About the origins of residual stresses in in situ consolidated thermoplastic composite rings

In a context of cost reduction, in situ filament winding of thermoplastic matrix composites becomes an appealing process. As residual stresses could considerably affect the produced part, models were proposed to predict process-induced residual stresses. After developing a validated thermal model of the process, mainly three different aspects are here addressed: the continuous bonding occurring during the process, the effect of the processed layer on the structure, and the effect of the curvature of the mandrel. While stresses coming from the continuous bonding appeared to be negligible, consequent levels of stresses can be achieved due to an iterative compression of the structure by the tow (supposed to be under tension). The mandrel properties and the tow tension profile followed during winding are essential parameters that might induce several different stress states. A comparison between measured and computed end-to-end openings of split rings illustrates the accuracy of the proposed models.