Size effects on the bending strength of fiber-reinforced polymer matrix composites

This article investigates the size effects associated with length and width, on the bending strength of marine grade polymer matrix laminated composites. A new expression for predicting the strength size effect was developed and was verified using both laboratory testing and probabilistic finite element analysis (FEA). Woven [0/45/—45/0]5sf E-glass/vinyl ester material specimens with different lengths and widths and same thickness were evaluated to predict the effect of specimen size on the bending strength. In the probabilistic FEA models, elastic properties (E11, E22, G12, υ12), and strength parameters (F1t, F1c, F2t , F2c, F6, ε1t, ε 1c, ε2t, ε2c, ε12) of the woven fabric E-glass/vinyl ester ASTM D6272 coupons were considered as random fields, and generated using Monte Carlo simulations. The relationship between the bending strength and specimen size of the [0/45/—45/0]5sf lay-up was also evaluated experimentally. Thirty-two material specimens were prepared and tested according to ASTM D6272 using combinations of two span-to-thickness ratios (32 : 1 and 16 : 1), and two width-to-thickness ratios (3 : 1 and 1.5 : 1).