Modeling of Impact Properties of Auxetic Materials Phase 2
[Technical Report, Contract Report]
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This report presented work performed in phase 2 of a recent numerical investigation on impact properties of auxetic materials. In this phase of study, efforts were first taken to verify the results of the previous parametric studies. Through these verifications, a set of desired solution control parameters were established and demonstrated to produce reliable numerical solutions. These optimized solution control parameters were then applied in four different parametric studies to characterize the impact properties of the auxetic foam materials in different deformation ranges and under different impacter geometries. Upon completion of the parametric runs, the numerical solutions were first verified to ensure their numerical stability and then post-processed to generate the time histories of the desired physical variables, such as the impact force, the polymer internal energy and the total force transmitted to the substrates. These numerical solutions were found to be consistent with the previous analytical and experimental solutions and provided a good picture of the mechanical responses of these materials to impact loads. By examining these numerical results, some trends were discovered on the impact properties of the auxetic materials as a function of the material type, the unit cell geometry, the void fraction and the impact orientation.These trends provided useful guidelines for selecting auxetic foam materials to achieve optimalprotective performance in different applications.
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