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Model body geometries, inertias, colors, and frames

Model the bodies of an articulated mechanical assembly. Bodies can be rigid or flexible, the latter being free to deform when acted upon by a force or torque. All bodies are characterized by their physical properties, among them geometry, inertia, and color. Flexible bodies have the additional properties of stiffness, damping, and discretization level.

Rigid bodies are based on the various solid blocks, the File Solid block, or, in special cases, their equivalents of variable mass and geometry. You can find the latter in the Body Elements > Variable Mass library. Use the File Solid block to import a body from a 3-D part file. Flexible bodies are based on the blocks in the Body Elements > Flexible Bodies library. These include flexible beam blocks, representing slender bodies with specified cross-sections, and the Reduced Order Flexible Solid block, which captures the mechanical behavior of a deformable body through a reduced-order model.

A single Brick Solid, File Solid, or General Flexible Beam block may suffice to completely model a body. More often, several are required. The body is then a composite of simpler body elements fixed to one another. Frame connection lines between the blocks establish the necessary rigid connections between the body elements. Rigid Transform blocks, normally inserted in the connection lines, provide the relative positions and orientations required for proper assembly.


Flexible Body Model BuilderGenerate reduced-order model data for flexible bodies (Since R2023a)


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simscape.multibody.BrickCreate brick geometry (Since R2022a)
simscape.multibody.CylinderCreate cylindrical geometry (Since R2022a)
simscape.multibody.EllipsoidCreate ellipsoidal geometry (Since R2022a)
simscape.multibody.GeneralExtrusionCreate extruded geometry with arbitrary polygonal cross section (Since R2022a)
simscape.multibody.GeometryAbstract base class for geometries (Since R2022a)
simscape.multibody.RegularExtrusionCreate extruded geometry with regular polygonal cross section (Since R2022a)
simscape.multibody.RevolutionCreate revolved geometry (Since R2022a)
simscape.multibody.SphereCreate spherical geometry (Since R2022a)
simscape.multibody.InertiaAbstract base class for specifying mass distributions (Since R2022a)
simscape.multibody.MassDistributionConstruct custom mass distribution (Since R2022a)
simscape.multibody.PointMassConstruct point mass (Since R2022a)
simscape.multibody.UniformMassConstruct uniform mass distribution with given total mass (Since R2022a)
simscape.multibody.UniformDensityConstruct uniform mass distribution with given density (Since R2022a)
simscape.multibody.AdvancedVisualPropertiesSpecify advanced visual properties (Since R2022a)
simscape.multibody.SimpleVisualPropertiesSpecify simple visual properties (Since R2022a)
simscape.multibody.VisualPropertiesAbstract base class for visual properties (Since R2022a)

Simscape Blocks

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Brick SolidSolid brick element with geometry, inertia, and color (Since R2019b)
Cylindrical SolidSolid cylindrical element with geometry, inertia, and color (Since R2019b)
Ellipsoidal Solid Solid ellipsoidal element with geometry, inertia, and color (Since R2019b)
Extruded SolidSolid extruded element with geometry, inertia, and color (Since R2019b)
File SolidSolid with properties derived from CAD file
General Variable MassMass element with variable inertial properties
GraphicMarker with graphic properties
InertiaMass element with fixed inertial properties
Reduced Order Flexible SolidCreate flexible body using reduced-order model data (Since R2019b)
Revolved SolidSolid revolved element with geometry, inertia, and color (Since R2019b)
Spherical SolidSolid spherical element with geometry, inertia, and color (Since R2019b)
Variable Brick SolidSolid brick with variable mass and size
Variable Cylindrical SolidSolid cylinder with variable mass and size
Variable Spherical SolidSolid sphere with variable mass and size
General Flexible PlateThin plate with elastic properties for deformation (Since R2021b)
Flexible Angle BeamAngle beam with elastic properties for deformation (Since R2020a)
Flexible Channel BeamChannel beam with elastic properties for deformation (Since R2020a)
Flexible Cylindrical BeamCylindrical beam with elastic properties for deformation (Since R2020a)
Flexible I BeamI-beam with elastic properties for deformation (Since R2020a)
Flexible Rectangular BeamRectangular beam with elastic properties for deformation (Since R2020a)
Flexible T BeamT-beam with elastic properties for deformation (Since R2020a)
General Flexible BeamSlender extrusion with elastic properties for deformation
DiskDisk for contact modeling (Since R2022a)
Grid SurfaceGrid surface for contact modeling (Since R2021b)
Infinite PlaneInfinite plane for contact modeling (Since R2020b)
Line SegmentLine segment geometry (Since R2023b)
PointPoint geometry for contact modeling (Since R2020b)
Point CloudPoint cloud geometry (Since R2021a)
SplineCubic interpolating plane curve or space curve
Reference FrameNon-inertial reference frame
Rigid TransformFixed spatial relationship between frames
World FrameInertial reference frame


