Curing of thick composite prosthesis : measurements and effects of exothermic reaction on thick carbon composites

Abstract

During the curing of thick composite laminates a quite significant amount of temperature overshoot can occur in the middle of a thick part. This is a result of the resin in the composites being exothermic meaning that when the resin cures it releases a significant amount of heat. This problem is compacted due to the fact that the carbon/glass materials have very low thermal conductivity resulting in temperature lag and then a significant overshoot. The overshoot is often well over the highest recommended temperature for the composites often resulting in degradation of the material and therefore a lower quality product. Other problems that can occur are warping and spring back. Lastly the consolidation period of thick composites might be longer than with conventional thinner laminates. Therefore a longer consolidation period might be needed for better resin flow and in turn a better performing part. In this thesis the affects of the current curing cycle has on the products that Össur produces will be examined. A recommendation will than be produced from the tests performed as to an improved production cycle. This change will optimally not lengthen the production cycle too much and will take in to consideration different feet that Össur produces.