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Experimental Determination of Fracture Toughness of Woven/Chopped Glass Fiber Hybrid Reinforced Thermoplastic Composite Laminates
  • A. Onur Ozdemir,
  • Cetin Karatas
A. Onur Ozdemir
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Cetin Karatas
Gazi Universitesi
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Abstract

Polymer composites have a wide share among engineering materials. It is important that the material properties are known before being used in industrial applications. Damage behavior needs to be determined in order to safely forming of laminated composites. Propagation characteristics of existing cracks for determining damage are among the current research topics of the researchers. In this study, the fracture toughness of the composite structure was investigated by performing compact tensile and compact compression tests for hybrid fiber reinforced polypropylene composite laminates which have three types of composition. The critical energy release rates of fiber and matrix in both tensile and compressive fracture cases were determined in pre-cracked specimens under plane-strain loading conditions. The damage mechanisms of the composite materials used in the present study were described as fiber breakage/buckling of longitudinal and matrix crack/crushing of transverse. As a result of the longitudinal tension, the damage progressed gradually as translaminar fiber breaking in materials containing continuous fibers. In case of the longitudinal compression, the damage occurred as fiber buckling in the material with higher continuous fiber content and intralaminar shearing in other specimens. In the transverse tension process, fiber-matrix separation caused intralaminar deformation in the materials. In the transverse compression process, the intralaminar matrix cracking brought about damage in the specimens. The highest fracture critical energy release rate was found in the material with maximal fiber layer.