RESPONSE OF MULTIELEMENT FOAM-FILLED PREFORM RTM STRUCTURES .2. LOW-VELOCITY IMPACT AND POSTIMPACT CRUSH RESPONSE

Resin transfer molding has opened the potential for structures incorporating multi-element preform architectures and cores, tailored for combinations of requirements that would not previously have been possible in one structure. The response of foam-filled RTM structural elements to low-velocity impact and post-impact progressive crush is investigated. Six different architectures based on a stiffened plate-type structural dement were tested, and comparisons of behavior prior to and after impact are made based on overall response and damage mechanisms. Differences in preform architecture are shown to result in differences in post-impact crush response through the triggering of damage modes that are architecturally driven. Failure mechanisms are seen to be driven by the use of a woven layer in the outer preform element, or through damage imparted to the central rib as a function of the damage events. Results based on the comparison of crush and post-impact crush response indicate that preform selection should be made based on architectural optimization linked to overall repeatability and uniformity of performance under a range of loading regimes for maximum efficiency in cases where structural stability and crush are important metrics of performance.