Teaching students work and virtual work method in statics: A guiding strategy with illustrative examples

Abstract

A virtual displacement is an imaginary differential displacement that may not really take place. A virtual displacement may be either consistent with constraints at supports or inconsistent with constraints at supports. A virtual work is the work done by force or moment during a virtual displacement of the system. The virtual work method can be applied to solve problems involving either machines (structures with movable members) or frames (structures with no movable members). By letting the free body of a system undergo a strategically chosen compatible virtual displacement in the virtual work method, we can solve for one specified unknown at a time in many complex as well as simple problems in mechanics without having to solve coupled simultaneous equations. The virtual work method may initially appear as a magic black box to students, but it generally kindles great curiosity and interest in students of statics. This paper proposes an approach consisting of three major steps and one guiding strategy for implementing the virtual work method. It results in great learning of the virtual work method for students.