smnewOpen Simscape Multibody model template
sm_libOpen the Simscape Multibody block library



  • Bodies Workflow
    Bodies, the core constituents of a multibody model, comprise body elements, each in turn comprising frames and attributes. Modeling a body is more than adding a block to a model. Here are some general steps to keep in mind when modeling one.
  • Overview of Flexible Beams
    Flexible beams are slender bodies with constant cross-sections that can have linear elastic deformations. Use them when the rigid-body approximation is not valid. Here are some background information to keep in mind when modeling flexible beams.
  • Compounding Body Elements
    A typical body is a collection of solids and other body elements. In this sense, it is a compound unit. Learn how you can use compounding to create complex geometries and inertias from simpler ones.
  • Model an Excavator Dipper Arm as a Flexible Body
    Use the Reduced Order Flexible Solid block to model a deformable body of arbitrary geometry. Start with the CAD geometry of the body, produce a finite-element mesh, and generate reduced-order data to use with the block.
  • Modeling Bodies
    Bodies are representations that you create of physical parts—gears, pistons, levers—for later assembly into multibody systems, a piston engine serving as an example. Here is an introduction to bodies as well as the blocks and tools commonly used to represent one in a model.


  • Modeling Extrusions and Revolutions
    General Extruded Solid and Revolved Solid blocks are the most versatile of the preset solid shapes. Their cross-sections are custom and set by coordinate matrices that you specify. Here is an introduction to both the shapes and the cross-sections that define them.
  • Representing Solid Geometry
    Geometry is a key attribute of solids and of the bodies they comprise. You can specify the shape and size of a solid using the Solid block. Here is an introduction to the types of shapes that you can specify (or import) using this block.


  • Representing Solid Inertia
    Inertia quantifies the resistance of a body to changes in motion and is among the most important attributes in a model. Here is an introduction to the types of inertias that you can represent in a model as well as the blocks and parameterizations that you can use to do so.
  • Specifying Custom Inertias
    "Inertia" is a general term often used to mean mass, center of mass, the moments of inertia, and the products of inertia. Learn more about these inertia parameters and how they are defined in the Simscape Multibody environment.
  • Specifying Variable Inertias
    Not all inertias remain constant during simulation. Some can vary and it is often their changing parameters that most matter in a model. Learn more about variable inertias and how you can specify their parameters in a model.


  • Creating Connection Frames
    Often, you must create new frames for use in joint and constraint connections. Learn how you can create such frames and how joints and constraints affect their placements in a body.
  • Creating Custom Solid Frames
    All solids have a local reference frame but you can create other, custom, frames, for connection in a model. Learn how you can perform this task using the frame creation panel of the Solid block.
  • Working with Frames
    Frames are axis triads that encode the position and orientation of body elements in a body. Learn about frames as a means to connect body elements and about rigid transforms as a means to offset those elements.


  • Manipulate the Color of a Solid
    Color helps to differentiate bodies and contributes to the effectiveness of a multibody visualization. Learn about the color parameters that you can specify and their impact on the appearance of your bodies.
  • Visualize a Model and Its Components
    Visualization is not only a central part of a multibody simulation, but also an essential tool in modeling bodies and verifying their shapes, sizes, frame placements, and colors. Here is an overview of the visualization utilities available in the Simscape Multibody environment and the roles they play in your modeling workflow.