Design of Pseudoductile Unidirectional Hybrid Composites Based on the Model of a Dry Bundle

An analytical method for designing layered high-modulus and high-strength fibrous hybrid composite materials with a highly nonlinear mechanical behavior is put forward. The elastic and strength characteristics of unidirectional layers of the composites were determined experimentally. Then, the parameters of Weibull distribution of the strength of carbon and glass fibers were estimated using test results for specimens of hybrid structure with a preliminary calculated number of carbon plastic layers in the composite. Using the criterion of maximum structural strength with a restricted elastic modulus and proportionality limit, the structure of a hybrid composite with thin CFRP and GFRP layers is optimized. A kinematic loading of a hybrid composite in which all layers deform together without stratification is considered. The Daniels model of dry bundle, with account of Weibull distribution of fiber strength, is employed to consider the decrease in the stiffness of composite layers and of the composite as a whole caused by microdefects. The approach offered was used in the design of a pseudoductile hybrid carbon/glass plastic with the highest structural strength. It was found that m approximate to 0.30, which agreed with experimental data.