Stress Singularity in Composite Laminates by Finite Element Method

1986 ◽  
Vol 20 (4) ◽  
pp. 347-364 ◽  
Author(s):  
J.R. Yeh ◽  
I.G. Tadjbakhsh
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Composite Laminates ◽  
Stress Singularity ◽  
Element Method

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.

Mesh Sensitivity and FEA for Multi-Layered Electronic Packaging

1999 ◽  
Vol 123 (3) ◽  
pp. 218-224 ◽  
Author(s):  
Cemal Basaran ◽  
Ying Zhao
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Damage Mechanics ◽  
Stress Singularity ◽  
Free Edge ◽  
Elastic Analysis ◽  
Linear Elastic ◽  
Inelastic Analysis ◽  
Mesh Sensitivity ◽  
Element Method

Multi-layered stacks are commonly used in microelectronic packaging. Traditionally, these systems are designed using linear-elastic analysis either with analytical solutions or finite element method. Linear-elastic analysis for layered structures yields very conservative results due to stress singularity at the free edge. In this paper, it is shown that a damage mechanics based nonlinear analysis not just leads to a more realistic analysis but also provides more accurate stress distribution. In this paper these two approaches are compared. Moreover, mesh sensitivity of the finite element analysis in stack problems is studied. It is shown that the closed form and elastic finite element analyses can only be used for preliminary studies and elastic finite element method is highly mesh sensitive for this problem. In elastic analysis the stress singularity at the free edge makes mesh selection very difficult. Even when asymptotic analysis is used at the free edge, the results are very conservative compared to an inelastic analysis. Rate sensitive inelastic analysis does not suffer from the stress singularity and mesh sensitivity problems encountered in elastic analysis.

Analysis of delamination of composite laminates via extended finite element method based on the layerwise displacement theory and cohesive zone method

2021 ◽  
pp. 146442072110461
Author(s):  
Matheus VM Santos ◽  
Murilo Sartorato ◽  
Anish Roy ◽  
Volnei Tita ◽  
Marcelo L Ribeiro
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Composite Laminates ◽  
Extended Finite Element Method ◽  
Degree Of Freedom ◽  
Bottom Surface ◽  
Extended Finite Element ◽  
Zone Method ◽  
Displacement Theory ◽  
Element Method

Composite laminates are being more employed as fundamental structures due to its low weight and high stiffness. To predict the material response in presence of damage can be demanding due to composite’s complex nature. Hence, superior computational models should be further investigated to speculate a more accurate composite behavior. This paper proposes an extended finite element procedure, based on the layerwise displacement theory, to simulate delamination to composite laminate. It is assumed a cohesive behavior to the damaged domain, described by a traction separation law. An extra degree of freedom associated to the strong discontinuity (delamination) is added at each layer top and bottom surface for out-of-plane displacement. This extra degree of freedom is only active on the failed nodes. To validate the model, a pre-delaminated composite analysis is performed and compared to results already reported in the literature. In addition, all stress components can be precisely calculated due to layer wise displacement field assumption, without any concern about the membrane and shear locking, not to mention its greater computational efficiency when compared to equivalent three-dimensional elements. Therefore, in the present work, it is shown the limitations and potentialities when a cohezive formulation is combined to extended finite element method using a new kind of approach. Additionally, this formulation makes easier to model delaminations using finite element method keeping a good accuracy without the need of cumbersome finite element models.

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