Extended finite element method in computational fracture. In this paper, the high concrete dam of longtan was used as an example, using the abaqus program based on the extended finite element method to analyze the longtan dam under static and dynamic conditions which has been commonly used for the study of crack growth. The following example shows a named xfembased crack surface. The ddm approach to modeling crackinduced displacement discontinuities employs the meshindependent crack mic technique for crack growth without remeshing, such as the extended finite element method xfem which has been developed over the past decade. The stress intensity factor sif is an important parameter for estimating the life of the cracked structure. Modeling discontinuities as an enriched feature using the extended. We provide details on the data input format together with. The method is based on the rateindependent variational principle of diffuse fracture. Mechanical engineering xfem or extended finite element method is a very wellknown technique and is getting more popular due to its vast application domain. An abaqus implementation of the extended finite element. Analysis of threedimensional fracture mechanics problems. Abaqus implementation of extended finite element method using a. Implementation of extended finite element method using implicit boundary approach by vishal hundraj hotwani december 2011 chair.
A 3d discrete damage modeling methodology for abaqus for. To date, this methodology has been implemented in bsam, an inhouse program, and extensively applied to static and fatigue analysis of. An abaqus implementation of the extended finite element method, efm, doi. Crack modelling with the extended finite element method. Thus, the mathematical discontinuity introduced by means of xfem enables the. Sukumar3, and ted belytschko4 1global engineering and. Buckling is characterized by a sudden sideways failure of a structural member subjected to high compressive stress, where the compressive stress at the point. For an ordinary crack implementation problem, the approximation function for the. Source codes and simulation data for the finite element. Simulation of cracking in high concrete gravity dam using. The proposed technique allows arbitrary insertion of initial cracks. The method of extended elements permits a representation of cracks by nite elements, which does not require to change the mesh to monitor crack propagation 5, causing a revolution when compared with the classical methods.
Citeseerx abaqus implementation of extended finite. The 6061t651 aluminium alloy is one of the most common aluminium alloys for marine components and general structures. Stationary 3d crack analysis with abaqus xfem for integrity assessment of subsea equipment masters thesis in applied mechanics. We provide details on the data input format together with the proposed user element subroutine, which constitutes the core of the finite. An abaqus implementation of the xfem for hydraulic. Rxfem is a variant of the extended finite element method xfem where a continuous approximation of heaviside step function is introduced unlike xfem. Abaqus implementation of extended finite element method using a level set representation for threedimensional fatigue crack growth and life predictions. In this paper, we introduce an implementation of the extended finite element method for fracture problems within the finite element software abaqustm. Its numerical implementation is mostly achieved with standalone codes. This work describes the implementation of the extended finite element method xfem in the abaqus software package. We provide a historical perspective on the development. The proposed implementation to represent the enriched displacement field is based on the superposition of native abaqus elements with umat and uel which is used to connect the superimposed. The purpose of this thesis is to understand the potential of crack modeling using the xfem in abaqus and to. Abaqus implementation of extended finite element method.
The proposed element includes the desired aspects of the xfem so as to model crack propagation without explicit remeshing. A modified 3d xfem element formulation to avoid mesh locking. The phasefield is a scalar variable between 0 and 1 which connects broken and unbroken regions. Citeseerx document details isaac councill, lee giles, pradeep teregowda. The implementation of the extended finite element method in commercial fea softwares is still. Xfem, extended finite element method, creating a new paradigm in the study of cracks 3, 4. The implementation of regularized extended finite element method rxfem in abaqus. The recently developed extended finite element method xfem has been proved as an efficient way to simulate the meshindependent crack propagation problem.
The extended finite element method xfem, also known as generalized finite element method gfem or partition of unity method pum is a numerical technique that extends the classical finite element method fem approach by extending the solution space for solutions to differential equations with discontinuous functions. It is an extension of the conventional finite element method based on the concept of partition of unity by melenk and babuska 1996, which allows local enrichment functions to be easily incorporated into a finite element approximation. The computational model implemented in the provided source codes and simulation data are used to simulate brittle fracture in elastic solids which can be easily extended to simulate ductile or dynamic fracture. An extended finite element method xfem tecnico lisboa. The arbitrary crack is treated by the xfem method without remeshing but using an enrichment of the classical displacementbased. Xfem extended finite element method is one of the many capabilities offered by abaqus for detailed modelling of failure in structural components.
From a family of sfem models, the cellbased finite element method csfem is chosen to be implemented in abaqus, because a smoothing cell in the csfem involves only one element, and hence the implementation can be achieved via the use of the userdefined element library uel. To alleviate the computational burden associated with the insertion of arbitrary cracks into an finite element model, the extended finite element method xfem 2. An elementbased penalty approach is also developed to model crack closure and friction. Using the continuum decohesive finite element for crack growth analysis in fiber reinforced composites. It extends the classical finite element method fem approach by enriching the solution space for solutions to differential equations with discontinuous functions. Our main attention is placed on the modeling of cracks strong discontinuities for quasistatic crack growth simulations in isotropic linear elastic continua. An abaqus implementation of regularized extended finite element method rxfem for modeling the interaction between matrix cracking and delamination in composites. Abstract in this paper, we introduce an implementation of the extended finite element method for fracture problems within the finite element software abaqus tm. Firstly introduced in 1999 by the work of black and belytschko, xfem is a local partition of unity pum enriched finite element method. Implicit crack representation and initialization of the.
