Nonlinear Deflection Analysis for Coupled Tubular Structures

An analysis is presented for determining the large, transverse deflections of tubular structures that are mechanically coupled at discrete locations along their length. The nonlinearities treated are characteristic of the limiting nature of frictional and spring-type coupling. Tubular structures are analyzed by considering the assembly of tubes to be subdivided into axial segments between adjacent coupling locations. The governing relationships are developed for tubular structures consisting of any number of different types of tubes. The end product is a well-behaved linear system of equations, which is solved under iteration of applied loading for the nonlinear, transverse deflections of each tubular segment. Reactor fuel assemblies are considered for specific examples of coupled tubular structures, and numerical results are compared with experimental measurements of actual assemblies to demonstrate the accuracy of the analysis.