Deformable Body¶

Learning Objectives¶

After completing this tutorial, you will have learned:

How to enable the Deformable Body (Beta) feature in Isaac Sim
How to create a deformable object (Volume Deformable) from a primitive mesh
How to import external meshes (STL/OBJ, etc.) and create deformable objects
The difference between Volume Deformable and Surface Deformable
How to create and apply a Deformable Body Material

Getting Started¶

Prerequisites¶

Complete Tutorial 7: Adding Props before starting this tutorial.

Estimated Time¶

Approximately 15-20 minutes.

Overview¶

In the previous tutorials, we worked with rigid bodies. Rigid bodies are objects whose shape never changes regardless of how much force is applied. However, in the real world, there are many objects that deform under force, such as sponges, cloth, and rubber products.

Isaac Sim provides the Deformable Body (Beta) feature to simulate such deformable objects. There are two main types of deformable objects:

Type	Description	Examples
Volume Deformable	Solid, closed (watertight) objects with thickness	Sponges, rubber blocks, organ models, etc.
Surface Deformable	Thin membranes or surface-only objects	Cloth, paper, thin sheets, etc.

Beta Feature

Deformable Body is a Beta feature. Its specifications may change in future versions.

Preparation: Enabling the Deformable Feature¶

To use Deformable Body, you first need to enable the feature in Isaac Sim's settings. This only needs to be done once.

Open Edit > Preferences from the top menu.
In the Physics > General section, turn on Enable Deformable schema Beta (Requires Restart).
Restart Isaac Sim.

Visualizing Deformable Meshes (Recommended)

When working with deformable objects, it is helpful to visualize the simulation and collision meshes to verify that the mesh density is appropriate. Click the Eye icon in the viewport and select Show By Type > Physics > Deformables (beta) > All.

Setting Up the Stage¶

Create a new stage and prepare it for physics simulation.

Create a new stage with File > New.
From the top menu, select Create > Physics > Ground Plane to add a ground plane.
Select Create > Physics > Physics Scene to add a physics scene (some templates may already include one).
Select the created PhysicsScene in the Stage window and configure the following settings in the Properties panel:
- Turn on Enable GPU Dynamics
- Set Broadphase Type to GPU

GPU Settings Are Required

Deformable Body is processed through the PhysX GPU pipeline. The simulation will not work correctly if GPU Dynamics is disabled. Make sure to configure the settings above.

Pattern 1: Creating a Deformable Object from a Primitive Mesh¶

The most basic approach is to create a deformable object using Isaac Sim's primitive mesh (Cube).

Step 1: Creating an Xform and Mesh¶

First, create the root Xform for the deformable object and a sufficiently subdivided mesh.

Right-click in the Stage window and select Create > Xform. Rename it to DeformPlate (e.g., /World/DeformPlate).
From the top menu, select Create > Mesh > Settings to open the Mesh Settings dialog.
Set Primitive Type to Cube.
Increase the U/V/W Verts Scale values (e.g., 10 to 30).

About Mesh Subdivision

If the subdivision count is too low, deformation will not be visually noticeable. Start with values around 10-30. You can fine-tune the values with Ctrl + left-click.
Click the Create button to generate the mesh.
Drag-and-drop the generated mesh as a child of /World/DeformPlate.

Step 2: Applying Volume Deformable¶

Apply deformable physics properties to the created mesh.

Select the root Xform (/World/DeformPlate).
Right-click and select Create > Physics > Deformable (beta) > Volume.
A dialog will appear. If needed, turn on Hexahedral Simulation Mesh (to generate a separate simulation mesh for improved stability).
Click the Create button.

Step 3: Testing the Result¶

Select /World/DeformPlate and set the Translate Z value to approximately 1.0 to 2.0 in the Properties panel to raise it above the ground.
Press the PLAY button to start the simulation.

Result: The deformable object falls to the ground and deforms upon collision.
Press the STOP button to stop the simulation.

Pattern 2: Creating a Deformable Object from an External Mesh¶

You can create deformable objects with arbitrary shapes by importing external mesh files such as STL/OBJ/FBX.

Step 1: Importing the Mesh¶

To use an external mesh in Isaac Sim, you first need to convert it to USD format.

From the top menu, select File > Import and use the CAD Converter to import the mesh file. The following images and videos use a sample file.

Checking the Scale

STL files often do not contain unit information. After importing, always verify the scale (in meters).

Step 2: Selecting and Applying the Deformable Type¶

Choose between Volume Deformable or Surface Deformable depending on the shape of the imported mesh.

For Solid, Closed Shapes → Volume Deformable¶

Use Volume Deformable when the mesh is a closed solid shape (watertight).

Right-click in the Stage window and select Create > Xform (e.g., /World/DeformMesh).
Drag-and-drop the imported mesh as a child of the Xform.
Select the Xform, right-click, and select Create > Physics > Deformable (beta) > Volume.
If needed, specify the target mesh in the Source Mesh field of the dialog.

About Source Mesh

You can specify a Source Mesh separate from the rendering mesh for generating the simulation mesh. The Source Mesh can be a mesh located outside the Deformable subtree.
Click the Create button.
Raise the object in the Z direction and press PLAY to verify the behavior.

For Thin Membranes or Surface-Only Shapes → Surface Deformable¶

Use Surface Deformable when the mesh represents a thin sheet or membrane that is not closed.

Select the Xform, right-click, and select Create > Physics > Deformable (beta) > Surface.

Troubleshooting¶

If deformation is not visible or the simulation is unstable, check the following:

Insufficient input mesh resolution: If the mesh has too few vertices, deformation will not be reflected visually. Increase the mesh subdivision count.
Resolution mismatch between simulation and collision meshes: If the resolutions differ significantly, convergence issues are more likely to occur.

Configuring Deformable Body Material¶

The physical properties of deformable objects (stiffness, elasticity, etc.) are controlled by creating and assigning a Deformable Body Material.

Step 1: Creating a Physics Material¶

From the top menu, select Create > Physics > Physics Material.
In the dialog that appears, select Deformable Body Material and click OK.

Step 2: Setting Parameters¶

Adjust the following parameters in the Properties panel of the created physics material:

Parameter	Description
Young's Modulus	Determines the stiffness of the object. Higher values make it stiffer
Poisson's Ratio	The ratio of lateral contraction when the object is stretched (typically 0 to 0.5)
Density	Mass density of the object (kg/m³)
Dynamic Friction	The strength of friction when the object is in motion

Parameter Effects

Density, Young's Modulus, and Poisson's Ratio primarily affect the simulation mesh, while friction coefficients primarily affect the collision mesh.

Step 3: Assigning the Material¶

Select the deformable object (the Deformable root Xform or related Prim).
In the Properties panel, select the created Deformable Body Material from the Physics Materials on Selected … section to assign it.
Press the PLAY button to verify the behavior.

Summary¶

This tutorial covered the following topics:

Enabling the Deformable Body (Beta) feature
Creating a Volume Deformable from a primitive mesh
Importing external meshes and choosing between Volume / Surface Deformable
Configuring and assigning physics parameters with Deformable Body Material

Difference from Rigid Bodies

Rigid bodies are computationally efficient because their shape does not change. Deformable objects, on the other hand, require individual calculations for each mesh vertex, resulting in higher computational cost. Choose between rigid bodies and deformable objects depending on the purpose of your simulation.