The project involves nonlinear finite element modeling using the commercial finite element code ABAQUS. The project involves using a newly developed user element subroutine to study structural response at small scale.

Purpose

The underlying microstructure of a material is not taken into account in conventional plasticity models as those theories consider the material as homogeneous continuum. On the other hand, modeling the actual microstructure of the material can be a comprehensive and tedious work exposing a great level of unnecessary details. Nevertheless in many cases, it is desirable to include the underlying microstructure on an average way in order to predict the influence of e.g. deformation localization and crack growth on the macroscopic structural behavior or to model mechanical devices on the micro scale. Recently, enhanced plasticity theories have been proposed incorporating such effects though incorporated length scales. The project seeks to investigate the applicability of one of these theories.

Description

A strain gradient plasticity theory developed at Harvard and Cambridge University in 2001 has been implemented in the user subroutine interface used in the commercial finite element code ABAQUS. This implementation can either be used to reveal the applicability of the theory on a class of structural problems or to solve a technical problem where the material length scale can be considered as important. During the project, knowledge on the applicability of commercial finite element code used with brand new continuums theories will be obtained.



The figure show the model predicting the stress state at a crack tip using a conventional plasticity model and the enhanced model implemented in ABAQUS, respectively. The latest shows a much higher stress level predicting an earlier macroscopic failure in the material.

Qualifications

Mechanics of materials and continuum mechanics, finite element modeling. Knowledge on plasticity theories, non-linear finite element modeling and on using ABAQUS an advantage but is not essential.

Project form

Thesis Final year project

Subjects

Materials

Duration