PolymerTesting23(2004)719–725 www.elsevier.com/locate/polytest MaterialBehaviour Eﬀectofstrainrateonthecompressionbehaviorofawoven glassﬁber/SC-15composite M.Guden a,b,  ,U.Yildirim a ,I.W.Hall c a Mechanical Engineering Department, Izmir Institute of Technology, Izmir, Turkey b Center for Materials Research, Izmir Institute of Technology, Izmir, Turkey c Mechanical Engineering Department, University of Delaware, Newark, DE, USA Received14October2003;accepted3January2004 Abstract Strain rate dependent compression behavior of a plain-weave S-2 glass fabric SC-15 epoxy (rubber toughened resin) composite plate, currently studied as the backing plate for composite armor applications, was determined in the through-thickness direction (normal to the ﬁber plane) in the strain rate regime of 1  10 4 to1:1  10 3 s 1 .In thestudiedstrainrateregime,themodulusandfailurestrengthofthecompositewerefoundtoberatesensitiveand increased with increasing strain rate. Microscopic observations showed that the composite failed by ductile failure, involving matrix cracks and, later, cracking through and between the ﬁber layers. Crack deﬂections at rubber par- ticle/matrixinterfaceandparticlepull-outwereobservedinthefailedsamples,contributingtothetoughnessofthe composite. # 2004ElsevierLtd.Allrightsreserved. Keywords: S-2glass;SC-15epoxy;Composite;Compression;Highstrainrate 1. Introduction Modern composite armor, typically consisting of a combinationofahardfacinglayerofceramictilesand a ﬁber reinforced composite backing plate, is under development to satisfy ballistic and structural require- ments,whileprovidingweightsavingsofapproximately 30–40% [1]. The function of the ceramic layer is to deformanderodetheprojectileandtherebyreducethe localpressureinthecompositebackingplate.Thecom- posite layer absorbs a signiﬁcant part of the kinetic energy of the projectile by a variety of deformation processes.Athinrubberlayerbetweentheceramicand composite improves multi-hit capability and a single layer of glass reinforced composite spall shield is bon- ded to the impact face of the ceramic to suppress forward spall generation and preserve the mechanical integrityofthearmor [1]. During projectile impact, stress wave propagation occurs through and between the diﬀerent layers of armor. The magnitude and the shape of propagating stresswavesdependontheacousticimpedanceofindi- vidual layers. In the initial few microseconds, a com- pressive wave is generated and propagates through the ceramic-facinglayerintheimpactdirection.Thiscom- pressive wave partly reﬂects back from the ceramic- composite interface to the ceramic layer as a tensile wave and the remaining part propagates through the composite backing plate and deforms it at relatively highstrainrates.Subsequentreﬂectionsfrominterfaces and free surfaces further complicate the wave propa- gationevents.FiniteElementAnalysis(FEA)modeling of these complex wave propagation events necessitates the utilization of high strain rate mechanical property data of the layer materials for more realistic calcula- tions. This study was, therefore, conducted to obtain high strain rate compressive mechanical property data  Corresponding author. Tel.: +90-232-498-6595; fax: +90- 232-498-6505. E-mail address: mustafaguden@iyte.edu.tr(M.Guden). 0142-9418/$-seefrontmatter # 2004ElsevierLtd.Allrightsreserved. doi:10.1016/j.polymertesting.2004.01.004