COMSOL Multiphysics^® 6.3 Release Highlights

Structural Mechanics Module Updates

For users of the Structural Mechanics Module, COMSOL Multiphysics^® version 6.3 introduces new multiphysics interfaces for modeling electromechanics in thin structures, a revised contact formulation, and tools for modeling spot welds and fasteners with simplified workflows. Learn more about these updates and other enhancements below.

New Electromechanics Multiphysics Interfaces

The new Electromechanics, Shell and Electromechanics, Membrane interfaces simplify modeling the deformation of thin structures, such as microphone membranes, influenced by electrostatic forces. These interfaces automatically include the Electromechanics, Boundary multiphysics coupling for seamless integration with shell or membrane elements, and they use the Electrostatics interface to model the electric field. Demonstrated in the Brüel & Kjær 4134 Condenser Microphone and Axisymmetric Condenser Microphone tutorial models, these interfaces require the AC/DC Module or MEMS Module in addition to the Structural Mechanics Module.

The COMSOL Multiphysics UI showing the Model Builder with the Electromechanics, Boundary node highlighted, the corresponding Settings window, and a microphone model in the Graphics window.

The new Electromechanics, Boundary multiphysics coupling used in the Brüel & Kjær 4134 microphone model for a simplified model setup when coupling the Electrostatics and Membrane interfaces.

Shrinkage and Swelling Multiphysics Coupling

For modeling volume changes induced by diffusion, a new Shrinkage and Swelling multiphysics coupling that bidirectionally connects the Transport in Solids and Solid Mechanics interfaces has been added. This new coupling can be used to simulate the effects of concentration changes on volume and how stresses may affect diffusion. This is useful, for example, in batteries, where very large volume changes can occur due to ion transport. This new feature can be seen in the following tutorial models:

The COMSOL Multiphysics UI showing the Model Builder with the Shrinkage and Swelling node highlighted, the corresponding Settings window, and a microbattery in the Graphics window.

The Settings window for the Shrinkage and Swelling multiphysics coupling, used to model swelling in a solid-state microbattery.

Simplified Modeling of Fasteners

For structures connected by a large number of fastening elements such as rivets or bolts, manual modeling of each element can become time consuming. To help alleviate this, a new Fasteners feature has been added to the Shell interface. This feature automatically detects paired circular holes on parallel shell boundaries and connects them. The stiffness of the connection will take properties such as material data, fastener diameter, and plate thickness into account. It is also possible to compute safety factors for the fasteners based on user-defined expressions. The new Postbuckling Analysis of an Aircraft Fuselage tutorial model showcases this feature.

The COMSOL Multiphysics UI showing the Model Builder with the Fasteners node highlighted, the corresponding Settings window, and two Graphics windows.

The Settings window for the Fasteners node, the displacement of a postbuckling analysis of a riveted aircraft fuselage, and a close-up view of the fastener forces at the stringer–frame connection.

Spot Welds

For the Shell interface, a new Spot Welds feature has been added that makes it easier to model structures connected by a large number of spot welds. The locations of the weld nuggets are given as a list that can be imported from a text file. The implementation is independent of the mesh on the connected shell boundaries and includes a user-controlled stiffness. The forces and moments transferred by each nugget can also be evaluated in graphic and tabular form. The new Spot-Weld Connection in a Double Hat Beam tutorial model showcases this new feature.

The Settings window for the Spot Welds node and an eigenmode for a spot-welded beam profile.

Contact Formulation for Interior Boundaries

A new Interior Contact feature has been added to the Solid Mechanics interface that makes it possible to include contact conditions such as friction, adhesion, and decohesion to internal boundaries. With this formulation, contact pairs and assemblies are not required and the analysis can be geometrically linear. This feature can be used for modeling applications such as bolted joints and boundaries separated by decohesion. The Mixed-Mode Debonding of a Laminated Composite and Vibration of a Squeezed Plate tutorial models have been updated to showcase this new feature.

The COMSOL Multiphysics UI showing the Model Builder with the Interior Contact node highlighted, the corresponding Settings window, and a bolted joint model in the Graphics window.

The Settings window for the Interior Contact node, used to model a bolted joint under load.

Fitting of Viscoelastic Data

Properties for viscoelastic materials are often measured in the frequency domain and are typically available as frequency-dependent storage and loss moduli or approximated using fractional derivative models. In this version, a new capability has been added to the Viscoelasticity feature that maps such data to time-domain functions using a partial fraction fit. This allows users to perform time-dependent simulations of viscoelastic materials, regardless of the original form of the material properties. This new addition can be seen in the Eigenmodes of a Viscoelastic Structural Damper tutorial model.

The COMSOL Multiphysics UI showing the Model Builder with the Viscoelasticity node highlighted, the corresponding Settings window, and a 1D plot in the Graphics window.

The Settings window for the viscoelastic data fitting and a preview graph showing a comparison of the fit to the source data for storage and loss moduli.

Visualization of 3D Beams and Pipes

It is now possible to achieve a full 3D visualization for beam and pipe elements using the new Beam and Pipe dataset types. These datasets can be used, for example, to visualize stress distribution and variables over the cross section. The built-in cross section types, Rectangle, Circular, Box, Pipe, H-profile, T-profile, U-profile, C-profile, and Hat, are supported. The following tutorial models showcase this new capability:

A joint in a frame, visualized using the new Beam dataset.

Stabilization in the Membrane Interface

The out-of-plane stiffness for membranes is controlled by the in-plane tension. As an effect, it is common that membranes are numerically unstable in an initial stress-free configuration, before external loads have been added. With the new Stabilization feature in the Membrane interface, it is possible to achieve automatic stabilization during the first few iterations before the structure has obtained its correct physical and numerical stiffness from the induced loading. The following tutorial models demonstrate this feature:

The COMSOL Multiphysics UI showing the Model Builder with the Stabilization node highlighted, the corresponding Settings window, and an airbag model in the Graphics window.

The settings for the new Stabilization node with an inflated membrane structure in the Graphics window.

Random Particulate Composite Add-In

A new add-in to generate geometry parts for random particulate composites has been added under the COMSOL Multiphysics branch of the Add-in Libraries. The add-in can be used to create spherical particles inside a rectangular block, where their positions and size are fixed or randomly distributed based on different probability distributions.

The COMSOL Multiphysics UI showing the Model Builder with the Random Particulate Composite RVE node highlighted, the corresponding Settings window, a cube geometry part in the Graphics window, and a histogram.

The Random Particulate Composite RVE add-in shown in the Model Builder, the created geometry part, and a the histogram plot.

Composites Material Library Folder

The new built-in folder for Composites is divided into three groups of materials: fiber constituents, matrix constituents, and laminae. This feature makes it easier to set up models with common types of composite plies. You can view these new materials being used in the following tutorial models: