Analysis of large elasto-plastic deformations with new compatible mode elements

• Type: Article in International Conference Proceedings Book
• Date: 2000

Authors

José César de Sá (Author) FEUP; Pedro Miguel Areias (Author) Other; Renato Natal Jorge (Author) FEUP

Conference proceedings International

Title: European Congress on Computational Methods in Applied Sciences and Engineering, ECCOMAS 2000

Pages: 499-499

Indexing

Scopus - 2 Citations

Other information

Authenticus ID: P-009-4YJ

Resumo (PT): Neste artigo propõe-se uma extensão do trabalho apresentado anteriormente para pequenas deformações com uma interpolação compatível para os termos do gradiente de deformação acrescentados. O novo conceito aqui apresentado consiste na combinação das técnicas B-bar e das deformações acrescentadas mediante a inclusão de um termo de estabilização. O objectivo é a obtenção de uma formulação robusta, sem hourglass, e aplicavél a problemas envolvendo deformações finitas em regime elasto-plástico.

Abstract (EN): In this paper two plane strain quadrilateral elements are proposed, appropriate to the analysis of finite deformation elasto-plastic problems. These elements are based on the B-bar and the Enhanced Assumed Strain (EAS) techniques and contain a stabilizing term. The pressure and dilatation fields are assumed constant in the elements domain, and the distortional part of the deformation gradient is enhanced with the extra variables. A modified calculation of the dilatation field is adopted, based on the exact value for the standard B-bar element. The two elements presented, denoted as Qi5B-bar and Qi6B-bar have two and four internal variables, respectively. The proposed formulation is an extension of the well known three-field Hu-Washizu functional usually adopted in the u - p formulation. An additional term is introduced to that functional, to impose, by a penalty parameter, the nullity of the deformation gradient enhanced part. The proposed formulation satisfies the Patch-Test without the need for the evaluation of the enhanced derivatives in the element's centre. The equilibrium formulation and linearization details are discussed. It is noticeable that the internal force vector is a straightforward extension of the standard B-bar case. The tangent stiffness is only moderately more complex than the standard B-bar stiffness. A J2 material model is employed, and some examples are presented to illustrate the good behaviour and effectiveness of the two elements. In particular, the Qi5B-bar element has no need of stabilizing term and is computational inexpensive. The new elements did not show any instabilities or locking tendencies.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 19