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 tailored for analyzing mechanical behavior of solid structures. The module provides you with modeling tools and functionality for solid mechanics, dynamics and vibrations, materials modeling, shells, beams, contact, fractures, and more. Application areas include mechanical engineering, civil engineering, geomechanics, biomechanics, and MEMS devices.

The Structural Mechanics Module brings 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; further extend your modeling to include 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, you will be able to answer 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
  • Response spectrum
  • Random vibration

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 closeup view of two bracket models showing the original geometry and final optimized geometry.
Optimization

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 the various types of structural analyses. Based on the finite element method, 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 and cables, and transitions between all these different formulations.

For 3D solids modeling, there are many options for the element shapes and orders. Triangle, quad, tet, hex, prism, and pyramid elements are all available. 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 closeup 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); and 2D axial symmetry, and provide the most general approach to analyzing solid structures with built-in multiphysics couplings to a large number of physics areas. There is a wide variety of material models available for accurately describing your solid mechanics problem, and it is easy to extend these features via equation-based modeling. Define material properties yourself 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.

A closeup view of the Solid-Shell Connection settings and a bracket 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. You can prescribe an offset in the direction normal to a selected surface, which simplifies modeling where you work with 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 closeup 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 is dedicated to transient linear elastic waves propagation problems 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 closeup 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, but you can also access a wide range of nonlinear material models, including hyperelastic and elastoplastic, by adding the Nonlinear Structural Materials Module or Geomechanics Module.

In addition, there are many possibilities to extend the existing material models or create your own. Enter expressions that depend on stress, strain, spatial coordinates, time, or fields coming from another physics interface directly in the input field for a material property. In frequency-domain analyses, you can enter complex-valued expressions. You can, for example, add custom differential equations to provide inelastic strain contributions.

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

A closeup 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 provides you with a multitude of different loads and constraints options, which facilitates high-fidelity modeling. Define distributed loads on domains, boundaries, and edges, follower loads, and moving loads. Specify a total force, include gravity or added mass, and include rotating frames with centrifugal, Coriolis, and Euler forces.

For constraining the 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 closeup 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 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 the structural response to short nondeterministic events like earthquakes and shocks.

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

Beams, Pipes, and Trusses

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 the capability of modeling general cross sections.

Additionally, the Structural Mechanics Module enables you to model slender structures that can only sustain axial forces (trusses). These elements can also be used for modeling sagging cables and 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, 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 closeup 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 closeup view of the Damage settings and a notched beam model in the Graphics window.

Fracture Mechanics

Several different approaches to 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.

J-integrals and stress intensity factors can be computed in 2D and 3D. You can also prescribe a load on the crack faces.

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

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

Engineering Features

In the Structural Mechanics Module, you will find several structural engineering features that help you create 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
  • Safety factor expressions
  • Computation of section forces in a cut through a solid
  • Load cases
  • 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 your 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, plus it lets you perform the following 3D CAD operations: loft, fillet, chamfer, midsurface, and thicken.

Choose from a line of interfacing products, known as LiveLink™ products, with which you can synchronize the CAD-native model for use in the COMSOL® software. You can also simultaneously update geometry parameters in both the CAD system and COMSOL Multiphysics®, as well as perform parametric sweeps and optimization 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 closeup 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 closeup 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 closeup 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 closeup 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 closeup view of a piezoelectric actuator model showing the deformation and tip deflection.

Piezoelectricity

Piezoelectric devices including metallic and dielectric components.

A closeup 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 closeup view of a multilateral well model showing the displacement magnitude.

Poroelasticity4

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

A closeup view of a pressure sensor model showing the displacement magnitude.

Hygroscopic Swelling

Absorption of moisture and hygroscopic swelling in polymers and batteries.

A closeup view of a micromirror model showing the deformation and mesh volume.

MEMS5

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

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

Electromagnetic Materials6

Magnetostrictive, electrostrictive, and ferroelectric elastic devices.

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

Stress-Optical Effects8

Stress-induced birefringence in waveguides.

A closeup view of a Petzval lens model showing the rays at three different angles.

STOP Analysis9

Structural-thermo-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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