Vibration of periodic truss structures

Abstract

Recent trends in underwater vehicle design suggest the use of truss-like structures, connected to the hull by a limited number of attachment points, to support vibrating machinery. This work investigates the dynamic behavior of a set of spatially periodic trusses of practical interest. As expected, experimental and numerical modeling shows that this periodicity causes the trusses to behave as mechanical comb filters in frequency. However, the multiple periodicities at work in the truss and impedance discontinuities at the truss joints cause the resonant peaks at low frequencies to widen significantly. The consequence of this effect suggests that trusses with varied strut lengths tend to a low-pass characteristic. This is confirmed by data from a truss with several strut lengths. [Research supported by ARPA and ONR.]