Stacking sequence effect on tensile and fatigue strength of symmetric laminates
This paper presents the results of an experimental investigattion into the tensile monotonic and fatigue behaviour of symmetric fibreglass-epoxy coupons using three ply angle orientations, 45°, -45° and 0° which were interchanged in three different configurations: [45 2 , -45 2 , O 2 ] s , [45 2 , O 2 , -45 2 ] s and [O 2 , 45 2 , -45 2 ] s .The results show that there is significant sequcnce effect on the monotonic strength and the fatigue performance. The monotonic results demonstrate an incrcease of 11% in the strength and 6% in stiffness between the weakest laminate, [O 2 , 45 2 , -45 2 ] s , and the strongest laminate, [45 2 , -45 2 , O 2 ] s . The fatigue performance depends on lay-up and stress level. At higher stresses, the trend in stacking sequence effect on fatigue strength is the same as for monotonic loading. In contrast, at lower stresses the trend is opposite. The sequence effect observed in the monotonic and fatigue loading is discussed subsequently based on the numerical analysis of interlaminar stresses induced by the free-edge and constraint effect of 0° ply on damage development