MULTI-SCALE MEASUREMENT OF TENSILE BEHAVIOR OF GLASS FIBER COMPOSITES AT HIGH STRAIN RATE: FIBER FRAGMENTATION IN EPOXY RESIN

摘要

High strength and light weight composite materials used in various structural components of aviation and automotive applications deform under high rate loading conditions during collision. Since composite that contain continuous fibers consisted of structures at multiple scales (e.g. from single fibers to laminates), the fracture process must be characterized at these multiple scales to connect fracture mechanism among the properties of the constituents with those of the composite structure. Usually, the mechanical properties of composites (such as strength, failure strain and toughness) are measured under quasi-static loading conditions to characterize failure mechanism of composites. In this study, we investigate loading rate effects on the glass fiber break process in an epoxy matrix considering a multi-scale measurement approach (i.e. from single fiber to laminates). First, we fabricate model composites using a single fiber array, which is the fundamental structure of composites, and then load the specimen in tension to monitor the fiber break process at quasi-static loading and high rate loading respectively. Statistical and micro mechanical characterization methods are used to analyze the fiber break process and fiber-fiber interactions in epoxy matrix as a function of loading rates.