Abstract
Stressed-skin constructions in which low modulus thin laminates of composite materials are shaped to provide stiffness to the overall structure have been utilised for a number of years. There have not been any rigorous analytical or mathematical solutions to solve this structural problem; it is generally investigated by an approximate method such as substituting the continuum comprising the structure into an analogous skeletal one. Although this method indicates the stress level in the structure and deflections of the overall construction, careful estimates of the equivalent areas of the skeletal structure have to be made. More detailed information concerning stresses and deformations within the continuum may be provided by the finite element model. Both experimental and finite element techniques have been used to examine the stresses and the deformations within a loaded structure. The finite element method has been developed to allow for both inplane and bending stresses to be considered. Within the continuum of a complicated shape, in the form of a tetrahedral unit which comprised the basic units for a structure, results from this analysis have been compared with those for an experimental model under static loads. In the analytical model, it was found that particular care had to be taken when deciding the degree of fixity of the individual units to their neighbours, and it was assumed that full fixity was developed. In the experimental model, however, the units were bolted and it is shown that this type of connection gives an order of magnitude of larger defelections than that for the analytical model. The agreement between the analytical and experimental stresses and deflections was not good due to the coarse mesh that was used in the finite element analysis and which affected the boundary conditions of the units. A more realistic idealization of the structure in which bolts are used to connect individual units could have been simulated by the utilisation of a very much finer mesh but this would have greatly exceeded the core capacity of the electronic computer. It is suggested that the structure be analysed on a larger capacity computer.