Characterization of residual stresses in a composite curved sandwich beam

Residual stresses are of great importance in ensuring geometrical stability of sandwich structures. Indeed, creep phenomena occur after manufacturing and can lead to unexpected deformations in sandwich shells. In order to assess these, a first experiment has been performed on the shell to provide an order of magnitude indication of the residual stresses by means of cutting to release the stresses. This approach is then extended to a sandwich beam extracted from the shell. This is completed by the thermo-mechanical characterisation of the skins in order to provide the properties required for modelling. Finally, a three-dimensional finite element model is presented, which includes both thermal and mechanical behaviour. Comparisons are made between the model and a heating experiment on the sandwich beam. The thermo-mechanical response of the beam is found to be particularly sensitive to the thermal properties of the constituents.