Spring-in variability due to variations in the residual stress field of contoured autoclave composite parts is a primary source of nonconformances that result in costly part-rework. The main driver of spring-in and warpage is the difference between through-thickness and in-plane cure shrinkage and thermal expansion. State-of-the-art finite element process modeling frameworks are capable of capturing this phenomenon, and thus could be used to predict variability in spring-in for contoured parts. However, simulations of full three-dimensional representations of these parts remain computationally expensive and are generally not tractable for manufacturing environments. The objective of this work was to develop a tractable process model for predicting spring-in variability in a representative contoured part. A formal model verification and validation framework was used to develop models to predict the final part state due to variations in the materials, lay-up, and processing. The models developed in this effort included a reduced-order finite element process model using the COMPRO® plug-in for ABAQUS and a general analytical model was implemented in ModelCenter® for use in a manufacturing environment. Although there remain variations in the materials and processes that the models were not able to capture, both the reduced-order model and analytical model were relatively successful at capturing trends in spring-in variability.
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