关键词:S-R和分解;三维无网格法;几何非线性 Abstract Due to its overcoming the deficiencies of classic finite deformation theories, Strain-Rotation (S-R) decomposition theorem can provide a reliable theoretical support for the geometrically nonlinear simulation. In addition, due to it’s independent of the elements and meshes, the element-free method has more advantages to solve large deformation problems compared to finite element method (FEM), so that the accuracy is guaranteed as a result of avoiding the element distortions. Therefore, a more reasonable and reliable geometric nonlinearity numerical method certainly will be established by combining the S-R decomposition theorem and element-free method. But the studies of element-free methods based on S-R decomposition theorem in current literature are limited to two-dimensional problems. In most cases, three-dimensional mathematical-physical models must be established for the practical problems. Therefore it is very necessary to establish a three-dimensional element-free method based on the S-R decomposition theorem. Present study extends the previously work by authors into three-dimensional case: The incremental variation equation is derived from updated co-moving coordinate formulation and principle of potential energy rate in this paper, and three-dimensional discretization equations are obtained by element-free Galerkin method (EFG). By using the MATLAB programs based on the proposed 3D S-R element-free method in present study, the nonlinear bending problems for three-dimensional cantilever beam and simply supported plates subjected to uniform load are numerical discussed. The reasonability, availability and accuracy of 3D S-R element-free method proposed by present paper are verified through comparison studies, and the numerical method in present work can provide a reliable way to analysis 3D geometric nonlinearity problems.
显示原图|下载原图ZIP|生成PPT 图6平板中面中点挠度与载荷关系(各向同性板). -->Fig.6The central deflection of rectangle plate’s mid-plane versus load (isotropic plate) -->
同样以图5为例, 若板为正交各向异性材料, 杨氏模量有 MPa, MPa, 剪切模量有 MPa, 泊松比 , 其长宽高满足 mm, mm. 图7给出该算例的平板中面中点的无量纲挠度与无量纲均布载荷强度之间的关系. 同样可以发现当节点数为 时, 计算结果就已经收敛. 这里还可以发现, 对于正交各向异性板, 本文方法的计算结果是大于Shen[38] 给出的结果, 这是与前文的各向同性板算例不一样的. 相对于Zaghoul 等[42] 给出的经典解(CPT) 和Shen[38] 的结果, 本文的三维S-R 无网格法计算结果与Zaghoul[42] 给出的实验值最接近. 因此充分说明了本文三维S-R无网格法的准确性, 也说明了S-R 和分解理论相对于其它有限变形理论的优越性. 显示原图|下载原图ZIP|生成PPT 图7平板中点挠度与载荷的关系(正交各向异性板). -->Fig.7The central deflection of rectangle plate’s mid-plane versus load (orthotropic plate) -->
5 结 论
本文将基于S-R和分解定理的二维无网格数值方法扩展到三维情况, 给出了3D-SR-EFG数值计算方法, 并通过对梁、板结构的非线性弯曲问题典型算例进行了对比分析, 验证了该方法在求解三维几何非线性问题时的合理性、有效性和准确性. 另外, 对于本文提出的方法在与其他方法进行对比时所表现出来的一些差异性, 也给出了合理的解释. 在受均布载荷的四边简支正交各向异性方形板的算例中, 本文提出的数值计算方法是在所有对比方法中最接近实验结果的一种方法, 说明了3D-SR-EFG方法可以作为一种更加可靠的几何非线性数值计算方法. The authors have declared that no competing interests exist.
(ShaoYulong, DuanQinglin, GaoXin, et al.Adaptive consistent high order element-free Galerkin method .Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(1): 105-116 (in Chinese)) [本文引用: 1]
(YangJianjun, ZhengJianlong.Meshless local strong-weak (MLSW) method for irregular domain problems .Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(3): 659-666 (in Chinese)) [本文引用: 1]
[8]
ChenJS, PanC, WuCT, et al.Reproducing Kernel particle methods for large deformation analysis of non-linear structures .Computer Methods in Applied Mechanics & Engineering, 1996, 139(1-4): 195-227 [本文引用: 1]
[9]
LiS, HaoW, LiuWK.Numerical simulations of large deformation of thin shell structures using meshfree methods .Computational Mechanics, 2000, 25(2-3): 102-116 [本文引用: 1]
[10]
LiewKM, NgTY, WuYC.Meshfree method for large deformation analysis-a reproducing kernel particle approach .Engineering Structures, 2002, 24(5): 543-551 [本文引用: 1]
[11]
ZhangLW, SongZG, LiewKM.Nonlinear bending analysis of FG-CNT reinforced composite thick plates resting on Pasternak foundations using the element-free IMLS-Ritz method .Composite Structures, 2015, 128: 165-175 [本文引用: 1]
[12]
DoVNV, LeeCH.Bending analyses of FG-CNTRC plates using the modified mesh-free radial point interpolation method based on the higher-order shear deformation theory .Composite Structures, 2017, 168: 485-497 [本文引用: 1]
(ChenZhida.Geometric field theory of finite deformation mechanics for continuum .Chinese Journal of Theoretical and Applied Mechanics, 1979, 15(2): 107-117 (in Chinese)) [本文引用: 1]
(ChenZhida.Geometric field theory of finite deformation mechanics for continuum (continued)(elastic finite deformation energy principle) .Journal of Tsinghua University (Science and Technology), 1979, 19: 45-57 (in Chinese)) [本文引用: 1]
[17]
ChenM, LiangJ, ChenX, et al.On uniqueness, existence and objectivity of S-R decomposition theorem .Applied Mathematics and Mechanics (English Edition), 1997, 18(9): 817-823 [本文引用: 1]
