A reduced-input cohesive zone model with regularized extended finite element method for fatigue analysis of laminated composites in Abaqus

2021 ◽  
pp. 114494
Author(s):  
Yu-Jui Liang ◽  
Carlos G. Dávila ◽  
Endel V. Iarve
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cohesive Zone ◽  
Extended Finite Element Method ◽  
Cohesive Zone Model ◽  
Laminated Composites ◽  
Fatigue Analysis ◽  
Zone Model ◽  
Extended Finite Element ◽  
Element Method

Use of the Extended Finite Element Method in the Assessment of Delayed Hydride Cracking

2016 ◽  
Author(s):  
Martin Booth ◽  
Michael Martin
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Cohesive Zone ◽  
Zirconium Alloy ◽  
Extended Finite Element Method ◽  
Process Zone ◽  
Zirconium Hydride ◽  
Extended Finite Element ◽  
Delayed Hydride Cracking ◽  
Element Method

Zirconium alloys, as used in water-cooled nuclear reactors, are susceptible to a time-dependent failure mechanism known as Delayed Hydride Cracking, or DHC. Corrosion of zirconium alloy in the presence of water generates hydrogen that subsequently diffuses through the metallic structure in response to concentration, temperature and hydrostatic stress gradients. As such, regions of increased hydrogen concentration develop at stress concentrating features, leading to zirconium hydride precipitation. Regions containing zirconium hydride are brittle and prone to failure if plant transient loads are sufficient. This paper demonstrates the application of the Extended Finite Element Method, or XFEM, to the assessment of the DHC susceptibility of stress concentrating features, typical of those considered in the structural integrity assessment of heavy water pressure tube reactors. The method enables the calculation of a DHC threshold load. This paper builds on the process-zone approach that is currently used to provide the industry-standard DHC assessment of zirconium alloy pressure tubes and also recent developments that have extended the application of the process-zone approach to arbitrary geometries by the use of finite element cohesive-zone analysis. In the standard cohesive-zone approach, regions of cohesive elements are situated in discrete locations where the formation of zirconium hydride is anticipated. In contrast, the use of XFEM based cohesive formulations removes the requirement to define cohesive zones a priori, thereby allowing the assessment of geometries in which the location of hydride material is not known.

Analysis of the initiation and propagation of fatigue cracks in the CRTS II slab track inter-layer using FE-SAFE and XFEM

2018 ◽  
Vol 233 (7) ◽  
pp. 678-690 ◽  
Author(s):  
Hong Xiao ◽  
Yan-rong Zhang ◽  
Qi-hang Li ◽  
Feng Jin ◽  
Mahantesh M Nadakatti
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Extended Finite Element Method ◽  
Fatigue Cracks ◽  
Element Model ◽  
Fatigue Analysis ◽  
Railway Track ◽  
Extended Finite Element ◽  
Element Analysis ◽  
Element Method

In this study, a novel method for analysing inter-layer defects in slab tracks was proposed, based on fatigue analysis and the extended finite element method. The inter-layer gap of China Railway Track System (CRTS) II slab tracks was analysed. First, a finite element model was established to analyse the stresses in mortar layer under train and temperature loading. Secondly, the results of the stress analysis of the mortar layer were assessed using a fatigue analysis software for calculating the fatigue life of the mortar layer and the areas that fail first. Finally, in an extended finite element analysis, an initial gap was applied over the area that fails first, as determined through the fatigue analysis of the mortar layer. The patterns of the gaps at the ends, in the central part of the edge, and at the corner of the inter-mortar layer were observed and compared. Results show that the new method, which combines fatigue analysis and the extended finite element method, can address the discontinuity problem of the inter-layer slab defects in ballastless tracks, enabling the development process to be simulated. The rate at which the area of gapping increases can be used to characterize the development of the inter-layer gap in slab tracks.

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