COMSOL Multiphysics^® 6.0 Release Highlights

Nonlinear Structural Materials Module Updates

For users of the Nonlinear Structural Materials Module, COMSOL Multiphysics^® version 6.0 brings 10x faster creep, performance improvements for many nonlinear materials, anisotropic hyperelastic materials, nonlocal plasticity, and improvements for viscoplastic models. Read more about these updates below.

Anisotropic Hyperelastic Materials

By adding one or more Fiber attributes under a Hyperelastic material, you can augment the stiffness by the effect of distributed fiber bundles. The new attribute includes three material models for fibers: Holzapfel-Gasser-Ogden, Linear Elastic, and User defined. You can see this new feature in the new Biventricular Cardiac Model tutorial model and the existing Arterial Wall Mechanics and Arterial Wall Viscoelasticity models.

Biventricular cardiac model. The fiber directions in the myocardium are used in the Holzapfel-Gasser-Ogden anisotropic hyperelastic material model.

Nonlocal Plasticity

Shear bands or plastic strain localization might occur when modeling plasticity in ductile materials. These zones evolve differently for different mesh sizes. The new Nonlocal Plasticity functionality has been added to the Plasticity and Porous Plasticity features and allows you to obtain a mesh-independent solution when plastic strain localization occurs. You can see this new update in the existing Necking of an Elastoplastic Metal Bar tutorial model.

Creep and Viscoplasticity Improvements

A new general framework for Creep and Anand Viscoplasticity gives large improvements in computational speed and memory usage. For larger models, a speedup by a factor of 10 or more is achieved. The inelastic strain variables are now solved with either a Backward Euler, Forward Euler, or Domain ODEs time-stepping method.

The type of equivalent stress used to determine the creep rate is now a user input. You can select von Mises, Hill Orthotropic, Pressure, or User defined to model nonisotropic creep. When more than one creep mechanism is acting, you can also add one or more Additional Creep nodes under a Creep node. You can see these improvements in the new Creep Analysis of a Turbine Stator Blade and the following existing models:

• combining_creep_material_models
• combining_elastoplastic_and_creep_material_models
• thermally_induced_creep
• primary_creep_under_nonconstant_load
• viscoplastic_creep_in_solder_joints

The Creep feature is used to demonstrate how secondary creep can cause deformation in a turbine stator blade. The creep rate is highly influenced by temperature.

New van der Waals Hyperelastic Material

A new van der Waals hyperelastic material model has been added to model rubber-like materials in solids, shells, and membranes. If the Composite Materials Module is available, the material model can also be used in multilayered shells. This material is sometimes called the Kilian model.

New Inelastic Strain Rate Node

The new Inelastic Strain Rate attribute has a similar effect to the existing External Strain feature, the difference being that you can now specify an inelastic strain rate that is then integrated in time into an inelastic strain contribution. The strain rate can be specified in terms of a strain tensor, a deformation gradient, an inverse deformation gradient, or three orthogonal stretches.

New Reduced Integration Framework

A new framework has been added for reduced integration, including hourglass stabilization. Reduced integration is particularly useful when the computational cost per integration point is high, which is true for many nonlinear material models such as Plasticity or Creep.

Reduced integration is controlled from the new Quadrature Settings section. It is available in the settings for top-level material models like Linear Elastic Material and Nonlinear Elastic Material. The selected reduced integration rule will then be inherited by any subnodes that may be added. You can see this new framework in these existing tutorial models:

• necking_of_an_elastoplastic_metal_bar
• impact_analysis_of_a_golf_ball
• shape_memory_alloy_self_-_expanding_stent

New Tutorial Models

COMSOL Multiphysics^® version 6.0 brings several new tutorial models to the Nonlinear Structural Materials Module.

Two-Stage Powder Compaction Process

Powder compaction is a key process in powder metallurgy, where it gives the flexibility to produce quality products of complex shapes for sintering. The density of the compact is a key factor to determine the overall quality of the product, as regions with lower density could reduce its mechanical strength.

Application Library Title:
two_stage_compaction
Download from the Application Gallery

Pharmaceutical Tableting Process

Powder compaction is a popular manufacturing process in the pharmaceutical industry. The Capped Drucker–Prager model is used for simulating the compaction processes of microcrystalline cellulose.

Application Library Title:
pharmaceutical_tableting_process
Download from the Application Gallery

Creep Analysis of a Turbine Stator Blade

Stress caused by secondary creep in a turbine stator blade. The creep rate is highly influenced by temperature, and the deformation and stress relaxation are thus controlled by the temperature field.

Application Library Title:
turbine_stator_creep
Download from the Application Gallery

Biventricular Cardiac Model

Biventricular cardiac model. The fiber directions in the myocardium are used in the Holzapfel–Gasser–Ogden anisotropic hyperelastic material model.

Application Library Title:
biventricular_cardiac_model
Download from the Application Gallery