Nonlinear Structural Materials Module Updates

For users of the Nonlinear Structural Materials Module, COMSOL Multiphysics® version 5.6 brings plasticity and damage improvements, as well as new hyperelastic material models. Browse these features and more below.

Plasticity Improvements

A new node, Set Variables, is available as an attribute under the Plasticity and Porous Plasticity nodes in the Solid Mechanics, Shell, Layered Shell, Membrane, and Truss interfaces. This feature makes it possible to assign values or expressions to plastic variables based upon Boolean conditions, for both the Small plastic strains and Large plastic strains options. You can see this functionality demonstrated in the Plastic Strain Mapping model.

The COMSOL Multiphysics version 5.6 UI with the Set Variables node settings shown and a meshed model shown to the right. Demonstrating the Set Variables node Mapping of plastic strains from a triangular mesh in Component 1 to the quadrilateral mesh in Component 2 using the Set Variables node.

Large-Strain Plasticity in Layered Shell Interface

The Linear Elastic Material in the Layered Shell interface now includes the possibility to model Large-Strain Plasticity. The same set of yield functions and isotropic hardening models as in the Solid Mechanics interface are available.

It is now possible to add Plasticity to the Hyperelastic Material node in the Layered Shell interface. The new subnode uses the Large-Strain Plasticity formulation. The same set of yield functions and isotropic hardening models are available as in the Hyperelastic Material node for the Solid Mechanics interface. The Layered Shell interface requires the Composite Materials Module.

Porous Plasticity Improvements

The Large plastic strains option is available to all the material models under the Porous Plasticity node. The formulation uses a multiplicative decomposition of deformation gradients, giving a good approximation at high compressive strains. You can see this functionality demonstrated in the Powder Compaction of a Flanged Component model. Also, the Capped Drucker-Prager model is available as an attribute under the Linear Elastic Material and Nonlinear Elastic Material nodes.

The COMSOL Multiphysics version 5.6 UI with the Porous Plasticity settings shown with the Porous Plasticity section expanded and a rotational flange model in the Graphics window. Demonstrating the Porous Plasticity settings The Porous Plasticity node settings in COMSOL Multiphysics® version 5.6 with the Large plastic strain option and the Capped Drucker-Prager material model selected.

Nonlinear Elastic Material Improvements

A new material model called Shear data is added to the Nonlinear Elastic Material node. The new material model is similar to the Uniaxial data model, but it is intended for simulations where shear stress vs. shear angle data is available. In the Uniaxial data material model, the Hardening data can now be taken from the Material Library.

Viscoelasticity Improvements

Two more built-in viscoelastic models are added to the Nonlinear Elastic Material: the Maxwell and Generalized Kelvin models. For frequency domain analyses, you can add fractional derivatives for all the built-in viscoelastic models.

When using a Viscoelasticity subnode under the Hyperelastic Material node, a new leaner implementation for the Generalized Maxwell and Standard Linear Solid models for large-strain viscoelasticity is available, giving significant speedups. You can see this functionality demonstrated in the Impact Analysis of a Golf Ball model.

New Hyperelastic Material Models

Three new hyperelastic material models are added: the Extended Tube model for modeling rubber-like materials, and the Delfino and anisotropic Fung material models to simulate large deformations in biological tissue. Additionally, all of the Hyperelastic Material models available in the Solid Mechanics interface are now available in the Layered Hyperelastic Material node in the Shell interface. If the Composite Materials Module is available, the material models can also be used in multilayered shells, and the individual layers can have different material models.

The COMSOL Multiphysics version 5.6 UI with the Hyperelastic Material model settings shown and a sea urchin blastula model in the Graphics window. The hyperelastic Delfino material model is used for a sea urchin blastula A spherical sea urchin blastula modeled with the new hyperelastic Delfino material model. The plot shows the ratio between the deformed and undeformed radius for varying internal pressure and different material parameters.

