COMSOL Multiphysics^® 6.2 Release Highlights

Nonlinear Structural Materials Module Updates

For users of the Nonlinear Structural Materials Module, COMSOL Multiphysics^® version 6.2 provides new functionality for parameter estimation, new material models for polymer viscoplasticity, and an update to the kinematic hardening model that enables it to handle large plastic strains. Read more about the updates below.

Parameter Estimation

In this version, enhanced parameter estimation capabilities have been introduced, including improvements to the Levenberg–Marquardt and interior point optimizer (IPOPT) solvers. These additions can significantly enhance the performance of parameter estimation of experimental data, including uniaxial, biaxial, and cyclic load cases. Three new tutorial models in the Application Gallery demonstrate this new functionality:

• parameter_estimation_hyperelasticity
• parameter_estimation_plasticity
• parameter_estimation_polymer_viscoplasticity

Polymer Viscoplasticity

In order to accurately analyze structures made of solid polymer materials, new material models for polymer viscoplasticity have been added. These include the Bergstrom–Boyce, Bergstrom–Bischoff, and parallel network models. This new framework can handle large viscoplastic strains, and it is based on the multiplicative decomposition of deformation gradients. You can see these new additions in the following tutorial models:

• chloroprene_rubber_compression_test
• buckling_hdpe_linear
• small_punch_test
• parameter_estimation_polymer_viscoplasticity

Fiber Enhancements

Version 6.2 introduces several improvements to the Fiber feature, including:

• Compressible fibers within the Holzapfel–Gasser–Ogden hyperelastic material model
• The Thermal Expansion feature for fibers embedded in hyperelastic materials
• The Uniaxial data material model for handling nonlinear stress–strain relationships for fibers within the Linear Elastic Material and Nonlinear Elastic Material features

These new improvements can be seen in the new Tire Inflation tutorial model.

Shape Memory Alloy Enhancements

The updates for shape memory alloys include:

• Enhanced flexibility in specifying material parameters for phase transformation, allowing inputs to be entered as start and finish stresses or start and finish temperatures
• Introduction of a new predefined plot showing the stress–temperature phase diagram, which illustrates the austenite-to-martensite transition
• Significantly improved penalty method for enforcing upper bounds on transformation strains
• Inclusion of the Prager–Lode yield surface, enabling the modeling of anisotropic deformation for tension or compression
• Introduction of large-strain plasticity capabilities

You can see these enhancements in the new Uniaxial Loading of Shape Memory Alloy Using Souza–Auricchio Model tutorial model.

Viscoplastic Material Model for Lithium

A new material model, Anand–Narayan, has been added to the Viscoplasticity feature. This material model specifically targets the properties of lithium in battery applications.

New Phase-Field Damage Multiphysics Interface

The new Phase-Field Damage multiphysics interface combines a Solid Mechanics interface with the new Phase-Field in Solids interface through a Phase-Field Damage bidirectional multiphysics coupling. The stress or the strain energy density drives the evolution of the phase field, and the phase field determines the degree of damage to the elastic material model.

New Tutorial Models

COMSOL Multiphysics^® version 6.2 brings several new tutorial models to the Nonlinear Structural Materials Module.