Zongying Fu¹, Yongdong Zhou¹, Tingguo Yan², Yun Lu^1,*

Journal of Renewable Materials, Vol.11, No.1, pp. 93-102, 2023, DOI:10.32604/jrm.2023.021808

Abstract Drying crack is a common phenomenon occurring during moisture discharge from wood, reducing efficient wood utilization. Drying crack is primarily caused by drying stress, and the reasonable methods for determining drying stress are sparse. In this study, the initiation and propagation of cracks during wood discs drying were simulated using the extended finite element method (XFEM). The distribution of drying stress and displacement was analyzed at different crack conditions based on the simulation results. This study aimed to solve the problem of the limitation of drying stress testing methods and provide a new idea for the study of wood drying… More >

Fang Shi^1,*, Daobing Wang², Xiaogang Chen¹

CMES-Computer Modeling in Engineering & Sciences, Vol.127, No.2, pp. 575-598, 2021, DOI:10.32604/cmes.2021.015384

Abstract Field data suggests that carbonate reservoirs contain abundant natural fractures and cavities. The propagation mechanisms of hydraulic fractures in fracture-cavity reservoirs are different from conventional reservoirs on account of the stress concentration surrounding cavities. In this paper, we develop a fully coupled numerical model using the extended finite element method (XFEM) to investigate the behaviors and propagation mechanisms of hydraulic fractures in fracture-cavity reservoirs. Simulation results show that a higher lateral stress coefficient can enhance the influence of the natural cavity, causing a more curved fracture path. However, lower confining stress or smaller in-situ stress difference can reduce this influence,… More >

Pengfei Zhu¹, Qinghui Zhang^2,*

CMES-Computer Modeling in Engineering & Sciences, Vol.124, No.1, pp. 107-127, 2020, DOI:10.32604/cmes.2020.09831

Abstract There are several difficulties in generalized/extended finite element methods (GFEM/XFEM) for moving interface problems. First, the GFEM/XFEM may be unstable in a sense that condition numbers of system matrices could be much bigger than those of standard FEM. Second, they may not be robust in that the condition numbers increase rapidly as interface curves approach edges of meshes. Furthermore, time stepping schemes need carrying out carefully since both enrichment functions and enriched nodes in the GFEM/XFEM vary in time. This paper is devoted to proposing the stable and robust GFEM/XFEM with effi- cient time stepping schemes for the parabolic interface… More >

Zhongmin Xiao¹, Wengang Zhang², Yanmei Zhang^{1, *}, Mu Fan³

CMC-Computers, Materials & Continua, Vol.62, No.1, pp. 267-280, 2020, DOI:10.32604/cmc.2020.06567

Abstract Fluctuated loadings from currents, waves and sea ground motions are observed on offshore steel pipelines, and they will result in small cracks to propagate continuously and cause unexpected damage to offshore/geotechnical infrastructures. In spite of the availability of efficient techniques and high-power computers for solving crack problems, investigations on the fatigue life of offshore pipelines with 3D interacting cracks are still rarely found in open literature. In the current study, systematic numerical investigations are performed on fatigue crack growth behaviours of offshore pipelines containing coplanar and non-coplanar cracks. Extended finite element method (XFEM) is adopted to simulate the fatigue crack… More >

Yana Wang^1,2,3,4, Ruodi Jia^1,5, Fengrui Liu^1,5,6,*

CMES-Computer Modeling in Engineering & Sciences, Vol.120, No.1, pp. 215-234, 2019, DOI:10.32604/cmes.2019.06542

Abstract Delamination and matrix cracking are two common failure mechanisms in composite structures, and are usually coupled with each other, leading to multiple failures pattern. This paper proposed a fast damage prediction methodology for composite laminated structures based on the ply-by-ply 2D (two dimensional) FE model of composite laminates in the transverse plane. The layer-wise 2D FE model was firstly used in conjunction with the integrated XFEM/CE strategy, which simulated the interface delamination with cohesive elements and the intra-ply matrix crack with XFEM (extended finite element method). To realize ply-by-ply 2D FE (finite element) modeling of composite laminates, two 2D material… More >

