INVESTIGATION OF TOOL-PART INTERACTIONDURING AUTOCLAVE PROCESSING OF POLYMERCOMPOSITES STRUCTURES

摘要

Autoclave processing of large composite structures with high degree of dimensional controlrnrequires a good understanding of tool-part interaction. This paper presents the results of anrnexperimental study pursued to understand the tool-part interaction and its role in process-inducedrnwarpage. A friction test fixture, specially designed to simulate the autoclavernenvironment, was used to measure the static and dynamic friction coefficients at various timernintervals during processing. A variation of magnitudes of friction coefficients was observedrnwith a maximum value recorded for uncured composite; the magnitudes decreased withrnramp-up due to decrease in viscosity till minimum viscosity point. Beyond this thernmagnitudes increased until gelation after which it continually decreased to a minimum valuernfor the completely cured composite. Fractographic examination of the tool surface, afterrntesting, revealed a failure pattern that is consistent with the measured debond loads andrnfriction coefficients. These friction coefficients were used in a 3D process model developedrnby this group to identify the sticking & sliding conditions at the interface during processing,rnresulting in realistic predictions of interfacial shear stress, in-plane stress and warpage.