ABSTRACT
The determination of the state of stress in structural materials during service has always been one of the key issues that the structural engineer or designer has to address. The lack of experimental techniques in this area often forces the engineer to resort to analytical or numerical methods to assess the overall stress distribution within a structural component. As a result, stringent design rules have to be applied to ensure safety in a structural assembly. This is particularly well demonstrated in the case of advanced fiber composite materials; the lack of knowledge of the complex state of stress generated by the anisotropy and quite often inhomogeneity in these materials leads to overdesign and hence high component costs. Thus, in polymer based composites, the savings gained in moving parts as a result of their light weight and correspondingly high specific properties, can quite often be offset by the volume of material required to address the safety design limits.
