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Multi-Scale Computational Modeling of Short Fiber Reinforced Thermoplastics



Short-fiber reinforced polymer (SFRP) composites usually consist of particles that are slender, relatively short compared to the overall dimensions of the part, and imperfectly distributed in a continuous-phase matrix. Although not as stiff or as strong as their continuous counterpart, they have several attractive characteristics. In fact, their capability of being manufactured in complex geometries to conform to the desired shape without being damaged or distorted, their isotropic behavior, and their low fabrication costs are enough to make short-fiber reinforced composites the material of choice. Multi-scale modeling with de-homogenized approach is employed to consider the effect of fiber length increase and its associated manufacturing defects. Commonly used structural design software have difficulties predicting manufacturing parameters and constituent properties of short or long fiber reinforced polymer composites to meet mandated design requirements. A computational method is introduced for the virtual simulation of performance of chopped fibers in polymer composites. This new approach did lead to the development of a specialized multiscale material characterization of composite system comprising of: a) chopped fiber material modeling based on nano-mechanics failure theory considering fibers as inclusion, b) micro-macro mechanics, and damage failure theory, and c) structural durability and damage tolerance (D&DT) analysis under crush service loading. The material model established in MCQ-Chopped is integrated/coupled with FEA using GENOA platform software to perform multi-scale progressive failure analysis (MSPFA). The tensile properties and compressive properties of chopped tape thermoplastic composite were investigated by test and show saturation of mechanical properties. The fiber length shows different effect on each mechanical property which is consistent with computational material modeling results. Predictive software also indicated that as fiber length increased the contribution of failure mechanisms changed. Sensitivity analysis of mechanical response considering defects and fiber waviness are performed to design material with better performance.

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