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Documentation

SimScale DocumentationSimulation SetupBoundary ConditionsDistributed Mass

Distributed Mass

The Distributed Mass boundary condition enables the user to account for the mass distribution of secondary parts not geometrically added in the model, but which might still influence the kinematic behavior of the primary parts represented in the model. This is particularly useful in scenarions where additional mass needs to be accounted for in structural analysis. The extra mass will be applied over a surface and may be defined in two different ways:

Distributed Mass BC. Different ways to set it up.
Figure 1: Distributed Mass boudnary condition panel. Select the mass definition, define the mass value and assign to the corresponding faces.
  • Total Mass: Specify the total mass (in kg) to be distributed proportionally across the selected surface based on element area or length
  • Area Density Mass: Specify mass per unit area (in kg/m²) for direct surface mass assignment

It is important to mention that, for this boundary condition to work properly, gravity needs to be defined in the correct direction.

Definition of gravity for distributed mass boundary condition.
Figure 2: Definition of gravity for Distributed Mass boundary condition.

Supported Analysis Types

The following analysis types support the usage of this boundary condition:

Example

Taking into consideration the beam presented in Figure 2 with a total distributed mass of 1000 kg, the following displacement (deflection) is obtained in the x-direction:

Deflection in x-direction due to total distributed mass boundary condition.
Figure 3: Deflection in x-direction due to total distributed mass boundary condition.

Last updated: February 12th, 2026

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