3 - The origins of residual stress and its evaluation in composite materials

Abstract

Many factors contribute to the formation of residual stresses in laminated composites, including the mismatch of free strains due to the thermal changes and phase changes during the manufacturing process. In this chapter, the factors that contribute to the development of residual stresses along with the state-of-the-art experimental approaches to measure and/or monitor them are reviewed and discussed. Effects of these stresses including dimensional changes and also the reduction in mechanical performance of the final products are discussed, and mitigation strategies to remedy these effects are reviewed. It is shown that by understanding the effect of the various parameters on residual stress development, it is possible to reduce the amount of residual stress and consequently increase the mechanical performance and design allowables of the matrix.