HIGH VELOCITY IMPACT RESPONSE OF FIRE DAMAGED POLYMER MATRIX COMPOSITES

摘要

The structural integrity and impact resistance of composite structures used in a wide range ofrnapplications can be dramatically debilitated because of catastrophic events such as fire andrnimpact. Fire exposure can significantly reduce the structural integrity and impact resistance of arncomposite structure in a very short period (< 100 s). The char formed during fire exposure is veryrnporous and brittle, thereby providing minimal structural support to the fibers. This studyrninvestigates the post-fire high velocity impact (HVI) response of vacuum assisted resin transferrnmolded (VARTM) E-glass/epoxy balsa wood core sandwich composites. Sandwich compositesrnwere subjected to three different fire exposure periods (0 s, 100 s, 200 s) prior to HVI.rnUnexposed and fire exposed panels were impacted with a 16.65 mm diameter, 18.9 g sphericalrnprojectile. The HVI response, namely ballistic limit, was found to decrease significantly inrnsandwich composites when subjected to incremental fire exposure with a flame intensity of 80rnkW/m~2 and 800 ℃. Post-fire exposure and post-impact failure analysis revealed the firerndegradation of the front composite facesheets was very pronounced in the sandwich compositesrncompared to the back composite facesheet. This phenomenon is associated with the high amountrnof heat resistivity provided by the balsa wood core during fire exposure of the entire sandwichrnstructure.