Structural Mechanics Module

Run Mechanical Analyses with Extensive Multiphysics Capabilities

The Structural Mechanics Module, an add-on to the COMSOL Multiphysics® platform, is an FEA software package specialized for analyzing mechanical behavior of solid structures. The module includes modeling features and functionality for solid mechanics and materials modeling and the modeling of dynamics and vibrations, shells, beams, contact, fractures, and more. Application areas include mechanical engineering, civil engineering, geomechanics, biomechanics, and MEMS devices.

The Structural Mechanics Module offers built-in multiphysics couplings that include thermal stress, fluid–structure interaction, and piezoelectricity. Combining with other modules from the COMSOL product suite allows for advanced heat transfer, fluid flow, acoustic, and electromagnetics effects and enables specialized materials modeling and CAD import functionality.

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A tube connection model showing the stress at a bolt in the Rainbow color table.

Run a Variety of Structural Analyses

Several analysis types are available for predicting structural performance in a virtual environment. Using the Structural Mechanics Module allows for answering questions concerning stress and strain levels; deformations, stiffness, and compliance; natural frequencies; response to dynamic loads; and buckling instability, to name a few.

Structural Mechanics Module Analyses

  • Static
  • Eigenfrequency
    • Undamped
    • Damped
    • Prestressed
  • Transient
    • Direct or mode superposition
  • Frequency response
    • Direct or mode superposition
    • Prestressed
  • Geometric nonlinearity and large deformations
  • Mechanical contact
  • Buckling and postbuckling
  • Response spectrum
  • Random vibration
  • Component mode synthesis

Generalized Analyses

A 1D plot of a parametric analysis with the displacement on the y-axis and force direction on the x-axis.
Parametric Analysis

Compute a model with multiple input parameters to compare results.

A close-up view of two bracket models showing the original geometry and final optimized geometry.

Optimize geometric dimensions, shape, topology, and other quantities with the Optimization Module.

Finite Elements

The Structural Mechanics Module provides a full suite of modeling tools for various types of structural analyses. Based on the finite element method (FEM), there is functionality not only for modeling 3D solids, but also 2D formulations (plane stress, plane strain, generalized plane strain, and axial symmetry). Similarly, there is functionality for shells and plates, membranes, beams, pipes, trusses, wires, and transitions between all these different formulations.

There are many options for the element shapes and orders. Triangle, quadrilateral, tetrahedron, hexahedron, prism, and pyramid elements are all available. Users can choose from first-, second-, and higher-order elements and, for multiphysics analysis, mixed-order elements.

Features and Functionality in the Structural Mechanics Module

The Structural Mechanics Module provides specialized features and functionality for running a variety of structural analyses and works seamlessly in the COMSOL Multiphysics® platform for a consistent model-building workflow.

A close-up view of the Model Builder with the Solid Mechanics node highlighted and a tube connection model in the Graphics window.

Solid Mechanics

The options for modeling solid mechanics include full 3D; 2D (plane stress, plane strain, and generalized plane strain); 2D axial symmetry; 1D (plane stress or plane strain in transverse directions); and 1D axial symmetry, and provide the most general approach to analyzing solid structures with built-in multiphysics couplings. There is a wide variety of material models available for accurately describing solid mechanics problem, and it is easy to extend these features via equation-based modeling. Users can define material properties with constant, spatially varying, anisotropic, or nonlinear expressions; lookup tables; or combinations of these. Elements can be activated and deactivated based on user-defined expressions. It is also possible to assign material models to surfaces, internal or external. This can be used to model, for example, glue layers, gaskets, fracture zones, or claddings.

A close-up view of the Shell settings and a ladder frame model in the Graphics window.

Shells and Membranes

For thin structures, using shell (3D, 2D axisymmetry) and plate (2D) elements can be very efficient. The formulations allow for the transverse shear deformations needed to model thick shells. It is also possible to prescribe an offset in the direction normal to a selected surface, which simplifies modeling projects involving a full 3D representation of the geometry. The results from shell element analyses can be presented as a full solid representation.

Very thin structures, such as thin films and fabric, require a formulation with no bending stiffness. This is possible in the Membrane interface, in which curved plane stress elements in 3D or 2D axisymmetry are used to compute in-plane and out-of-plane displacements, including the effects of wrinkling. When studying this type of structure, the ability to start from a prestressed state is used extensively.

A close-up view of the Model Builder with the Elastic Waves, Time Explicit node highlighted and an Earth model in the Graphics window.

Elastic Waves

Model the propagation of elastic waves in isotropic, orthotropic, anisotropic, and piezoelectric solids, for single-physics or multiphysics applications, such as vibration control, nondestructive testing (NDT), or mechanical feedback. Application areas range from micromechanical problems to seismic wave propagation.

The Solid Mechanics interface uses a full structural dynamics formulation that accounts for the effects of shear waves and pressure waves in solids and analyzes elastic waves. Mechanical port conditions can be used to excite and absorb propagating modes in waveguide structures and to compute a scattering matrix of a component. Absorbing boundary conditions and perfectly matched layers (PMLs) enable efficient modeling of unbounded domains.

