It is widely confirmed that guided elastic waves are of great interest for structural health assessment in active and passive approaches. However, multimodal and dispersive character of wave propagation make data processing, analysis, and interpretation difficult. Therefore modelling and numerical simulations of Lamb wave propagation is of great research interest. The frequency-dependent spectral characteristics are fundamental to identify modes that propagate for a given frequency range with low dispersion and low attenuation. In all numerical models of guided wave propagation errors associated with discretisation, boundary conditions approximations, or mesh topology are inevitable, affecting spectral properties. Therefore it is always critical to asses the impact of these parameters/conditions on numerical solutions.

Recently, a generalised approach – based on finite difference Local Interaction Simulation Approach (LISA) approach for exact numerical spectral (i.e. dispersion and excitability curves) estimation has been proposed in [Ref. JASA, SPIE]. The approach solves the eigenproblem for the wavenumber- frequency pairs, using iterative equations of a given numerical method. Since numerical simulations explicitly involve model discretisation parameters their influence on guided wave propagation characteristics can be investigated.