Active control of cure-induced distortion for composite parts using multi-zoned self-resistance electric heating method

High dimensional accuracy of the carbon fiber reinforced polymer (CFRP) composite parts has been a long-term challenge for manufacturers in the aerospace industry. Traditionally, the uneven curing temperature could aggravate the cure-induced distortion (CID) and should be avoided as much as possible. But even under an ideally uniform temperature field, the CID of curved parts still cannot be eliminated because of the anisotropic shrinkage nature of the CFRP laminate. In this work, a novel CID control method based on the multi-zoned heating methodology is proposed, which actively applies an optimized non-uniform temperature field in different zones of the part to counteract the CID influenced by geometric structures. The counteracting principle of the proposed method lies in that using the actively formed through-thickness temperature gradients in different zones generates numerous small local thermal deformations, and their combination can significantly reduce the overall CID of the CFRP part. A co-optimization framework combined with the numerical model and genetic algorithm is established to rapidly compute the optimized multi-zoned temperature field for the CFRP parts with arbitrary complex structures. A good agreement between the numerical and the previous experimental results shows the effectiveness of the numerical model, and the multi-zoned temperature field optimization case of a scaled air-intake CFRP part demonstrates the performance of the co-optimization framework. Finally, by using the multi-zoned self-resistance electrical heating method, the CID reduction of the proposed method is experimentally validated on a complex CFRP part, where the average displacement reduces by >60 % compared to that of the traditional oven process.