Xue-cong Liu¹, Qing Zhang^1,2, Xiao-zhou Xia¹

CMES-Computer Modeling in Engineering & Sciences, Vol.113, No.4, pp. 411-427, 2017, DOI:10.3970/cmes.2017.113.411

Abstract The manuscript titled “The Stable Explicit Time Stepping Analysis with a New Enrichment Scheme by XFEM,” has been retracted from the Computer Modeling in Engineering & Sciences (CMES), vol. 113, no. 4. Retraction of this article is made upon the request of the authors, Xue-cong Liu, Qing Zhang, and Xiao-zhou Xia. The authors submitted their manuscript on October 7, 2017, and the authors later made a separate request to withdraw their submission when it was still being reviewed. Due to the glitches of the old submission system and failed communications between the managing editor and the corresponding author, the withdraw… More >

Leiting Dong^1,2, Satya N. Atluri^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.5, pp. 379-413, 2013, DOI:10.3970/cmes.2013.090.379

Abstract The SGBEM-FEM alternating method is compared with the recently popularized XFEM, for analyzing mixed-mode fracture and fatigue growth of 3D nonplanar cracks in complex solid and structural geometries. A large set of 3D examples with different degrees of complexity is analyzed by the SGBEM-FEM alternating method, and the numerical results are compared with those obtained by XFEM available in the open literature. It is clearly shown that: (a) SGBEM-FEM alternating method gives extremely high accuracy for the stress intensity factors; but the XFEM gives rather poor computational results, even for the most simple 3D cracks; (b) while SGBEM-FEM alternating method… More >

Leiting Dong^1,2, Satya N. Atluri^1,3

CMES-Computer Modeling in Engineering & Sciences, Vol.90, No.2, pp. 91-146, 2013, DOI:10.3970/cmes.2013.090.091

Abstract In this paper, and its companion Part 2 [Dong and Atluri (2013b)], the Symmetric Galerkin Boundary Element Method (SGBEM), and the SGBEM-FEM alternating/coupling methods, are compared with the recently popularized Extended Finite Element Method (XFEM), for analyzing fracture and fatigue crack propagation in complex structural geometries. The historical development, and the theoretical/algorithmic formulations, of each method are succinctly reviewed. The advantages and disadvantages of each method are critically discussed. A comprehensive evaluation of the performances of the SGBEM-based methods, and their comparison with XFEM, in modeling cracked solid structures undergoing fatigue crack-growth is carried out. A thorough examination of a… More >

N. Vu-Bac¹, H. Nguyen-Xuan², L. Chen³, S. Bordas⁴, P. Kerfriden⁴, R.N. Simpson⁴, G.R. Liu⁵, T. Rabczuk¹

CMES-Computer Modeling in Engineering & Sciences, Vol.73, No.4, pp. 331-356, 2011, DOI:10.3970/cmes.2011.073.331

Abstract This paper aims to incorporate the node-based smoothed finite element method (NS-FEM) into the extended finite element method (XFEM) to form a novel numerical method (NS-XFEM) for analyzing fracture problems of 2D elasticity. NS-FEM uses the strain smoothing technique over the smoothing domains associated with nodes to compute the system stiffness matrix, which leads to the line integrations using directly the shape function values along the boundaries of the smoothing domains. As a result, we avoid integration of the stress singularity at the crack tip. It is not necessary to divide elements cut by cracks when we replace interior integration… More >

Xue-cong Liu¹, Qing Zhang^1,*, Xiao-zhou Xia¹

CMC-Computers, Materials & Continua, Vol.53, No.3, pp. 187-206, 2017, DOI:10.3970/cmc.2017.053.203

Abstract This paper focuses on the study of the stability of explicit time integration algorithm for dynamic problem by the Extended Finite Element Method (XFEM). A new enrichment scheme of crack tip is proposed within the framework of XFEM. Then the governing equations are derived and evolved into the discretized form. For dynamic problem, the lumped mass and the explicit time algorithm are applied. With different grid densities and different forms of Newmark scheme, the Dynamic Stress Intensity Factor (DSIF) is computed by using interaction integral approach to reflect the dynamic response. The effectiveness of the proposed scheme is demonstrated through… More >