(ChenZhida.Increment method of Finite deformation and rotational computing in continuum mechanics .Applied Mathematics and Mechanics, 1997, 18(9): 817-823 (in Chinese)) [本文引用: 1]
(QinZhong. Nonlinear finite element and its applications based on new large deformation thoery. [PhD Thesis]. Beijing: China University of Mining and Technology (Beijing), 1986 (in Chinese)) [本文引用: 1]
(ShangYong. The theory and finite element analysis of the elastoplasticity large deformation problem with contact friction boundary. [PhD Thesis]. Beijing: China University of Mining and Technology (Beijing), 1987 (in Chinese)) [本文引用: 1]
(ShangYong, ChenZhida.Large deformation problem of rubber ring compressed in diameter direction .Journal of Computational Structural Mechanics and Applications, 1989, 6(4): 13-20 (in Chinese)) [本文引用: 1]
(ShangYong, ChenZhida.On large deformation unilateral contact problem with friction(I)-Incremental variational equation .Applied Mathematics and Mechanics, 1989, 10(12): 1049-1058 (in Chinese)) [本文引用: 1]
(ShangYong, ChenZhida.On large deformation unilateral contact problem with friction(II)-nonlinear finite element technique and its application .Applied Mathematics and Mechanics, 1990, 11(1): 1-11 (in Chinese)) [本文引用: 1]
(LiPing. The updated co-moving coordinate formulation for the nonlinear lager deformation finite element analysis and application. [PhD Thesis]. Beijing: China University of Mining and Technology (Beijing), 1991 (in Chinese)) [本文引用: 1]
[25]
LiP, ChenZD.The updated co-moving coordinate formulation of continuum mechanics based on the SR decomposition theorem .Computer Methods in Applied Mechanics and Engineering, 1994, 114(1-2): 21-34 [本文引用: 4]
(GaoLitang, LiXiaodong, ChenLigang, et al.Thermal-elastic-plastic finite element analysis of reinforced slabs under fire-based on S-R decomposition theorem(II: Analysis of examples) .Acta Mechanica Solida Sinica, 2006, 27: 138-142 (in Chinese)) [本文引用: 1]
(GaoLitang, SongYupu, DongYuli.Thermal-elastic-plastic finite element analysis of reinforced slabs under fire-based on S-R decomposition theorem(I: Theories) .Chinese Journal of Computational Mechanics, 2007, 24(1): 86-90 (in Chinese)) [本文引用: 1]
(HeManchao, GuoHongyun, ChenXin, et al.Numerical simulation analysis of large deformation of deep soft rock engineering based on solar decomposition theorem .Chinese Journal of Rock Mechanics and Engineering, 2010, 29(s2): 4050-4055 (in Chinese)) [本文引用: 1]
(XieHeping, ChenZhida.The boundary element method of nolinear large deformation .Journal of China University of Mining & Technology, 1986(4): 101-109 (in Chinese)) [本文引用: 1]
(XieHeping.Analysis of nonlinear large deformation problems by boundary element method .Applied Mathematics and Mechanics, 1988, 9(12): 1087-1096 (in Chinese)) [本文引用: 1]
[31]
GaoY, FengG, YeungMCR.Modification of discontinuous deformation analysis method based on finite deformation theory .Chinese Journal of Rock Mechanics and Engineering, 2011, 30(11): 2360-2365 [本文引用: 1]
(LuoDan.Based on S-R decomposition theorem analysis of element free Galerkin method on geometric nonlinear problems. [Master Thesis]. Changsha: Hunan University, 2011 (in Chinese)) [本文引用: 5]
(ChenFangzu, LuoDan.Element free Galerkin method for geometrically nonlinear problems based on the S-R decomposition theorem .Journal of Hunan Unviersity (Natural Sciences), 2012, 39(1): 42-46 (in Chinese)) [本文引用: 2]
(SongYanqi, HaoLiangjun, LiXiangshang.Numerical analysis geometrically nonlinear problems based on The S-R decompostion theorem .Applied Mathematics and Mechanics, 2017, 38(9): 1029-1040 (in Chinese)) [本文引用: 3]
[35]
FanH, ZhengH, ZhaoJ.Discontinuous deformation analysis based on strain-rotation decomposition .International Journal of Rock Mechanics & Mining Sciences, 2017, 92: 19-29 [本文引用: 2]
[36]
FanH, ZhengH, ZhaoJ.Three-dimensional discontinuous deformation analysis based on strain-rotation decomposition .Computers & Geotechnics, 2018, 95: 191-210 [本文引用: 3]
[37]
BatheKJ, RammE, WilsonEL.Finite element formulations for large deformation dynamic analysis .International Journal for Numerical Methods in Engineering, 2010, 9(2): 353-386 [本文引用: 2]
[38]
ShenHS.Large deflection of composite laminated plates under transverse and in-plane loads and resting on elastic foundations .Composite Structures, 1999, 45(2): 115-123 [本文引用: 8]
[39]
LevyS.Bending of rectangular plates with large deflections. NACA Tech, Note No. 846, 1942 [本文引用: 6]
[40]
GorjiM.On large deflection of symmetric composite plates under static loading .Journal of Mechanical Engineering Science, 1986, 200(1): 13-19 [本文引用: 6]
(LiuRenhuai, XueJianghong.Development of nonlinear mechanics for laminated composite .Chinese Journal of Theoretical and Applied Mechanics, 2017, 49(3): 487-506 (in Chinese)) [本文引用: 1]
[42]
ZaghloulSA, KennedyJB.Nonlinear behavior of symmetrically laminated plates .Journal of Applied Mechanics, 1975, 42(1): 234-236 [本文引用: 2]