Evaluation and compensation of process-induced deformation in U-shaped woven composite sandwich structure during autoclave co-bonding

Curvature composite structures are susceptible to deformation during the curing process which could lead to assembly failures. In this study, the process-induced deformation and the subsequent deformation compensation of a double-curved U-shaped woven composite sandwich structure during autoclave co-bonding are investigated numerically and experimentally. In the curing simulation, the effective modulus and cure shrinkage of 8-harness satin (8HS) woven composites are solved using the degree of cure (DoC)-stepping algorithm. Considering the effects of co-bonding process, the outer skin is first cured through the multi physics model, and then the residual stresses generated from the outer skin are loaded as a pre-defined stress field into the curing of inner skin. The simulation results of the deformation coincide with the measurement results of the manufactured part. A sensitivity analysis is conducted on the effects of residual stresses transferred, temperature gradients, and changes in material properties. Based on the deformation evaluation method, the tool is trimmed in reverse to realize deformation compensation. The validation results show that the geometric accuracy of the U-shaped woven composite sandwich structure can be significantly improved by the multi step iterative compensation process. This numerical-based compensation strategy provides new insights into high quality manufacturing and reducing the cost of repetitive trial-and-error.