報告題目：An Isogeometric Coupled Boundary Element Method and Finite Element Method for Structural-Acoustic Analysis through Loop Subdivision Surfaces

報告人：劉兆偉 (University of Glasgow)
報告時間：2018年9月7日（周五）上午10:00-11：00
報告地點：18-209會議室
主辦單位:國際合作處、科協、航空宇航學院、航空航天交叉研究院
報告摘要：

This present work proposes a novel approach for coupling finite element and boundary element formulations using a Loop subdivision surface discretisation to allow efficient acoustic scattering analysis over shell structures. The analysis of underwater structures has always been a challenge for engineers because it couples shell structural dynamics and acoustic scattering. In the present work, a finite element implementation of the Kirchhoff-Love formulation is used for shell structural dynamic analysis and the boundary element method is adopted to solve the Helmholtz equation for acoustic scattering analysis. The boundary element formulation is chosen as it can handle infinite domains without volumetric meshes.
     In the conventional engineering workflow, generating meshes of complex geometries to represent the underwater structures, e.g. submarines or torpedoes, is very time consuming and costly even if it is only a data conversion process. Isogeometric analysis (IGA) is a recently developed concept which aims to integrate computer aided design (CAD) and numerical analysis by using the same geometry model.    Non-uniform rational B-splines (NURBS), the most commonly used CAD technique, were considered in early IGA developments. However, NURBS have limitations when used in analysis because of their tensor-product nature. Subdivision surfaces discretisation is an alternative to overcome NURBS limitation. The new method adopts a triangular Loop subdivision surface discretisation for both geometry and analysis. The high order subdivision basis functions have C1 continuity, which satisfies the requirements of the Kirchhoff-Love formulation and are highly efficient for the acoustic field computations. The control meshes for the shell analysis and the acoustic analysis have the same resolution, which provides a fully integrated isogeometric approach for coupled structural-acoustic analysis of shells. The method is verified by the example of an acoustic plane wave which scatters over an elastic spherical shell. The ability of the presented method to handle complex geometries is also demonstrated.
報告人簡介：

Dr. Zhaowei Liu obtained his PhD degree from chair of computational mechanics in School of Engineering, University of Glasgow. During his PhD, he also worked as a short term research assistant at both the University of Nottingham and University of Glasgow. He is now undertaking a research associate role in the School of Engineering at the University of Glasgow. His research is focused on integrating Computer Aided Design (CAD) with novel numerical methods, more specifically, he is conducting research in the topic of isogeometric boundary element methods and its application to solid mechanics, acoustics, electromagnetics, computer aided design and shape optimization. He has published a number of papers including highly-rated journal: International Journal of Numerical Method in Engineering, Journal of Computational Physics etc.