# Principle of Virtual Work for a General Deformable Body - a Simple Proof

*Some of the long-standing teaching problems in structural engineering degree courses are associated with the principle of virtual work. This paper presents a simple proof of the principle for a general deformable body. The proof, which is sufficiently simple for undergraduate teaching, is based on two simple results in engineering mechanics and the exploitation of the concept of virtual displacements to include the use of physically impossible displacements. It is hoped that the paper will contribute towards the teaching of the theory of structures in the universities and polytechnics, and help to remove the misunderstanding of the principle of virtual work which is, at present, widespread among structural engineering students.
F.K. Kong, J.M. Prentis and T.M. Charlton*