scholarly journals Simulation of Quasi-Static Crack Propagation by Adaptive Finite Element Method

Metals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 98
Author(s):  
Abdulnaser M. Alshoaibi ◽  
Yahya Ali Fageehi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Fatigue Life ◽  
Stress Intensity ◽  
Crack Growth ◽  
Crack Tip ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Element Method

The finite element method (FEM) is a widely used technique in research, including but not restricted to the growth of cracks in engineering applications. However, failure to use fine meshes poses problems in modeling the singular stress field around the crack tip in the singular element region. This work aims at using the original source code program by Visual FORTRAN language to predict the crack propagation and fatigue lifetime using the adaptive dens mesh finite element method. This developed program involves the adaptive mesh generator according to the advancing front method as well as both the pre-processing and post-processing for the crack growth simulation under linear elastic fracture mechanics theory. The stress state at a crack tip is characterized by the stress intensity factor associated with the rate of crack growth. The quarter-point singular elements are constructed around the crack tip to accurately represent the singularity of this region. Under linear elastic fracture mechanics (LEFM) with an assumption in various configurations, the Paris law model was employed to evaluate mixed-mode fatigue life for two specimens under constant amplitude loading. The framework includes a progressive analysis of the stress intensity factors (SIFs), the direction of crack growth, and the estimation of fatigue life. The results of the analysis are consistent with other experimental and numerical studies in the literature for the prediction of the fatigue crack growth trajectories as well as the calculation of stress intensity factors.

Update: Application of the Finite Element Method to Linear Elastic Fracture Mechanics

2010 ◽  
Vol 63 (2) ◽  
Author(s):  
Leslie Banks-Sills
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Linear Elastic Fracture Mechanics ◽  
The Finite Element Method ◽  
Intensity Factors ◽  
Linear Elastic ◽  
Elastic Fracture ◽  
Element Method

Since the previous paper was written (Banks-Sills, 1991, “Application of the Finite Element Method to Linear Elastic Fracture Mechanics,” Appl. Mech. Rev., 44, pp. 447–461), much progress has been made in applying the finite element method to linear elastic fracture mechanics. In this paper, the problem of calculating stress intensity factors in two- and three-dimensional mixed mode problems will be considered for isotropic and anisotropic materials. The square-root singular stresses in the neighborhood of the crack tip will be modeled by quarter-point, square and collapsed, triangular elements for two-dimensional problems, respectively, and by brick and collapsed, prismatic elements in three dimensions. The stress intensity factors are obtained by means of the interaction energy or M-integral. Displacement extrapolation is employed as a check on the results. In addition, the problem of interface cracks between homogeneous, isotropic, and anisotropic materials is presented. The purpose of this paper is to present an accurate and efficient method for calculating stress intensity factors for mixed mode deformation. The equations presented here should aid workers in this field to carry out similar analyses, as well as to check their calculations with respect to the examples described.

A Coupled SBFEM-FEM Approach for Evaluating Stress Intensity Factors

2013 ◽  
Vol 353-356 ◽  
pp. 3369-3377 ◽  
Author(s):  
Ming Guang Shi ◽  
Chong Ming Song ◽  
Hong Zhong ◽  
Yan Jie Xu ◽  
Chu Han Zhang
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Complex Geometry ◽  
Stress Singularity ◽  
Intensity Factors ◽  
Finite Element Software ◽  
Scaled Boundary Finite Element ◽  
Element Method

A coupled method between the Scaled Boundary Finite Element Method (SBFEM) and Finite Element Method (FEM) for evaluating the Stress Intensity Factors (SIFs) is presented and achieved on the platform of the commercial finite element software ABAQUS by using Python as the programming language. Automatic transformation of the finite elements around a singular point to a scaled boundary finite element subdomain is realized. This method combines the high accuracy of the SBFEM in computing the SIFs with the ability to handle material nonlinearity as well as powerful mesh generation and post processing ability of commercial FEM software. The validity and accuracy of the method is verified by analysis of several benchmark problems. The coupled algorithm shows a good converging performance, and with minimum additional treatment can be able to handle more problems that cannot be solved by either SBFEM or FEM itself. For fracture problems, it proposes an efficient way to represent stress singularity for problems with complex geometry, loading condition or certain nonlinearity.

On XFEM Applications to Crack Surface under External Force

2012 ◽  
Vol 152-154 ◽  
pp. 210-215
Author(s):  
Tian Tang Yu ◽  
Lu Yang Shi
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Extended Finite Element Method ◽  
Crack Surface ◽  
Water Pressure ◽  
Intensity Factors ◽  
Extended Finite Element ◽  
Modeling Growth ◽  
Element Method

The extended finite element method is applied to modeling growth of arbitrary crack with crack surface tractions. Firstly, the extended finite element method is investigated for the stress intensity factor solution of surface traction problems. Secondly, for different water pressure acting on the crack surfaces and different crack length, the variation of the stress intensity factors is investigated. Finally, the process of hydraulic fracturing is simulated with the method. Numerical simulations illustrate that the method can effectively model the fracture problems with surface tractions.

Sensitivity of Stress Intensity Factors with Respect to the Crack Geometry by the Scaled Boundary Finite Element Method

2014 ◽  
Vol 553 ◽  
pp. 737-742
Author(s):  
Morsaleen Shehzad Chowdhury ◽  
Chong Ming Song ◽  
Wei Gao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Shape Sensitivity ◽  
Intensity Factors ◽  
Element Discretization ◽  
Crack Geometry ◽  
Scaled Boundary Finite Element ◽  
Element Method

The sensitivity of the stress intensity factors (SIFs) with respect to the crack geometry, shape sensitivity, plays an important role in the reliability analysis of cracked structures and many other fracture mechanics applications. This paper presents a numerical technique to evaluate the shape sensitivity using the scaled boundary finite element method. It combines the finite element formulations with the boundary element discretization. The crack surface remains meshless. The variation in crack geometry is modelled by applying direct differentiation with respect to the crack geometry, without remeshing. The sensitivity of the stress modes are not required for the calculation of the sensitivity of the SIFs. A numerical example demonstrates the efficiency, accuracy and simplicity of the technique.

Sign in / Sign up

Export Citation Format

Share Document