28.5 The volume fraction tool

The volume fraction tool creates a scalar discrete field by performing a Boolean comparison between an Eulerian part instance and a second part instance (the reference part instance) that intersects the Eulerian instance. The comparison determines where the two part instances overlap, then assigns each element in the Eulerian instance a volume fraction based on the percentage of the element that is also occupied by the reference instance. The volume fraction is specified as a decimal between zero and one.

The discrete field that is created by the volume fraction tool can be used to assign material instances to the Eulerian part instance (see “Assigning materials to Eulerian part instances,” Section 28.4). The topology of the assigned Eulerian material instance corresponds to the shape of the reference part instance within the Eulerian part instance.

Figure 28–7 and the following procedure summarize the process of using the volume fraction tool:

Figure 28–7 Procedure for using the volume fraction tool.

Using any of the modeling tools and techniques in Abaqus/CAE, create a reference part that corresponds to the geometry of the desired Eulerian material region.
Instance the reference part within the Eulerian part instance. The reference part instance should spatially correspond to the desired Eulerian material region.
Use the volume fraction tool to create a discrete field based on a comparison of the reference part instance and the Eulerian part instance.
Define a material assignment predefined field for the Eulerian part instance using the discrete field created by the volume fraction tool.

An option for the volume fraction tool controls whether the calculated discrete field represents the space inside the reference instance (the volume fraction is nonzero in elements that overlap the reference instance) or the space outside the reference instance (the volume fraction is nonzero in elements that do not overlap or partially overlap the reference instance), as depicted in Figure 28–8.

Figure 28–8 Discrete fields representing volume fractions inside (left) and outside (right) of the shaded reference region.

Typically, calculating the volume fraction outside of a reference instance is used to create an Eulerian material assignment around a Lagrangian part instance in a coupled Eulerian-Lagrangian analysis. Calculating the volume fraction inside of a reference instance is usually used to model complex material assignment fields within a pure Eulerian part instance; in this situation, the reference instance is suppressed after the Eulerian material is assigned. You can also calculate volume fractions inside of a reference instance to create an Eulerian material assignment on the inside of an enclosed Lagrangian shell in a coupled Eulerian-Lagrangian analysis.

To use the volume fraction tool, select ToolsDiscrete FieldVolume Fraction Tool from the main menu bar. For step-by-step instructions for using the tool, refer to “Creating discrete fields for material volume fractions,” Section 63.4.