Cohesive Elements for Shells

A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design

Effective Simulation of Delamination in Aeronautical Structures Using Shells and Cohesive Elements

A cohesive element for shell analysis is presented. The element can be used to simulate the initiation and growth of delaminations between stacked, non-coincident layers of shell elements. The procedure to construct the element accounts for the thickness offset by applying the kinematic relations of shell deformation to transform the stiffness and internal force of a zero-thickness cohesive element such that interfacial continuity between the layers is enforced. The procedure is demonstrated by simulating the response and failure of the Mixed Mode Bending test and a skin-stiffener debond specimen. In addition, it is shown that stacks of shell elements can be used to create effective models to predict the inplane and delamination failure modes of thick components. The results indicate that simple shell models can retain many of the necessary predictive attributes of much more complex 3D models while providing the computational efficiency that is necessary for design

A simulation method for fatigue-driven delamination in layered structures involving non-negligible fracture process zones and arbitrarily shaped crack fronts

Most of the existing methods for fatigue-driven delamination are limited to two-dimensional (2D) applications or their predictive capabilities have not been validated in three-dimensional (3D) problems. This work presents a new cohesive zone-based computational method for simulating fatigue-driven delamination in the analysis of 3D structures without crack migration. The method accurately predicts fatigue propagation of non-nelgigible fracture process zones with arbitrarily shaped delamination fronts. The model does not require any kind of fitting parameter since all the input parameters are obtained experimentally from coupon tests. The evaluation of the energy release rate is done using two new techniques recently developed by the authors (the growth driving direction and the mode-decomposed J-integral) leading to an accurate prediction of delamination propagation under mixed-mode and non-self-similar growing conditions. The new method has been implemented as a UEL for Abaqus and validated against an experimental benchmark case with varying crack growth rate and shape and extension of the fracture process zone.Comment: 37 pages, 14 figures, 7 table

The global carbon budget and the Paris agreement

Purpose–The main purpose of this paper is to introduce the concept of global carbon budget (GCB) as akey concept that should be introduced as a reference when countries formulate their mitigation contributionsin the context of the Paris Agreement and in all the monitoring, reporting and verification processes that mustbe implemented according to the decisions of the Paris Summit.Design/methodology/approach–A method based on carbon budget accounting is used to analyze theintended nationally determined contributions (INDCs) submitted by the 15 countries that currently head theranking of global emissions. Moreover, these INDCs are analyzed and compared with each other. Sometimes,inadequate methodologies and a diverse level of ambition in the formulated targets are observed.Findings–It is found that the INDCs of those 15 countries alone imply the release into the atmosphere of 84per cent of the GCB for the period 2011-2030, and 40 per cent of the GCB available until the end of the century.Originality/value–This is thefirst time the INDCs of the top 15 emitters are analyzed. It is also thefirstanalysis made using the GCB approach. This paper suggests methodological changes in the way that thefuture NDCs might be formulated.Peer ReviewedPostprint (published version

Simulation of Delamination Propagation in Composites Under High-Cycle Fatigue by Means of Cohesive-Zone Models

A damage model for the simulation of delamination propagation under high-cycle fatigue loading is proposed. The basis for the formulation is a cohesive law that links fracture and damage mechanics to establish the evolution of the damage variable in terms of the crack growth rate dA/dN. The damage state is obtained as a function of the loading conditions as well as the experimentally-determined coefficients of the Paris Law crack propagation rates for the material. It is shown that by using the constitutive fatigue damage model in a structural analysis, experimental results can be reproduced without the need of additional model-specific curve-fitting parameters

Simulation of Delamination Under High Cycle Fatigue in Composite Materials Using Cohesive Models

A new thermodynamically consistent damage model is proposed for the simulation of high-cycle fatigue crack growth. The basis for the formulation is an interfacial degradation law that links Fracture Mechanics and Damage Mechanics to relate the evolution of the damage variable, d, with the crack growth rate da/dN. The damage state is a function of the loading conditions (R and (Delta)G) as well as the experimentally-determined crack growth rates for the material. The formulation ensures that the experimental results can be reproduced by the analysis without the need of additional adjustment parameters

Equity in the Paris Agreement regime are current NDCs built on equity?

Pòster presentat a la 27ª Conferència de la Convenció Marc per al Canvi Climàtic de Nacions Unides (COP27), dins del procés del Diàleg Tècnic del Global StocktakeObjectius de Desenvolupament Sostenible::16 - Pau, Justícia i Institucions SòlidesObjectius de Desenvolupament Sostenible::13 - Acció per al ClimaPreprin