UBC Theses and Dissertations
Modelling and experimental issues in the processing of composite laminates Smith, Gregory David
Two published resin flow models for the autoclave/vacuum degassing process (AC/VD) have been implemented in a user friendly computer code. One, the sequential compaction flow model (SCM), includes a heat transfer model and the other, the squeezed sponge resin flow model (SSM), has been extended to include the same heat transfer model. An expression has been derived that makes the SSM mimic the resin pressure and lamina thickness predictions of the SCM. A parametric study of the effect of the lamina stress-strain behavior on the predicted resin pressure and laminae thickness profiles as a function of time has been conducted. The lamina stress-strain behavior has been found to greatly influence the compaction behavior of the laminate. Laminae with hardening stress-strain behavior, which is characteristic of real laminae, have the fastest compaction times. The predictions of the flow models have been compared to experimental laminates. Three laminates, two 24 and one [0/902/0]12, were laid-up with small postage stamped sized pressure sensors placed at the upper and lower surfaces and at the 1/4, 1/2 and 3/4 points through the thickness of the laminates and cured by the AC/VD process. The cure cycle was then simulated by the SCM and SSM models and their predictions compared to the sensor response monitored during the cure cycle. The experimental resin pressure profiles for both laminates showed that the resin flow begins very early in the cure cycle, much earlier than predicted by the SCM and about the same as predicted by the SSM. The laminate mass and thickness at the end of the cure cycle have been compared to the model predictions for all three laminates. For the 48 ply laminate the laminae thicknesses have also been compared to the model predictions. In all cases the best agreement was for the SSM model.
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