共查询到20条相似文献,搜索用时 15 毫秒
1.
《Comptes Rendus de l'Académie des Sciences》2000,328(11):785-791
We suggest an energetic fracture parameter for non elastic materials. This one is presented in a domain integral, and founded on the release rate of the total mechanical energy received by a notched solid, using a domain derivation method. This parameter is proposed for a large class of loading and materials described by internal variables. It is shown that this parameter is reduced to the Rice–Cherepanov integral when the material is either elastic or elastoplastic and submitted to proportional loading. 相似文献
2.
A direct domain/boundary element method (D/BEM) for the dynamicanalysis of elastoplastic thick plates resting on Winkler-typefoundation is presented. The formulation presented includes the effectsof shear deformation and rotatory inertia following Reissner–Mindlin'sdeformation theory assumption. The method employs the elastostaticfundamental solution of the problem resulting in both boundary anddomain integrals due to inertia, plasticity and foundation pressureterms. By discretizing the integral equations and integrating theresulting matrix equation of motion by an explicit time integrationscheme the history of the plate dynamic response can be obtained.Applications are shown for impacted elastoplastic Reissner–Mindlinplates with smooth boundaries on several different foundations. 相似文献
3.
考虑膨胀力的非饱和介质热-水-应力耦合二维有限元分析 总被引:3,自引:0,他引:3
从建立应力平衡方程、水连续性方程、能量守恒方程和弹塑性矩阵入手,使用Galerk in方法,将各控制方程分别在空间域和时间域进行离散,开发出了一个可考虑膨胀力的用于分析非饱和介质中热-水-应力耦合弹塑性问题的二维有限元程序.通过对一个假定的核废料地下处置库的热-水-应力耦合问题的数值计算,比较了无、有膨胀力时的情况,在定性上验证了该程序的正确性. 相似文献
4.
《International Journal of Solids and Structures》2005,42(16-17):4588-4612
This paper presents a numerical method for modeling the micromechanical behavior and macroscopic properties of fiber-reinforced composites and perforated materials. The material is modeled by a finite rectangular domain containing multiple circular holes and elastic inclusions. The rectangular domain is assumed to be embedded within a larger circular domain with fictitious boundary loading represented by truncated Fourier series. The analytical solution for the complementary problem of a circular domain containing holes and inclusions is obtained by using a combination of the series expansion technique with a direct boundary integral method. The boundary conditions on the physical external boundary are satisfied by adopting an overspecification technique based on a least squares approximation. All of the integrals arising in the method can be evaluated analytically. As a result, the elastic fields and effective properties can be expressed explicitly in terms of the coefficients in the series expansions. Several numerical experiments are conducted to verify the accuracy and efficiency of the numerical method and to demonstrate its application in determination of the macroscopic properties of composite materials. 相似文献
5.
Hongjun Yu Linzhi Wu Licheng Guo Shanyi Du Qilin He 《International Journal of Solids and Structures》2009,46(20):3710-3724
An interaction (energy) integral is derived for the computation of mixed-mode stress intensity factors (SIFs) in nonhomogeneous materials with continuous or discontinuous properties. This method is based on a conservation integral that relies on two admissible mechanical states (actual and auxiliary fields). In general, the interaction energy contour integral is converted into an equivalent domain integral in numerical computations. It can be seen from the equivalent domain integral, the integrand does not involve any derivatives of material properties. Moreover, the formulation can be proved valid even when the integral domain contains material interfaces. Therefore, it is not necessary to limit the material properties to be continuous for the present method. Due to these advantages the application range of the interaction integral method can be greatly enlarged. The numerical implementation of the derived expression is combined with the extended finite element method (XFEM). Using this method, the influences of material properties on the mixed-mode SIFs are investigated for four types of material properties selected in this work. Numerical results show that the mechanical properties and their first-order derivatives can affect mode I and II SIFs greatly, while the higher-order derivatives affect the SIFs very slightly. 相似文献
6.
This paper presents a new strategy of using the radial integration boundary element method (RIBEM) to solve non-homogeneous heat conduction and thermoelasticity problems. In the method, the evaluation of the radial in-tegral which is used to transform domain integrals to equivalent boundary integrals is carried out on the basis of elemental nodes. As a result, the computational time spent in evaluating domain integrals can be saved considerably in comparison with the conventional RIBEM. Three numerical examples are given to demonstrate the correctness and computational efficiency of the proposed approach. 相似文献
7.
D. Soares 《International Journal of Solids and Structures》2008,45(16):4474-4483
This study presents a hybrid BEM–FEM procedure for the dynamic analysis of elastoplastic models. In this hybrid approach, boundary node and internal point displacements are evaluated considering the time-domain BEM formulation (initial stress approach), and stresses are computed taking into account FEM techniques (domain discretization is only necessary where non-linear behaviour is expected to occur). This hybrid methodology is very appropriate to model infinite or semi-infinite elastoplastic models and, at the end of the paper, three numerical applications are presented, illustrating the potentialities of the proposed formulation. 相似文献
8.
Problems associated with finite element simulation of the forming processes are characterized by large elastoplastic deformations, evolutive contact with friction, geometrical nonlinearities inducing a severe distortion of the computational mesh of the domain. In this case, frequent remeshing of the deformed domain during computation are necessary to obtain an accurate solution and complete the computation until the termination of the numerical simulation process. This Note presents a new adaptive remeshing method of thin sheets for numerical simulation of metal forming processes. The proposed method is based on geometrical criteria and does not use the geometry of the forming tools. It is integrated in a computational environment using the ABAQUS solver. Numerical examples are given to show the efficiency of our approach. To cite this article: L. Moreau et al., C. R. Mecanique 333 (2005). 相似文献
9.
