STRENGTH SIZE EFFECT OF LAMINATED COMPOSITES

This paper presents results of theoretical and experimental analysis o f the effect of size on the strength of laminated composites. On the b asis of the suggested probabilistic analytical model of the composite, which is determined by sequential multi-step failure of single sublam inates, expressions for prediction of the random strength distribution and reliability are presented. The influence of the number of sublami nates (composite thickness) on general regularities of the strength si ze effect is shown, analyzed in detail, and explained. Experimental an alysis of the strength size effect is carried out on examples of carbo n-fiber-reinforced composites with lay-ups [0](n) at n = 10, 20, 40, 6 0, and [(0(2)/90 degrees)(s)](n) at n = 4 and 10, under uniaxial tensi on. Good agreement with the predicted mean values of the tensile stren gth is shown. Standardized tables of the mean statistical characterist ics of the laminated composite random strength in a plane stress state (mean value, coefficient of variation) are offered for practical engi neering applications.