Multiscale characterization and representation of composite materials during processing.

Area of Science:

• Materials Science and Engineering
• Computational Mechanics
• Polymer Composites

Background:

• Residual stresses and dimensional changes are critical in composites manufacturing.
• Process simulation is essential for predicting and mitigating these effects.
• Various constitutive models and simulation approaches exist, each with varying complexity and applicability.

Purpose of the Study:

• To present and discuss the applicability of different constitutive models and simulation approaches for composites process simulation.
• To highlight practical considerations, including characterization and simulation costs.
• To detail the application of two specific approaches: pseudo-viscoelastic cure hardening instantaneously linear elastic (CHILE) and linear viscoelastic (VE).

Main Methods:

• Review and discussion of existing constitutive models (elastic to nonlinear viscoelastic) and simulation approaches (separated to multiscale integrated phases).
• Detailed presentation of the CHILE and VE models.
• Application of these models to analyze residual stress formation in different cure cycles for HEXCEL AS4/8552.

Main Results:

• The CHILE model accurately predicts residual stresses in simple cure cycles (e.g., one-hold) for materials without devitrification.
• Modifying cure cycles using the CHILE approach can reduce residual stresses and enhance mechanical performance.
• A more complex VE model is necessary for cure cycles involving material devitrification during post-cure.

Conclusions:

• Model selection for composites process simulation depends on the complexity of the cure cycle and material behavior.
• Simpler models like CHILE offer cost-effective solutions for specific applications, enabling optimization of cure cycles.
• Advanced models like VE are indispensable for accurately simulating complex processing conditions and material transformations.