25% 12.5% 50% 12.5% 9o°ply fracture ±45°ply fracture (resin) (resin) Cracks at o°(resin) Delamination;deformation around the hole Figure 6.1 Cracks in a Laminate with Hole when Load Increases G 01 metal laminated (90) plasticized zone (0月 Figure 6.2 Stress Concentration Factors with the maximum stress o in the laminate given as: where E and E,are the moduli of elasticity in the 0 and 90 directions Gsy is the shear modulus Vy is the Poisson ratio 2003 by CRC Press LLCwith the maximum stress s¢ M in the laminate given as: where Ex and Ey are the moduli of elasticity in the 0∞ and 90∞ directions Gxy is the shear modulus nxy is the Poisson ratio Figure 6.1 Cracks in a Laminate with Hole when Load Increases Figure 6.2 Stress Concentration Factors sM¢ s ¢ 1 2 Ex Ey ----- – nxy Ë ¯ Ê ˆ Ex Gxy + + -------- Ó ˛ Ì ˝ Ï ¸ = ¥ © 2003 by CRC Press LLC