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Description: TITLE: Computational Modeling of Fracture in 3D Printed Polymers and Structures
ABSTRACT: Additive manufacturing, or 3D printing, is coming of age as a viable advanced manufacturing technology that is already impacting a wide variety of sectors, from biomedical, electronics, automotive to aerospace industries. However, the reduced fracture resistance often observed in 3D printed materials limits its application to functional load-bearing components. The fracture of 3D printed polymers with various build orientations and structural patterns are studied using the extended finite element method (XFEM) and phase field fracture method (PFFM), respectively. The XFEM with cohesive zone method (CZM) is employed to model the inter-laminar fracture (fracture between layers), cross-laminar fracture (fracture through layers), as well as mixed inter-/cross- laminar fracture of 3D printed samples made of acrylonitrile-butadiene-styrene (ABS) materials. Both elastic and elastic-plastic fracture models are developed for the inter-laminar and cross-laminar fracture, respectively. For mixed inter-/cross- laminar fracture, an anisotropic cohesive damage model is developed to predict the kinked crack propagations. The computational models successfully captured different fracture behaviors under different build orientations. Furthermore, 3D printed structures using designated surface patterns as an alternative way to enhance fracture resistance is studied. The PFFM is used to robustly predict the complicated crack deflections in 3D printed structures with patterned surfaces. In the future, more efficient schemes for PFFM will be developed to save computational costs. Based on PFFM simulations, the optimization of build orientations and surface patterns will be studied to enhance fracture resistance of 3D printed polymers and structures.