Compressive Strengths of In-Situ Cured Graphite/Epoxy and Glass/Epoxy Composite Cylinders

Abstract

In this paper, the compressive strengths of in-situ cured composite rings using a simple mechanical text fixture are presented. Reported results include T300/epoxy as well as E-glass/epoxy hoop-wound composite rings. A J₂ deformation theory of plasticity is employed in the stress analysis of the compliant ring while linear elastic response is assumed for both the composite ring and stainless steel. Two objectives are included in the current study: first is the study of the compressive strengths of hoop wound fiber-reinforced thermoset composite rings made by in-situ curing method and correlate the compressive strength to the processing parameters; second is the quantitative assessment of the effect of residual stresses on the compressive strengths of composite rings.

Experimental results indicated that composite ring failed initially by shear mode at the outer surface and propagated through-thickness. The kink band formation, followed by the shear failure, aggregated the failure zone. Finally layer delamination developed and led to a catastrophic failure of specimen. Most of the reported compressive strengths of unidirectional composites are based on unidirectional laminate composites. The current study represents one of the few works involving the composite ring specimens. Experimental results indicated that the compressive strengths of in-situ cured composite rings are very close to the compressive strengths of unidirectional laminates. This indication suggests that in-situ curing method can be used to produce high quality composite structures. Also the compaction pressure is found to have great influence on the measured compressive strength.

Keywords

compressive strength measurement graphite/epoxy glass/epoxy continuous cure hoop wound cylinder ring complaint ring T300 UF3327 tow tension compaction pressure effect of process parameters

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