Constitutive Modelling of Solid Materials

Group Overview

The constitutive model or material model, which renders the local stress in response to the local strain or strain history, is fundamental to any application of solid mechanics. In the context of computational structural finite element analysis, which is today indispensable tool in the engineering industry, the constitutive model is represented in terms of the local stress update algorithm.

While suitable models for a range of different material behaviours have been available for some time, the recent progress in Materials Engineering and the trend towards innovative, more efficient, more accurate and more complex industrial and scientific applications require continuous research and development efforts in the area of constitutive modelling.

Constitutive modelling in the finite strain regime

The group has made significant contributions to the formulation of thermodynamically consistent rate-dependent and rate independent elastic and inelastic material models and their algorithmic implementation.

Crystal plasticity

The team has developed various crystal plasticity models to elucidate the underlying processes of deformation in individual crystals, such as dislocation slip and twinning. These models have found extensive application in simulating the mechanical properties of polycrystalline materials, including alloys and metals.

Geomechanics

Working with our industry partners, the team developed new constitutive models for soil and soft rock, to consider coupled effects of pressure, heat, and chemicals. A main drive in these investigations was the comparison of explicit and implicit treatments, and the response when considering like-to-like geotechnical problems. Comprehensive assessments were carried out over a range of different stress states, including the main areas of hydrostatic compression, shear dilatancy and shear compaction.

Machine learning for constitutive modelling

A generic neural network based stress update procedure was developed that can be trained on stress-strain data sequences obtained from physical or numerical experiments. The strategy is suitable for elastic or inelastic material and provides a mechanism for the evolution of hidden internal states. In the uniaxial case, certain standard material models can be recovered exactly. The strategy has been integrated and tested in finite element code.

Specialisation: finite element methods, solid mechanics, constitutive modelling, multi-scale analysis

Specialisation: finite element methods, solid mechanics, constitutive modelling, coupled problems

Specialisation: finite element methods, coupled problems, fluid and solid mechanics, constitutive modelling

Specialisation: crystal plasticity, geomechanics, peridynamics, phase-field models