Effective non-reflective boundary techniques for effcient simulation of guided wave propagation
Simulation study of wave propagation in structures can provide insights for structural health monitoring system design, developing an efficient simulation toolbox for the purpose thus becomes very essential. This paper addresses the practical issue of simulating guided wave propagation in an infinite domain using non-reflective boundary (NRB) techniques, based on the simulation framework of local interaction simulation approach (LISA) that is currently being developed in our lab. Existing NRB methods can be divided into two categories, i.e. non-reflective boundary conditions (NRBC) and absorbing boundary layers (ABL). Two basic NRB methods from the above two categories will be discussed in the paper, i.e. the Lysmer-Kuhlemeyer (L-K) model and the absorbing layers with increasing damping (ALID) method. Their implementations in the framework of LISA will be detailed in the paper. Then hybrid NRB techniques will then be developed that aims to take full advantage of the potentials of each method and improve the absorption while maintaining same computational efficiency. The first hybrid approach is proposed that combines the Lysmer-Kuhlemeyer (L-K) model and the absorbing layers with increasing damping (ALID) method. The modified L-K (MLK) method that extends L-K model on both and bottom surface of the plate structure will be presented next. The performance of these NRB methods will be compared to the case with free boundaries on both isotropic and composite plate. The first hybrid method also leads to an easier way for choosing the proper maximum damping coefficients for ALID method. These coefficients are otherwise guessed based on user’s experience. Case studies on isotropic plate structure are given, with excitation respectively as narrow and broad frequency signals, for both symmetric and anti-symmetric wave modes. Discussions on choosing proper parameters for the NRB methods are given as well. A comprehensive case study involving piezoelectric-coupled simulation and contact model on the isotropic plate and also composite structures are presented later as validation of effectiveness of the NRB methods on complex structures.