Extended finite element method xfem analysis of fiber. In order to model brittle fracture, we have implemented a two and three dimensional phasefield method in the commercial finite element code abaqusstandard. An abaqus implementation of the cellbased smoothed finite. Xfem implementation, and chapter 5 presents numerical results from. The extended finite element method is a partition of unity based method, particularly suitable for modelling crack propagation phenomena, without knowing a priori the crack path. User subroutine uel in abaqus is used to enable the incorporation of extended finite element capabilities.
The extended finite element method xfem is a exible numerical approach developed for general interface problems. The aim of this writting is to give a brief introduction to the extended finite element method xfem and investigation of its practical applications. Assessment of the applicability of xfem in abaqus for. Abaqus implementation of extended finite element method using a level set representation for threedimensional fatigue crack growth and life predictions 1. Singularity enrichment for complete sliding contact using the partition of unity finite element method 2008 ijnme, 76, 14021418. An abaqus implementation of regularized extended finite element method rxfem for modeling the interaction between matrix cracking and delamination in. The extended finite element method xfem, is a numerical technique based on the generalized finite element method gfem and the partition of unity method pum. Modeling discontinuities as an enriched feature using the. Shi j, chopp d, lua j, sukumar n, belytschko t 2010 abaqus implementation of extended finite element method using a level set representation for threedimensional fatigue crack growth and life predictions. We provide details on the data input format together with the proposed user element subroutine, which constitutes the core of. In the xfem formulation, additional degrees of freedom are added to the element along. Abaqus usdfld subroutine for the implementation of a continuous variation of the material elastic properties between integration points.
In this paper, we introduce an implementation of the extended finite element method for fracture problems within the finite element software abaqus tm. The extended finite element method was first introduced by belytschko and black 1999. Given the level set representation of arbitrary crack geometry, the narrow band fmm provides an efficient way to update the. In this paper, the stress intensity factors of a slantcracked plate, which is made of 6061t651 aluminum, have been calculated using extended finite element method. On the implementation of the extended finite element. Geometry of modelled domain and notation the displacement discontinuity w across. Methods of fatiguefracture analysis fatigue crack growth analysis, abaqus, nastran, etc. In recent years, the extended finite element method xfem 1 has emerged as a powerful numerical procedure for the analysis of crack problems.
Thus, the mathematical discontinuity introduced by means of xfem enables the crack growth simulation without the necessity of remeshing. The extended finite element method xfem imechanica. This method was later used by song 3 as a means to more conveniently introduce xfem into the traditional fem framework. A numerical prediction of crack propagation in concrete gravity dams is presented. An abaqus implementation of regularized extended finite. Abaqus implementation of extended finite element method using a level set representation for threedimensional fatigue crack growth and life predictions jianxu shi1, david chopp2, jim lua1, n.
Abstract in this paper, we introduce an implementation of the extended finite element method for fracture problems within the finite element software abaqustm. The xfem extended finite element method, is a new method for. Extended finite element method simulia abaqus software. In addition, the fluid pressure degrees of freedom have been defined on the element to describe the fluid flow. A numerical implementation of the extended finite element method xfem to analyze crack propagation in a structure under dynamic loading is presented in this paper. An abaqus implementation of the extended finite element method. Introduction to extended finite element xfem method. A new finite element has been implemented in abaqus to incorporate the extended finite element method xfem for the solution of hydraulic fracture problems. The implementation of regularized extended finite element. On the finite element implementation of functionally graded materials. Chapter 4 covers some issues relating to abaqus specific. The present implementation is based on the nonlinear finite element method for a. Using extended finite element method for computation of. In the rst case, the methods use a tted mesh approach such that.
A threedimensional extended finite element method xfem coupled with a narrow band fast marching method fmm is developed and implemented in the abaqus finite element package for curvilinear fatigue crack growth and life prediction analysis of metallic structures. It has been widely acknowledged that the method eases crack growth modelling under the assumptions of linear elastic fracture mechanics lefm. Abaqus linear buckling analysis finite element method. An abaqus implementation of the extended finite element method xfem 21 is employed to model crack propagation. Finite element analysis of slant edge crack by abaqus. Iarve 2003 proposed a regularized xfem rxfem for mesh independent matrix cracking mic modeling, which did. A userde ned element was developed containing the analytical functions relating to homogeneous and interface fracture mechanics. Implementation of the regularized extended finite element. This approach is used in abaqusstandard to simulate crack initiation and propagation. Numerical implementation of the extended finite element.
In this paper, we provide a retrospective examination of the developments and applications of the extended finite element method xfem in computational fracture mechanics. Rxfem is a variant of the extended finite element method xfem, where a continuous approximation is used in place of the heaviside step function. The extended finite element method xfem the aim of this writting is to give a brief introduction to the extended finite element method xfem and investigation of its practical applications. The regularized extended finite element method rxfem is a fracture mechanics based technique for progressive failure simulation when multiple damage events such as matrix cracks and delamination are introduced into the finite element model via mesh independent displacement discontinuities. Cast3m implementation of the extended finite element method for cohesive crack 57 g d n f fig.