ACKNOWLEDGEMENTS I would first and foremost like to thank my PH.D. supervisor, Dr. Jia Lu. He is brilliant as a teacher, mentor, and research collaborator, and provided incredible support to my research.I owe a lot to my wife Rong. Without her tremendous love, support, encouragement and sacrifice on her own career, I'd never be able to finish this work. I thank my parents and my bother, for their constant love and encouragement.A special thank is given to Dr. Timothy Marler, who provided me the soft armor models and the digital models of human body. A special thank is given to Dr.
ABSTRACTThis thesis aims to develop a design-oriented simulation approach for cloth analysis. Our approach is built on the framework of NURBS-based isogeometric analysis, which utilizes NURBS as the basis functions of analysis. NURBS is a class of parametric geometry to represent curves and surfaces in computer-aided design (CAD) programs. Recently, NURBS geometry has been used directly in analysis.The overall goal of this thesis is to develop a computation infrastructure that enables cloth analysis directly on NURBS geometry.The advantage of NURBS in the context of cloth modeling lies in the geometric smoothness. Using NURBS, it's easy to construct surfaces with C 1 or higher order of continuity. Compared to C 0 finite element geometry, the NURBS geometry is more effective in capturing wrinkles and folders of cloth, which are characteristics of cloth motion. The NURBS geometry enables the use of rotation-free Kirchhoff-Love shell. The rotation-free shell model not only saves freedoms, but also makes the contact/impact treatment much easier.The major contribution of this work is the development of a NURBS cloth modeling approach. The mechanical model of cloth and its implementation with NURBS geometry will be presented in detail. Proper constitutive laws are employed for fabric materials. Since NURBS geometry from CAD typically contains multiple patches and trimmed patches, a certain treatment is proposed so that geometry can be used directly in analysis.iii