The Elastic Waves, Time Explicit interface can be used to compute the transient propagation of linear elastic waves over large domains containing many wavelengths. The interface uses a higher-order dG-FEM time-explicit method. The interface is multiphysics enabled and can be seamlessly coupled to fluid domains.

A close-up view of the Viscoelasticity settings and a damper model in the Graphics window.

Material Models

The Structural Mechanics Module provides linear elastic, viscoelastic, and piezoelectric material models, and a wide range of nonlinear material models, including hyperelastic and elastoplastic models, is accessible by adding the Nonlinear Structural Materials Module or Geomechanics Module.

In addition, there are many possibilities for extending the existing material models or for users to create their own. Expressions that depend on stress, strain, spatial coordinates, time, or fields coming from another physics interface can be entered directly in the input field for a material property. In frequency-domain analyses, complex-valued expressions can be entered. For example, custom differential equations can be added to provide inelastic strain contributions.

The material models can accommodate thermal expansion, hygroscopic swelling, initial stresses and strains, and several types of damping. Material properties can be isotropic, orthotropic, or fully anisotropic. Users can include their own material model by providing external functions coded in the C programming language.

A close-up view of the Model Builder with the Boundary Load node highlighted and a 1D plot in the Graphics window.

Loads and Constraints

The Structural Mechanics Module offers a multitude of different load and constraint options, which facilitates high-fidelity modeling. There are capabilities for defining distributed loads on domains, boundaries, and edges, follower loads, and moving loads. There is also support for specifying a total force, including gravity or added mass, and including rotating frames with centrifugal, Coriolis, and Euler forces.

For constraining a model, there are springs and dampers, as well as prescribed displacement, velocity, and acceleration. Periodic boundary conditions, low-reflecting boundaries, perfectly matched layers (PMLs), and infinite elements aid in reducing model size for efficient modeling.

A close-up view of the Model Builder with the Displacement node highlighted and a steel frame model in the Graphics window.

Dynamics and Vibration

The Structural Mechanics Module covers transient as well as frequency-response analysis. Frequency-response analysis includes eigenfrequency, damped eigenfrequency, and frequency sweep analyses. In addition, specialized study types are available for random vibration and response spectrum analysis. Random vibration analysis allows for inputs based on power spectral density (PSD) as a function of frequency, including uncorrelated as well as fully correlated loads. A typical example is the wind load on a tower. Response spectrum analysis is used as an efficient method for determining structural response to short nondeterministic events like earthquakes and shocks.

Component mode synthesis (CMS), also known as dynamic substructuring, reduces linear components to computationally efficient reduced-order models using the Craig–Bampton method. These components can then be used in dynamic or stationary analyses, improving computation time and memory usage.

A close-up view of the Model Builder with the Cross-Section Data node highlighted and a truss tower model in the Graphics window.

Beams, Pipes, Trusses, and Wires

There are specialized element types for modeling beams, described by their cross section properties. Formulations for both slender beams (Euler–Bernoulli theory) and thick beams (Timoshenko theory) are available. Predefined couplings allow for mixing beams with other element types to study reinforcements for solid and shell structures. A library of common cross section types are available as well as functionality for modeling general cross sections.

Additionally, the Structural Mechanics Module enables the modeling of slender structures that can only sustain axial forces (trusses and wires). These elements can also be used for modeling reinforcements.

Structural analysis of pipes is similar to that of beams but with the addition of an internal pressure that usually contributes significantly to the stresses in a pipe. Also, in this type of analysis, temperature gradients usually occur through the pipe wall, rather than across the entire section. The loads from internal pressure and drag forces can be taken directly from the results of a pipe flow and thermal analysis using the Pipe Flow Module.

A close-up view of the Contact settings and an arch model in the Graphics window.

Contact and Friction

Situations where objects come into contact with each other occur frequently in mechanical simulations. Static and dynamic analyses can include contact modeling, and the objects in contact can have arbitrarily large relative displacements. Additionally, the effects of friction, both sticking and sliding, can be modeled.

The contact analysis functionality also includes the possibility to prescribe adhesion and decohesion between the contacting objects, and to model removal of material by wear when the objects are sliding relative to each other.

A close-up view of the Damage settings and a notched beam model in the Graphics window.

Fracture Mechanics

Several different approaches for crack modeling are supported. A crack can either be infinitely thin and represented by a single boundary or represented by disjoint surfaces in the geometry. A crack can have any number of branches and corresponding crack fronts. Effects of crack closure, as well as loads on the crack faces, can be included. Stress intensity factors and energy release rates can be computed in 2D and 3D using J-integral or virtual crack extension methods.

By adding the Nonlinear Structural Materials Module or Geomechanics Module, users can model damage and cracking in brittle materials according to various criteria.

A close-up view of the Bolt Thread Contact settings and a bearing cap model in the Graphics window.

Engineering Features

The Structural Mechanics Module, includes several structural engineering features that allow for creating real-world models more quickly. These features include boundary conditions such as rigid connectors for modeling rigid regions and kinematic constraints, bolts with pretension, stress linearization for analysis of pressure vessels, and more.

