Development of shear locking-free shell elements using an enhanced assumed strain formulation

The degenerated approach for shell elements of Ahmad and co-workers is revisited in this paper. To avoid transverse shear locking effects in four-node bilinear elements, an alternative formulation based on the enhanced assumed strain (EAS) method of Simo and Rifai is proposed directed towards the transverse shear terms of the strain field. In the first part of the work the analysis of the null transverse shear strain subspace for the degenerated element and also for the selective reduced integration (SRI) and assumed natural strain (ANS) formulations is carried out. Locking effects are then justified by the inability of the null transverse shear strain subspace, implicitly defined by a given finite element, to properly reproduce the required displacement patterns. Illustrating the proposed approach, a remarkably simple single-element test is described where ANS formulation fails to converge to the correct results, being characterized by the same performance as the degenerated shell element. The adequate enhancement of the null transverse shear strain subspace is provided by the EAS method, enforcing Kirchhoff hypothesis for low thickness values and leading to a framework for the development of shear-locking-free shell elements. Numerical linear elastic tests show improved results obtained with the proposed formulation. Copyright (C) 2001 John Wiley Sons, Ltd

Quadrilateral elements for the solution of elasto-plastic finite strain problems

In this paper two plane strain quadrilateral elements with two and four variables, are proposed. These elements are applied to the analysis of finite strain elasto-plastic problems. The elements are based on the enhanced strain and B-bar methodologies and possess a stabilizing term. The pressure and dilatation fields are assumed to be constant in each element's domain and the deformation gradient is enriched with additional variables, as in the enhanced strain methodology. The formulation is deduced from a four-field functional, based on the imposition of two constraints: annulment of the enhanced part of the deformation gradient and the relation between the assumed dilatation and the deformation gradient determinant. The discretized form of equilibrium is presented, and the analytical linearization is deduced, to ensure the asymptotically quadratic rate of convergence in the Newton-Raphson method. The proposed formulation for the enhanced terms is carried out in the isoparametric domain and does not need the usually adopted procedure of evaluating the Jacobian matrix in the centre of the element. The elements are very effective for the particular class of problems analysed and do not present any locking or instability tendencies, as illustrated by various representative examples. Copyright (C) 2001 John Wiley & Sons, Ltd

Analysis and diagnosis of a hand tools production system

All rights reserved. Engineers must have a set of professional competences, which includes sound technical knowledge and the ability to solve engineering problems, integrated with a set of transversal competences, which must mobilized for managing projects, working in teams and communicate with the others effectively. The development of these sets of competences can be supported by projects in interaction with companies. This article reports the work developed by a group of students on the Integrated Project of the 4 th year of Industrial Engineering and Management of the University of Minho. The main objective of this work is to describe the type of project that a group of students can develop in interaction with an industrial company, and reflect about the main results that this project have for the development of their competences and for the company. This is a descriptive paper based upon on reports and the experience of the students. The target of the project was the diagnosis and analysis of a production system in an industrial environment. The company chosen to develop this project is a multinational and pioneer company on the manufacturing of hand tools. The content of this article will mainly cover the internal supplier of materials (Mizusumashi), namely the standardization of the Mizusumashi route and the improvement of the components` warehouse (materials organization and visual management). The suggested modifications can result in a 30% decrease of the time wasted in the warehouse, a 20% decrease of the time it takes the Mizusumashi to complete a full route, reaching the 45 minutes the company requested. The students were able to fulfil the project milestones and integrate the company culture in their weekly visits, during the 15 weeks of the project. Furthermore, the company showed to be very satisfied with their behaviour and performance.(undefined)info:eu-repo/semantics/publishedVersio

ABAQUS implementation of phase_field model for brittle fracture

ABAQUS implementation of phase_field model for brittle fractur

Coulomb frictional contact by explicit projection in the cone for _nite displacement quasi-static problems

Coulomb frictional contact by explicit projection in the cone for _nite displacement quasi-static problem

An alternative formulation for quasi-static frictional and cohesive contact problems

An alternative formulation for quasi-static frictional and cohesive contact problem

An extended isogeometric thin shell analysis based on Kirchhoff-Love theory

An extended isogeometric thin shell analysis based on Kirchho_-Love theor

Architecture tradeoffs of integrating a mesh generator to partition of unity enriched object-oriented finite element software

We explore the tradeoffs of using an internal mesher in a XFEM code. We show that it allows an efficient enrichement detection scheme, while retaining the ability to have welladapted meshes. We provide benchmarks highlighting the considerable gains which can be expected from a well designed architecture. The efficiency of the proposed algorithm is shown by solving fracture mechanics problems of densely micro-cracked bodies including adaptive mesh refinement