Comparing Mode I, Mode II and Mixed-Mode I/II interlaminar fracture toughness of glass and carbon fiber reinforced polymer laminates with the same epoxy matrix system
Maria Gfrerrer, Veronika Koss, Johannes Wiener, Clara Schuecker, Andreas J. Brunner, Gerald Pinter
Abstract
• Quasi-static Mode I, II and I/II toughnesses are higher for GF- than for CF-epoxy. • GF- and CF-epoxy fracture toughness differs most for Mode II and least for Mode I. • Two Mixed-Mode I/II setups at 4:3 ratio are compared for GF- and CF-epoxy. • Fixed-Ratio Mixed-Mode and Mixed-Mode Bending tests yield comparable results. Quasi-static delamination resistance tests under Mode I, Mode II and Mixed-Mode I/II loading are performed on unidirectional (UD) glass fiber (GF) and carbon fiber (CF) reinforced polymer laminates manufactured with the same epoxy matrix. Compared to the CF-, the GF-epoxy laminate has a higher fracture toughness under all loading modes. Fracture toughnesses differ the most for Mode II and the least for Mode I loading. Mixed-Mode I/II fracture toughness is determined in Fixed-Ratio Mixed-Mode and Mixed-Mode Bending tests, performed at the same Mixed-Mode I/II ratio of 4:3. The two test methods yield comparable results for UD GF- and UD CF-epoxy.