Unit Load Method for Deflections of Planar, Nonlinear Structures

Abstract

The unit load method, which is also known as a virtual work method, as well as by several other names, is a widely used tool for calculating deflections of linear structures. A procedure is developed here, which consists of similar steps and can be used when nonlinear material is involved. The formulae are developed based on the concept of complementary energy and the Castigliano theorem extended to nonlinear systems. A few simple examples are solved using this method and the results are compared with those obtained by a finite-element program. It appears that a blend of both types of analysis may be the optimal tool in many situations.