This paper systematically deals with the following three problems: (1) Some numerical schemes in coupling FEM- and BEM: including condensation of the boundary integral equation, symmetrization of equivalent stiffness matrix and treatment of traction discontinuity, (2) Coupling of elastoplastic finite elements to elastic boundary elements, (3) Coupling of elasto-viscoplastic finite elements to elastic boundary elements and numerical stability condition. 相似文献
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求解饱和半空间上弹性圆板固结沉降的积分方程 总被引:1,自引:0,他引:1
本文采用解析方法分析了弹性圆板在饮和半空间上的固结沉降。考虑弹性圆板与饮和半空间的接触面上无摩擦力,且饱和半空间表面为全部透水的。运用Biot固结理论和积分方程技术,在Laplace变换域上建立了弹性圆板固结沉降的对偶积分方程,并化此对偶积分方程为第二类Fredholm积分方程。通过对其核函数的有效数值发得到第二类Fredholm积分方程的解,再利用Lapace反演技术获得弹性板在时间域中的固结沉 相似文献
14.
一类非线性奇异积分方程及其数值方法研究 总被引:1,自引:0,他引:1
探讨了一类非线性奇异积分方程的数理性质以及在颗粒雷诺数Rep<1时此类方程解的存在条件,然后详细研究了该方程的数值计算方法并构造称之为P(EC)^k多步法的差分格式,分析了该格式的收敛性和代数精度,得到时域离散步长的约束关系。运用该格式计算了静止流场和均匀振荡流中球形小颗粒的非恒定运动,将计算结果与其解析解及有关实验数据的比较表明,上述数值方法具有良好的计算精度。 相似文献
15.
Terumi Touhei Taku Kiuchi Kentaro Iwasaki 《International Journal of Solids and Structures》2009,46(21):3860-3872
A fast method for solving the volume integral equation is introduced for the solution of forward and inverse multiple scattering problems in an elastic 3-D full space. For both forward and inverse scattering analysis, the volume integral equation in the wavenumber domain is used. By means of the discrete Fourier transform, the volume integral equation in the wavenumber domain can be dealt with as a Fredholm equation of the 2nd kind with respect to a non-Hermitian operator on a finite dimensional vector space. The Bi-CGSTAB method is employed to construct the Krylov subspace in the wavenumber domain. The current procedure establishes a fast and simplified method without requiring the derivation of a coefficient matrix. Several numerical results validate the accuracy and effectiveness of the current method for both forward and inverse scattering analysis. According to the numerical results, the reconstruction of inhomogeneities of the wave field is successful, even for multiple scattering of several cubes. 相似文献
16.
In this study, a procedure for calculating the generalized stress intensity factor (GSIF) for 2D sliding complete contacts is presented. The method is based on a domain integral equivalent to a path-independent integral. The domain character of the approach makes it very suitable for the post-processing of finite element solutions. The robustness and accuracy of the method are assessed through numerical examples, comparing the obtained results with other techniques, such as stress extrapolation and the path-independent contour integral. In addition, the multiplier constants for other terms in the expansion series are also computed. 相似文献
17.
A. A. Artem’eva V. G. Bazhenov D. V. Zhegalov D. A. Kazakov E. V. Nagornykh 《Journal of Applied Mechanics and Technical Physics》2015,56(6):951-958
A method of the numerical solution of nonlinear unsteady problems of axisymmetric elastoplastic straining of shells of revolution with allowance for torque loading at high strains is proposed. The method is based on the geometrically nonlinear theory of the Timoshenko shells and the plasticity theory with due allowance for combined isotropic and kinematic hardening. The problem is solved with the use of the variational difference method. Results of numerical and experimental investigations of elastoplastic straining of cylindrical shells under proportional and sequential kinematic tensile and torque loading are reported. 相似文献
18.
A method for solving boundary-value problems of plasticity with allowance for the stress mode is developed. To describe the
elastoplastic deformation of an isotropic material, use is made of constitutive equations that include two nonlinear functions
dependent on the stress mode and determined experimentally. The elastoplastic state of a thin cylindrical shell under axisymmetric
loading is calculated as a numerical example. The numerical results demonstrate good convergence of the method. The effect
of the stress mode on the strain distribution in a cylindrical shell is assessed 相似文献
19.
具有有限差分法特征的虚单元法,可视为是有限元法向任意多边形单元的扩展。在材料细观力学性能表征、非均质材料力学分析等非线性问题方面,传统的弹塑性有限元法具有网格数目多、效率低下等不足之处,而虚单元法使网格划分更加灵活,为材料的弹塑性力学分析等非线性问题提供了新的思路。基于增量法弹塑性力学原理和双线性投影算子,建立了弹塑性力学问题的虚单元法求解技术,提出了弹塑性力学问题虚单元法的应力更新方案,研究了弹性力学问题虚单元法的精度和收敛性,讨论了虚单元法求解弹塑性力学问题的网格依赖性。同时,开展了任意多边形和凹多边形单元的数值试验研究,结果表明,虚单元法无须分割多边形,仅需节点自由度便可求得单元刚度矩阵和应力等效荷载,程序实现简单,计算精度高,改善了传统有限元的网格依赖性和塑性区的网格奇异性。 相似文献
20.
三维非线性有限元与弹性边界元耦合数值方法 总被引:1,自引:0,他引:1
本文系统地讨论了以下三个问题:(1) 有限元与边界元耦合中的几个数值问题,其中包括:边界积分方程的凝聚、等效刚度矩阵的对称化及面力不连续的处理;(2) 弹塑性有限元与弹性边界元的耦合;(3) 弹粘塑性有限元与弹性边界元的耦合及数值计算稳定性条件。 相似文献