper can simulate wave propagation in bolted structures properly; the simulation results match well with actual experimental signals. The nonlinear model is computationally costly to use for parametric or optimization studies, for this reason, a simplified linear model is built. A preliminary static analysis is conducted to determine the contact area, then nodes on the entire contact surface are bonded. The results show the linear model in this paper can simulate wave propagation in bolted structures properly too, and also can reduce computation costs. The propagation path, wave form and wave amplitude change a lot when wave propagation through bolted joints.