20-Node Hexahedron Symplectic Elements for Stress Analysis of Composite Laminates
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摘要: 通常情况下,常规位移有限元法获得的应力结果比位移精度低一阶次,且面外应力难以满足连续性要求.联合最小势能原理和HR变分原理,构造出包含位移和3个面外应力两类变量的20节点六面体辛元.由于两类变量采用高阶插值函数近似,无需引入单元内部的非协调位移项,因此相关理论的推导过程非常简单.与Hamilton部分混合元不同,该辛元涉及的变量沿3个坐标方向均做离散处理,不受单元厚度和结构几何形状的限制.数值实例表明20节点辛元的数值结果收敛稳定.在粗糙网格的情况下,与20节点位移元相比,该文单元的面外应力更接近精确解.Abstract: Usually, the accuracy of the stresses obtained with the conventional displacement finite element method is one-order lower than that of the displacements, and the out-of-plane stresses can hardly meet the continuity requirements. Then, combined with the minimum potential energy principle and the H-R variational principle, a 20-node hexahedral symplectic element involving displacement and out-of-plane stress variables was established. Incompatible displacement terms are needless in the element since the 2 kinds of variables are approximated with higher-order interpolation functions. Hence, the derivation process of the theory is very simple. Unlike in the partially mixed Hamiltonian element, the variables involved in the symplectic element are discretized in 3 coordinate directions without restriction of the element thickness and the structure geometry. Numerical examples show that, the 20-node symplectic elements exhibit stable convergence. Under the coarse mesh, the out-of-plane stresses obtained with the proposed element are closer to the exact solution than those by the incompatible 8-node symplectic element.
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[1] REDDY J N. A simple higher-order theory for laminated composite plates[J]. Journal of Applied Mechanics,1984,51(4): 745-746. [2] NOOR A K, BURTON W S. Assessment of shear deformation theories for multilayered composite plates[J]. Applied Mechanics Reviews,1989,〖STHZ〗42(1): 1-13. [3] PIAN T H H, WU C C. Hybrid and Incompatible Finite Element Methods [M]. Chapman and Hall CRC, 2005. [4] JING H S, LIAO M L. Partial hybrid stress element for the analysis of thick laminated composite plates[J]. Computers & Structures,1990,36(1): 57-64. [5] 田宗漱, 卞学鐄. 多变量变分原理与多变量有限元方法[M]. 北京: 科学出版社, 2011.(TIAN Zhongshu, PIAN T H H. Variational Principle With Multi-Variables and Finite Element With Multi-Variables [M]. Beijing: Science Press, 2011.(in Chinese)) [6] REDDY J N, ROBBINS D H. Theories and computational models for composite laminates[J]. Applied Mechanics Reviews,1994,47(6): 147-169. [7] 钟万勰. 应用力学的辛数学方法[M]. 北京: 高等教育出版社, 2006.(ZHONG Wanxie. Symplectic Solution Methodology in Applied Mechanics [M]. Beijing: Higher Education Press, 2006.(in Chinese)) [8] 唐立民, 褚致中, 邹贵平, 等. 混合状态Hamilton元的半解析解和叠层板的计算[J]. 计算力学学报, 1992,9(4): 347-360.(TANG Limin, CHU Zhizhong, ZOU Guiping, et al. The semi-analytical solution of mixed state Hamilton element and the computation of laminated plates[J]. Chinese Journal of Computational Mechanics,1992,9(4): 347-360.(in Chinese)) [9] ZOU G P, TANG L M. A semi-analytical solution for laminated composite plates in Hamilton system[J]. Computer Methods in Applied Mechanics and Engineering,1995,128(3/4): 395-404. [10] QING G H, QIU J J, LIU Y H. Free vibration analysis of stiffened laminated plates[J]. International Journal of Solids and Structures,2006,43(6): 1357-1371. [11] ATLURI S N, GALLAGHER R H, ZIENKIEWICZ O C. Hybrid and Mixed Finite Element Methods [M]. Chichester: Wiley, 1983. [12] ARNOLD D N, FALK R S, WINTHER R. Mixed finite element methods for linear elasticity with weakly imposed symmetry[J]. Mathematics of Computation,2007,76: 1699-1724. [13] LIAO C L, TSAI J S. Partial mixed 3-D element for the analysis of thick laminated composite structures[J]. International Journal For Numerical Methods in Engineering,1992,35(7): 1521-1539. [14] QING G, TIAN J. Highly accurate symplectic element based on two variational principles[J]. Acta Mechanica Sinica,2018,34(1): 151-161. [15] 刘艳红, 李锐. 含参数辛元与热弹性复合材料层合板分析[J]. 复合材料学报, 2019,36(5): 1306-1312.(LIU Yanhong, LI Rui. Parametered symplectic element and analysis of thermoelastic composite laminates[J]. Acta Materiae Compositae Sinica,2019,36(5): 1306-1312.(in Chinese)) [16] PAGANO N. Exact solutionsfor composite laminates in cylindrical bending[J]. Journal of Composite Materials,1969,3(3): 398-411. [17] 范家让. 强厚叠层板壳的精确理论[M]. 北京: 科学出版社, 1996.(FAN Jiarang. Exact Theory of Laminated Thick Plates and Shells [M]. Beijing: Science Press, 1996.(in Chinese))
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