WAVE-PROPAGATION, POWER FLOW, AND RESONANCE IN A TRUSS BEAM

Wave propagation in a periodic truss-work beam is investigated computationally. The analysis is based upon the transfer matrix of a single bay of the structure. The results, with members modeled as rods with pinned joints, agree well with results obtained from an equivalent continuum model of the same structure. The inclusion of bending in member models shows that both the pinned rod model and the equivalent continuum models lose fidelity above the first resonant frequency of lateral motion of the members. Boundary conditions are applied in wave-mode co-ordinates by reformulation in terms of reflection matrices. The phase closure principle is invoked to predict natural frequencies of a fixed-free portion of the truss. It is found that closely spaced resonant frequencies are not identified by this method.