scholarly journals MODELLING OF CRACK PROPAGATION: COMPARISON OF DISCRETE LATTICE SYSTEM AND COHESIVE ZONE MODEL

2020 ◽  
Vol 26 ◽  
pp. 39-44 ◽  
Author(s):  
Karel Mikeš ◽  
Franz Bormann ◽  
Ondřej Rokoš ◽  
Ron H.J. Peerlings
Keyword(s):  
Crack Propagation ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Process Zone ◽  
Crack Opening ◽  
Lattice Models ◽  
Bending Test ◽  
Zone Model ◽  
Realistic Problem ◽  
Micro Structures

Lattice models are often used to analyze materials with discrete micro-structures mainly due to their ability to accurately reflect behaviour of individual fibres or struts and capture macroscopic phenomena such as crack initiation, propagation, or branching. Due to the excessive number of discrete interactions, however, such models are often computationally expensive or even intractable for realistic problem dimensions. Simplifications therefore need to be adopted, which allow for efficient yet accurate modelling of engineering applications. For crack propagation modelling, the underlying discrete microstructure is typically replaced with an effective continuum, whereas the crack is inserted as an infinitely thin cohesive zone with a specific traction-separation law. In this work, the accuracy and efficiency of such an effective cohesive zone model is evaluated against the full lattice representation for an example of crack propagation in a three-point bending test. The variational formulation of both models is provided, and obtained results are compared for brittle and ductile behaviour of the underlying lattice in terms of force-displacement curves, crack opening diagrams, and crack length evolutions. The influence of the thickness of the process zone, which is present in the full lattice model but neglected in the effective cohesive zone model, is studied in detail.

scholarly journals An Improved Cohesive Zone Model for Interface Mixed-Mode Fractures of Railway Slab Tracks

2021 ◽  
Vol 11 (1) ◽  
pp. 456
Author(s):  
Yanglong Zhong ◽  
Liang Gao ◽  
Xiaopei Cai ◽  
Bolun An ◽  
Zhihan Zhang ◽  
...  
Keyword(s):  
Interface Crack ◽  
Cohesive Zone ◽  
Mixed Mode ◽  
Cohesive Zone Model ◽  
Complex Loading ◽  
Bending Test ◽  
Mixed Mode Fracture ◽  
Zone Model ◽  
Slab Track ◽  
Interfacial Cracks

The interface crack of a slab track is a fracture of mixed-mode that experiences a complex loading–unloading–reloading process. A reasonable simulation of the interaction between the layers of slab tracks is the key to studying the interface crack. However, the existing models of interface disease of slab track have problems, such as the stress oscillation of the crack tip and self-repairing, which do not simulate the mixed mode of interface cracks accurately. Aiming at these shortcomings, we propose an improved cohesive zone model combined with an unloading/reloading relationship based on the original Park–Paulino–Roesler (PPR) model in this paper. It is shown that the improved model guaranteed the consistency of the cohesive constitutive model and described the mixed-mode fracture better. This conclusion is based on the assessment of work-of-separation and the simulation of the mixed-mode bending test. Through the test of loading, unloading, and reloading, we observed that the improved unloading/reloading relationship effectively eliminated the issue of self-repairing and preserved all essential features. The proposed model provides a tool for the study of interface cracking mechanism of ballastless tracks and theoretical guidance for the monitoring, maintenance, and repair of layer defects, such as interfacial cracks and slab arches.

scholarly journals Numerical Study of the Fatigue Crack in Welded Beam-To-Column Connection Using Cohesive Zone Model

2006 ◽  
Vol 324-325 ◽  
pp. 847-850 ◽  
Author(s):  
Cedric Lequesne ◽  
A. Plumier ◽  
H. Degee ◽  
Anne Marie Habraken
Keyword(s):  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Numerical Study ◽  
Damage Model ◽  
Three Dimensional ◽  
Fatigue Behaviour ◽  
Bending Test ◽  
Zone Model ◽  
Moment Resisting Frame ◽  
Moment Resisting

The fatigue behaviour of the welded beam-to-column connections of steel moment resisting frame in seismic area must be evaluated. The cohesive zone model is an efficient solution to study such connections by finite elements. It respects the energetic conservation and avoids numerical issues. A three-dimensional cohesive zone model element has been implemented in the home made finite element code Lagamine [1]. It is coupled with the fatigue continuum damage model of Lemaître and Chaboche [2]. The cohesive parameters are identified by the inverse method applied on a three points bending test modelling.

scholarly journals FINITE ELEMENT MODELING OF THE CRACK PROPAGATION IN RC BEAMS BY USING ENERGY APPROACH

2015 ◽  
pp. 211-217
Author(s):  
Shahriar Shahbazpanahi ◽  
Chia Paknahad
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Cohesive Zone Model ◽  
Process Zone ◽  
Mesh Size ◽  
Energy Dissipation Rate ◽  
Energy Approach ◽  
Interface Element ◽  
Zone Model ◽  
Steel Bars

In present study, an interface element with nonlinear spring is used to simulate cohesive zone model (CZM) in reinforced concrete (RC) beam for Mode I fracture. The virtual crack closure technique (VCCT) is implemented to model the propagation of the fracture process zone (FPZ). This model can be calculated the energy release rate by using new method from energy approach. Energy dissipation rate by steel bars is obtained to affect on the crack propagation criterion to implement in finite element method. The numerical results are compared with references result available in the literature. It is observed that the FPZ is increased linearly and then stay constant. It may be due to effect of steel bars or inherent behavior of FPZ. The results show that the proposed model does not depend on mesh size.

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