Numerical simulation and influence factors of curing deformation of thermosetting resin matrix unidirectional composite stiffened panels

In the process of autoclave molding, the response and evolution of uncured skin prepreg, cured stringer, and adhesive films under the action of thermal, chemical, and mechanical fields are different. In this paper, the simulation technology of residual stress and curing deformation are employed to address the curing deformation problem of civil aircraft composite stiffener plate. The analysis of the evolution mechanism of residual stress and curing deformation of T-type stiffened panels in the co-curing, co-bonding and secondary-bonding process, as well as the co-bonding process of I-type and hat-type stiffened panels are completed. The simulation results are compared with the results through the process experiments. The simulated maximum warping deformation value and the experimental results have an error margin of no more than 10% and the deformation tendency is almost the same. An experimental test method for model parameters and a simulation and prediction model for curing deformation of composite stiffened panels are developed. An analysis is conducted on the effects of varying molding processes and stringer configurations on the deformation of stiffened panels. The findings revealed that the deformation of the secondary-bonding process is the least significant, while the deformation of the hat-type stringer stiffened panels is the most substantial. It is further determined that the resin state and the R-corner region in the prepreg would influence the deformation outcomes.