排序方式: 共有27条查询结果,搜索用时 31 毫秒
1.
E. Giner F. J. Fuenmayor J. E. Tarancn 《International journal for numerical methods in engineering》2004,59(4):533-558
In this paper, an error estimator that quantifies the effect of the finite element discretization error on the computation of the stress intensity factor in linear elastic fracture mechanics is presented. In order to obtain the proposed estimator, a shape design sensitivity analysis (SDSA) is applied to the fracture mechanics problem. Following this approach, one of the most efficient post‐processing techniques for computing the strain energy release rate G, the well‐known EDI method, may be interpreted as a continuum method of the SDSA. The proposed error estimator is based on the recovery of the gradient fields and its reliability has been checked by means of numerical problems, yielding very good estimations of the true error. The new estimator remarkably improves the results given by a previous error estimator, which is based on a discrete analytical approach of SDSA. As a consequence, the combination of the new error estimator and the result given by the EDI method provides a much more accurate estimation of G. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
2.
3.
J.J. Ródenas O.A. González-Estrada P. Díez F.J. Fuenmayor 《Computer Methods in Applied Mechanics and Engineering》2010,199(37-40):2607-2621
This paper introduces a recovery-type error estimator yielding upper bounds of the error in energy norm for linear elastic fracture mechanics problems solved using the extended finite element method (XFEM). The paper can be considered as an extension and enhancement of a previous work in which the upper bounds of the error were developed in a FEM framework. The upper bound property requires the recovered solution to be equilibrated and continuous. The proposed technique consists of using a recovery technique, especially adapted to the XFEM framework that yields equilibrium at a local level (patch by patch). Then a postprocess based on the partition of unity concept is used to obtain continuity. The result is a very accurate but only nearly-statically admissible recovered stress field, with small equilibrium defaults introduced by the postprocess. Sharp upper bounds are obtained using a new methodology accounting for the equilibrium defaults, as demonstrated by the numerical tests. 相似文献
4.
A contour integral method to compute the generalized stress intensity factor in complete contacts under sliding conditions 总被引:1,自引:0,他引:1
In complete contact fretting problems under global sliding conditions, the stress state at the corner of the contact zone is usually singular (assuming elastic behaviour). This stress state is characterized by two parameters: the order of singularity and the generalized stress intensity factor (GSIF). The former can be analytically calculated for a given problem. However, the GSIF is usually obtained by means of numerical procedures. One of the most used is the application of the stress extrapolation technique in combination with a FE analysis. In this work, a path-independent contour integral is defined which enables the GSIF calculation. Using this novel technique, a much more accurate estimation of the GSIF is obtained for a given discretization. In addition, a refined mesh around the singular point is not needed, because the contour integral can be applied along paths far from the singularity dominated zone due to its path independence. 相似文献
5.
6.
7.
An Abaqus implementation of the extended finite element method 总被引:1,自引:0,他引:1
In this paper, we introduce an implementation of the extended finite element method for fracture problems within the finite element software ABAQUSTM. User subroutine (UEL) in Abaqus is used to enable the incorporation of extended finite element capabilities. We provide details on the data input format together with the proposed user element subroutine, which constitutes the core of the finite element analysis; however, pre-processing tools that are necessary for an X-FEM implementation, but not directly related to Abaqus, are not provided. In addition to problems in linear elastic fracture mechanics, non-linear frictional contact analyses are also realized. Several numerical examples in fracture mechanics are presented to demonstrate the benefits of the proposed implementation. 相似文献
8.
A mortar-based frictional contact formulation for large deformations using Lagrange multipliers 总被引:1,自引:0,他引:1
M. Tur F.J. Fuenmayor P. Wriggers 《Computer Methods in Applied Mechanics and Engineering》2009,198(37-40):2860-2873
In this work a Lagrange multiplier method is proposed to solve 2D Coulomb frictional contact problems in the context of large deformations. As the proposed formulation is based on the mortar method, the constraints are imposed in a weak integral sense along the contact surface. In order to compute the contact integrals, we use a numerical integration based on the definition of the kinematical variables (gap, slip and their variations) at the quadrature points. The linearization of non-linear equations (virtual work and contact constraints) is developed in order to apply a Newton’s method. The examples show that the numerical integration still preserves the optimal rate of convergence of the finite element solution. 相似文献
9.
J. J. Rdenas F. J. Fuenmayor J.E. Tarancn 《International journal for numerical methods in engineering》2004,59(13):1725-1747
The velocity field in shape sensitivity analysis is not uniquely defined although it must meet numerous theoretical and practical criteria. These practical criteria can be used to compare the existing velocity field computation methods which meet the theoretical criteria, but only in qualitative terms. When the FEM is used in design sensitivity analysis (DSA), due to the FE discretization error, the DSA errors will depend on the design velocity field considered. This paper presents a numerical methodology for quality evaluation of design velocity field computation methods in quantitative terms based on the analysis of the DSA discretization error. The sensitivity of the squared energy norm (χm = ?∥u∥2/?am, am being a design variable) has been taken as the magnitude to measure the error of the DSA. For h‐refinements, the squared error in energy norm (∥ e ( u ) ∥2) and the error in χm(e(χm)) are theoretically related by a constant which is independent of the refinement degree of the FE model. The quality of the design velocity field computation methods can therefore be assessed in terms of the stability of e(χm) /∥e(u) ∥2 in sequences of meshes. An example of the use of this methodology, where six design velocity field computation methods are compared, is presented. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
10.
A fretting fatigue test for a complete contact problem is modeled using the finite element method. The objective is to obtain the response of the specimen-indenter contact under loading–unloading cycles. These are generated by applying a cyclic shear load to the indenter, whose maximum value does not cause global sliding of the indenter, but only partial slip. The evolution of the contact conditions over several cycles is studied, as well as the intensity of the singularities present at the left and right corners, measured through the generalized stress intensity factors. In addition, some conclusions regarding the conditions that lead to partial slip are inferred. This represents a stage in the development of an asymptote-based fretting fatigue model. 相似文献