Nonlinear Material Models in the Layered Shell Interface

The Linear Elastic Material node in the Layered Shell interface now includes the possibility to model Large Strain Plasticity. You can also add Plasticity to the Hyperelastic Material node in the Layered Shell interface. The Plasticity subnode uses the Large Strain Plasticity formulation, which gives a good approximation for high strain levels. Note that both the Nonlinear Structural Materials Module and Composite Materials Module are needed for this functionality. If the Composite Materials Module is available, the material models can also be used in multilayered shells.

Damage in Layered Shells

All the Damage models available in the Solid Mechanics interface are now available for the Layered Linear Elastic Material node in the Shell interface, as well as for the Linear Elastic Material node in the Layered Shell interface. The Layered Shell interface requires the Composite Materials Module.

Damage Improvements

There are several improvements to the Damage feature including a new phase-field-based damage model for crack propagation. The news includes:

  • New viscous regularization method for time-dependent analysis
  • Polynomial strain softening and Multilinear strain softening available for the damage evolution laws for Scalar damage and Mazars damage for concrete
  • New Phase field damage model, available in the Linear Elastic Material node in the Solid Mechanics interface
  • Damage feature available in the Layered Linear Elastic Material node of the Shell interface
  • Damage feature available in the Linear Elastic Material node of the Layered Shell interface
  • A new model: Brittle Fracture of a Holed Plate
Evolution of the crack phase field during loading of a holed plate.

Shape Memory Alloy Improvements

There are several improvements to the Shape Memory Alloy feature:

  • The user inputs for the Shape Memory Alloy material models are now available as material properties
  • For the Lagoudas model, you can enter the material data in terms of transition temperatures or transition stresses
  • The Souza–Auricchio model is modified to account for the reference temperature instead of the martensite finish temperature
  • The radius of the elastic domain is entered instead of the initial yield stress
  • Both the Lagoudas and Souza–Auricchio SMA models are now available in the Truss interface

New Default Plots

New default contour plots, showing the inelastic strains, have been added for the Plasticity, Porous Plasticity, Viscoplasticity, Creep, Viscoelasticity, and Shape Memory Alloy features. Many of the Application Library models reflect this change.

A gray snap hook model with a contour plot for equivalent plastic strain, Gauss point evaluation. A snap hook model with the new default contour plot New default contour plot for equivalent plastic strain.

New Tutorial Models

COMSOL Multiphysics® version 5.6 brings several new tutorial models to the Nonlinear Structural Materials Module.

Impact Analysis of a Golf Ball

A golf club is hitting a golf ball and the inside of the ball is shown with a rainbow color table visualizing the compressive strain. Golf ball model Impact of a golf ball. The plot shows the compressive strain in the core of the ball.

Application Library Title:

golf_ball_impact

Download from the Application Gallery

Brittle Fracture of a Holed Plate

A plate model with three holes shown at four different times; a crack forms and gets larger from left to right. Holed plate model Evolution of the crack phase field during loading of the holed plate.

Application Library Title:

holed_plate_fracture

Download from the Application Gallery

Plastic Strain Mapping

Two meshed versions of an elastoplastic plate shown in a rainbow color table. Elastoplastic plate model with plastic strain mapping Distribution of von Mises stress in an elastoplastic plate with results mapped between two meshes.

Application Library Title:

plastic_strain_mapping

Download from the Application Gallery

Inflation of a Spherical Rubber Balloon — Shell and Membrane Version

A 1D plot of inflation pressure over applied stretch for different material models, where red shows Neo-Hookean, green Mooney-Rivlin, blue Ogden, and magenta Varga. Material model comparison for the inflation of a balloon Comparison of different material models for simulating the inflation of a balloon, for both the Membrane and Shell interfaces.

Application Library Title:

balloon_inflation_membrane

Download from the Application Gallery

Powder Compaction of a Rotational Flanged Component

A rotational flanged component model with a metal sheen and showing displacement magnitude in a rainbow color table. Rotational flanged component model Deformed configuration of the manufactured component, using the Large plastic strains option.

Application Library Title:

compaction_of_a_rotational_flange

Download from the Application Gallery