Tooling geometry optimization for compensation of cure-induced distortions of a curved carbon/epoxy C-spar

The respect of the manufacturing tolerances is a challenging issue due to the complex distortions caused by the curing process, being sometimes a major obstacle to an increasing use of composites in aeronautics. The cure-induced distortions are modeled and mitigated owing to the development of a computational mold compensation strategy. An in-house surrogate-based optimizer coupled to three-dimensional curing simulations, is used to iteratively alter the shape of the mold in order to minimize the discrepancy with respect to the nominal geometry. Two parametrization strategies are proposed and applied to a generic curved C-spar geometry. One strategy consists in the characterization of the major distortion modes caused by the curing process, and in the parametrization of the geometry to compensate for each mode. The other strategy is to select a number of control points which can move freely in space to find the optimal configuration. Each method performs well but in a different manner, and the optimal choice depends on the industrial specifications of the problem.