Experimental investigation and hierarchical modeling of FRP materials for automobile application

High performance FRP composites have been widely used in aerospace industry due to their outstanding performance and high strength-to-weight ratio. Recently, there is an increasing interest in these materials for their potential applications in other transportation, such as automotive, industry. However, the behaviors of the materials are not fully understood, and modeling of the materials is difficult due to the complicated mesostructure. In this dissertation, combined experimental and numerical investigation is presented to capture and predict their special behaviors. Automatic modeling tools are established to help to predict and optimize the performances of FRP materials.; In the part of experimental investigation, comprehensive tests have been conducted for the textile composites and structures. Due to existence of microstructures, the behaviors of textile composites are mechanism-dominant, especially after damage occurs. Special attentions are devoted to identify these mechanisms for braided composite material and structures through large number of tube crash tests.; Woven and braided composites are two of the most widely used textile composites. The microscale reinforcements of textile composites contribute to the outstanding performance of textile composites and provide tailorability for the material properties, but at the same time, they become obstacles for numerical analysis. In this research, a novel model for fiber yarns is presented based on the understanding of special behaviors of fiber bundles. An iterative predictor-multicorrector algorithm is provided to predict the mechanical equilibrium between contacting yarns. A meshing scheme is developed, and homogenization method is utilized to make multi-scale analysis. As a result of these efforts, a system of automatic modeling methods is established for woven composites. Similarly, another system of automatic modeling tools for braided composites is developed. These methods will be meaningful to aid in the design of textile composites.; Homogenization method is the basis of the hierarchical model in this research. The theory is comprehended from the view point of general global-local analytical methodology. This general understanding will enable us to extend the theory to wider range of problems. An initial attempt is introduced to develop global-local model for composite shell structures.; Another advantage of FRP textile composites is the improved damage performance. A damage modeling method is derived based on the general framework of nonlinear homogenization method.; In addition, numerical results are presented for each part to demonstrate the performance of proposed models and algorithms.