Low Velocity Impact Behavior and Modeling of Loose-Knit Polymer Composite Materials

Abstract An investigation into knitted reinforced polymer composites was performed with emphasis on the impact behavior associated with this material type. Overviews of knitting terminology and some applications available for knitted reinforced polymer composites are presented. Impact performance characteristics are examined with emphasis on testing and evaluation techniques available. Large deformation behavior was observed in testing and modeling areas with elastomeric polymer materials being the main subject of discussion. This allowed the knitted fabric reinforcement to be taken advantage of in these "flexible composites."An impact test rig was created in order to analyze the performance of two different types of knitted reinforced polymer composite material, with emphasis on a commercially available product due to its availability. The test setup will be discussed in great detail and will be based on designs found in the literature. Post impact analysis will be performed based on techniques outlined in the literature with examination of the permanent deformation and energy absorbing capabilities of the materials tested.Through an industrial partnership program, a large scale finite element model was created in order to examine the wind uplift performance of a commercial roofing application. This model will be created in a multi-level fashion from micro-scale to macro-scale in order to examine the effects each of the constituents has on the overall performance of the composite membrane. Material property testing and curve fit capabilities will be employed in order to create the material models used in the finite element simulations. Comparisons between experimental tests and simulation results will show good agreement between the two, allowing for validation in potential usage of the model for predictive based purposes in order to provide recommendations for best changes to the material to explore further.