EXPERIMENTAL INVESTIGATION OF TOOL/PART INTERFACE DURING CURING OF COMPOSITES

摘要

The mismatch of coefficient of thermal expansion (CTE) between tool and part is one of the known causes of residual stress during cure of composites. As a consequence, geometrical distortion of the part will be induced. In order to accurately estimate process induced stresses and distortion of composites, the friction force between tool and the part should be known. To determine the coefficient of friction (COF) in the tool/part interface, a device was developed to mimic the autoclave process and to obtain the friction force at any point during the cure cycle. This device can apply user-defined pressure and temperature cycles, and it measures the force and displacement between part and tool. For this experimental investigation, a commercial prepreg (Cytec 977-2 UD) was subjected to a cure cycle, and the COF between part and tool was obtained at different times during cure. The results were in good agreement with the development of mechanical properties during curing.