Optimization of process-induced residual stresses in automated manufacturing of thermoset composites

The present study investigates the effect of automated fiber placement process on the induced residual stresses in polymer-matrix composites. The robotic fiber placement is utilized to fabricate a total of 150 flat specimens. The specimens are then cured inside an autoclave. The incremental hole-drilling method is applied to estimate the maximum stresses induced in the laminates. Further, an optimization process is conducted based on the response surface method to minimize the generated stresses, while maintaining the highest production rate. A mathematical modeling of the relationship between the process parameters and the residual stresses is generated. The statistical analysis (ANOVA test) and sensitivity analysis are conducted to evaluate the generated model. The results show considerable effect on the stresses when changing the manufacturing process parameters due to the existence of in-situ curing and the change in material porosity. The optimization strategy could significantly decrease the stresses with maximizing the fabrication speed.