Events

Engineering and Applied Sciences (EAS) PhD Thesis Defense by Ms. Rojin Ghandriz

Engineering and Applied Science PhD Thesis Defense by Ms. Rojin Ghandriz DATE: July 20, 2020 TIME: 10:00 a.m. – 12:00 p.m. LOCATION: Zoom Conference Link: https://umassd.zoom.us/j/97442528605 TOPIC: Computational Modeling of Anisotropic Fracture in 3D Printed Polymers and Patterned Structures ABSTRACT: 3D printing, or additive manufacturing (AM), has been transiting from demonstrative prototypes to functional products that are impacting a wide variety of sectors, from biomedical, electronic, and automotive to aerospace industries. However, the reduced fracture performance often observed in 3D printed parts limits their applications to end-use load-bearing components. The layered additive deposition process in 3D printing leads to anisotropic fracture behaviors and complicated crack propagation patterns, which brings challenges in computational modeling and analysis. In this study, both extended finite element method (XFEM) and phase field fracture method (PFFM) are developed to model anisotropic fractures in 3D printed polymers as well as patterned structures for enhanced fracture resistance. The XFEM with cohesive zone method (CZM) is first developed to model the inter-laminar fracture, cross-laminar fracture, and mixed inter-/cross-laminar fracture of 3D printed samples made of acrylonitrile-butadiene-styrene (ABS) materials with various build orientations. The model embeds anisotropic weak planes to capture kinked crack propagations and zig-zag crack paths observed in experiments. It is also applied to model anisotropic fracture in shales affected by bedding angles and sedimentary particles. Finally, an anisotropic PFFM formulation is developed to predict complicated crack deflections in 3D printed patterned structures coupled with material anisotropies. This study sheds light on predicting fracture in 3D printed materials and structures with optimal build and topology designs for enhanced performance. ADVISOR: Prof. Jun Li, Assistant Professor of Mechanical Engineering, UMassD COMMITTEE MEMBERS: · Prof. Wenzhen Huang, Professor, Chair of Department of Mechanical Engineering, UMassD · Prof. Caiwei Shen, Assistant Professor of Mechanical Engineering, UMassD · Prof. Alfa R Heryudono, Associate Professor of Mathematics, UMassD Open to the public. All EAS students are encouraged to attend. For more information, please contact Dr. Jun Li (jun.li@umassd.edu, 508-999-8692 ). Thank you, Sue Cunha, Administrative Assistant

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