Effect of Processing Parameters on the Iosipescu Shear Strength of Various Pultruded Glass/Epoxy and Graphite/Epoxy Composites

摘要

The intent of this study was to evaluate and compare the effects of processing parameters on the shear strength of several pultruded epoxy/graphite and epoxy/fiberglass composites systems. The processing parameters examined included those known to be most significant in commercial pultrusion manufacturing - pull speed, fiber volume and die temperature profile. Iosipescu and short-beam shear testing were performed on the product in the as-pultruded condition to determine the effect of pultrusion processing conditions on the measured shear strength. Average Iosipescu shear strength values for the graphite/EPON 9310 composites were the highest of the four systems examined followed by glass/EPON 862. The Iosipescu shear strength of graphite/EPON 9420 and glass/EPON 9500 overlapped with each composite system having the highest strength for approximately one-half of the process conditions examined. Process conditions involving lower fiber volume were determined to increase the shear strength of the pultruded product. Slower pull speeds increased the shear strength for the slower reacting graphite/EPON 9420 and glass/EPON 862 systems while faster pull speeds increased the shear strenght for the more rapidly curing graphite/EPON 9310 and glass/EPON 9500 systems. Die zone temperatures were found to have significant effects on the various composite systems with conditions favoring higher resin cure producing higher shear strengths. A comparison made between Iosipescu shear strength and short-beam shear strength showed a small difference for glass composites and slightly higher difference for the graphite composites, with short-beam shear strengths being higher in all cases.