ABSTRACT
This chapter develops the general theory for the approximate solution to elasticity problems involving either plane stress, plane strain, axisymmetry or general three-dimensional elasticity. The St Venant's torsion problem is also discussed as a useful special class of restricted elasticity problem. There is a parallel development of the conventional theory using the contragredient principle and orthogonal interpolation functions, and the natural mode technique. Elements can be broadly classified (in so far as computations are concerned), into the categories of those which can have their stiffness matrices calculated explicitly; those which require numerical integration. These various domains were illustrated in some detail. The chapter concludes with a brief introduction to heat transfer because the topic is intimately connected with thermal stress analysis. The transient state is of more interest because it allows the calculation of strains which vary with time in problems where the heat source is not constant.
