EXPERIMENTAL AND NUMERICAL INVESTIGATION ON THE FRACTURING BEHAVIOR AND SCALING OF DISCONTINUOUS FIBER COMPOSITE STRUCTURES

Abstract

Discontinuous fiber composites (DFCs) have received significant attention from many industries due to their unique advantages in manufacturing capabilities. Compare to the continuous fiber composites, DFCs can be formed into complex contours. Also, they are optimized to be used for the compression molding process which is a suitable manufacturing method for high volume production. DFCs possess these manufacturing capabilities because of their unique meso-structures. They are composed of randomly oriented, and deposited platelets or chips made of prepregs. Because they contain fiber volume fractions similar to their pristine prepregs, they possess similar stiffness compared to the quasi-isotropic laminate made of identical prepregs. They are a suitable material form to be used for complex shapes yet stiff and lightweight structures.Despite their strong manufacturing advantages, engineers and designers do not fully appreciate DFCs' capabilities. The main reason is that DFCs possess strong stochastic fracturing behaviors. The complex mechanisms make DFCs far more difficult to analyze and predict their mechanical responses compare to the continuous fiber composites. As a result, many industries are heavily relied on costly physical tests. The physical experiment should only be proceeded when it is necessary. Also, they only provide insights to the meso-structures that they tested. Therefore, computational models based on the experimental data must be established in order to expand the applications of DFCs. In this study, we analyze the fracturing behaviors of DFCs and develop computational tools to understand the failure mechanisms. We experimentally investigate and numerically analyze the unique relationship between the meso-structures and macro-scale material behaviors. We focus on the tensile behaviors of DFCs with and without notches. We study various meso-structures composed of different platelet sizes and structural thicknesses. By leveraging the computational tools validated against the experiment, we can create safer and more efficient design guidelines to broaden the applications of DFCs.