wave motion and stop-bands in pipes with helical characteristics using wave finite element analysis

Pipes are widely used in many industrial and mechanical applications and devices. although there are many different constructions according to the specific application and device, these can show helical pattern, such as spiral pipes, wirereinforced pipes/shells, springsuspension, and so on. theoretical modelling of wave propagation provides a prediction about the dynamic behavior, and it is fundamental in the design process of these structures/devices and in structural health monitoring techniques. however, standard approaches have limitations in terms of difficulties in modelling and impossible computational cost at higher frequencies. in this study, the wave characteristics in waveguides with helical patterns are obtained using a wave finite element (wfe) method. the method is described for a 1d and 2d waveguide with helical properties and it is illustrated by numerical examples. these include the optimization of stopbands for a fluidfilled pipe with concentrated masses and a cylindrical structure with helical orthotropy.