  • Rigid connector
  • Rigid domain
  • Automatic handling of RBE2 elements from NASTRAN® import
  • Bolt pretension
  • Bolt thread contact modeling
  • Stress linearization
  • Weld evaluation
  • Evaluation of warpage
  • Safety factor expressions
  • Computation of section forces in a cut through a solid
  • Superposition of load cases
  • Computation of effective material properties
    • Uses representative volume elements (RVE)

Add-On Modules to the Structural Mechanics Module

Specialized analyses, completely integrated with the COMSOL Multiphysics® software environment.

The Nonlinear Structural Materials Module and the Geomechanics Module extend the functionality of the Structural Mechanics Module with more than 100 different nonlinear material models.

Add the Composite Materials Module to analyze thin, layered structures (composite materials), such as fiber-reinforced plastic, laminated plates, and sandwich panels found in aircraft components, wind turbine blades, automobile components, and more.

Add the Fatigue Module to compute the fatigue life of structures: high-cycle fatigue, based on stress, and low-cycle fatigue, based on strain or energy. There is functionality for rainflow cycle counting, cumulative damage, and multiaxial and vibration fatigue.

Add the Rotordynamics Module to model rotating machines where asymmetries can lead to instabilities and damaging resonances. Build rotor components with disks, bearings, and foundations, and analyze the results with Campbell diagrams, orbits, waterfall plots, and whirl plots.

Import Designs from Third-Party CAD Software

Choose from a number of interfacing products to connect with COMSOL Multiphysics®.

Import a variety of industry-standard CAD formats into COMSOL Multiphysics® for simulation analysis using the CAD Import Module. Available features include options to repair and clean up CAD geometry to prepare it for meshing and analysis, as well as access to the Parasolid® geometry kernel for advanced solid options. The Design Module also includes these features, and it supports the following 3D CAD operations: loft, fillet, chamfer, midsurface, and thicken.

Choose from a line of interfacing products, known as LiveLink™ products, with which the CAD-native model can be synchronized for use in the COMSOL® software. In addition, geometry parameters in both the CAD system and COMSOL Multiphysics®, and parametric sweeps and optimization can be performed over several different modeling parameters.

Multiphysics Couplings for Extended Structural Mechanics Analyses

Easily combine two or more physics interactions, all within the same software environment.

A close-up view of the temperature field of a turbine stator model.

Thermal Stress

Thermal stress and expansion, with a given or computed temperature field, in solids and shells.

A close-up view of a multiphysics example of modeling aluminum extrusion accounting for FSI and thermal stresses.

Fluid–Structure Interaction (FSI)

One-way or two-way couplings between a fluid and solid structure, including both fluid pressure and viscous forces.

A close-up view of the residual stresses of a spur gear model.

Metal Processing1

Stresses and strains of phase-composition-dependent materials during steel quenching and other heat treatment processes.

A close-up view of the differential gear mechanism of a model.

Multibody Dynamics2

An extensive set of tools for simulating mixed systems of flexible and rigid bodies.

A close-up view of a piezoelectric actuator model showing the deformation and tip deflection.


Piezoelectric devices including metallic and dielectric components.

A close-up view of a piezoacoustic transducer model showing the acoustic pressure.

Acoustic–Structure Interaction3

Solid–acoustic, acoustic–shell, and piezo–acoustic interactions, as well as vibration and elastic wave propagation.

A close-up view of a multilateral well model showing the displacement magnitude.


Porous media flow coupled with solid mechanics to model poroelastic effects.

A close-up view of a pressure sensor model showing the displacement magnitude.

Hygroscopic Swelling

Absorption of moisture and hygroscopic swelling in polymers and batteries.

A close-up view of a micromirror model showing the deformation and mesh volume.


Piezoresistivity, electromechanical deflection due to electrostatic forces, and electrostriction.

A close-up view of a magnetostrictive transducer model showing the stress, displacement, and magnetic field.

Electromagnetic Materials6

Magnetostrictive, electrostrictive, and ferroelectric elastic devices.

A close-up view of a heating circuit model showing the stress and deformation.

Low-Frequency Electromagnetics6

Deformations in electronic devices and electric motors due to electromagnetic forces.

A close-up view of a cavity filter model showing the temperature and thermal stresses.

RF and Microwave Components7

Mechanical deformation and stress affecting the performance of RF and microwave devices and components such as filters.

A close-up view of a photonic waveguide showing the stress-optical effect.

Stress-Optical Effects8

Stress-induced birefringence in waveguides.

A close-up view of a Petzval lens model showing the rays at three different angles.

STOP Analysis9

Structural-thermal-optical performance (STOP) analysis on optical systems.

  1. Requires the Metal Processing Module
  2. Requires the Multibody Dynamics Module
  3. Requires the Acoustics Module
  4. Requires the Porous Media Flow Module or Subsurface Flow Module
  5. Requires the MEMS Module
  6. Requires the AC/DC Module
  7. Requires the RF Module
  8. Requires the Wave Optics Module
  9. Requires the Ray Optics Module

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