Apply Mass

Nodes

Connector entities are created at the locations defined by selected FE nodes.

Points

Connector entities are created at the locations defined by selected geometry points.

Connectors

Mass is applied to existing connector entities, so you can update applied masses by updating the connector.

Nodes

Mass is applied via nodes. When this option is chosen, nsm becomes unavailable in the mass type field.

Elements

Mass is applied to the nodes of elements.

Components

Mass is applied to the nodes of entire components.

Tags

Mass is applied to nodes via their tags.

Assemblies

Select the assemblies to be added as link entities.

Proximity

Connect entities to any entities of the location type within the search tolerance.

User Select

Manually select entities.

nsm

The mass is a non-structural mass and defines/updates the required solver cards.

Note: Only available for OptiStruct and Nastran solver interface.

A group entity is created for each connector when realizing this connector type. The group gets a NSM1 or a NSML1 card assigned.

The group references all in the connector-linked elements. These linked elements include elements from direct element links, but also the elements belonging to a component or assembly link. The NSM entity type attribute decides whether the reference is realized via a simple element list, or the reference is realized via a property list (of a certain type). The property reference requires clear properties, which exactly condense the elements linked in the connector.

Point Mass

Mass is a single mass element created at a node.

Rigid Mass

Mass takes the form of a mass element connected to nodes with rigid elements (multiple RBE2).

RigidLink Mass

Mass takes the form of a mass element connected to nodes with a rigidlink element (single RBE2).

RBE3 Mass

Mass takes the form of a mass element connected to nodes with a RBE3 element.

This attribute will be written into the connector and is considered during the next realization.

Upon creation of nsm connectors, the FE data (nsm group entity) is realized and a new component (CE_Mass_inc_<include name>) is created inside the current include. The newly created connectors will reside in this new component. Each include is meant to host its own CE_Mass_inc_<include name> component, and a warning will display if the component name already exists in a different include. This helps ensure that unrealizing and rerealizing nsm connectors will keep the FE data in its original include.

The realization routine always looks for the content (elements) of the links and investigates whether they exclusively reference the same properties (direct or indirect) and can be condensed clearly in property references in the NSM group.

Apply To All Nodes

The mass is applied repeatedly, once to each node (so the total mass applied is the mass times the number of nodes).

Divide Mass By Nodes

The mass is divided by the number of nodes, and the result applied to each node.

Divide Mass By Area

Divide the mass= value among the affected nodes.

Note: Only available when the connect what option is not set to nodes.

This method ensures that non-uniform meshes still produce uniform mass distribution.

1. Determining the mass per unit of area (in this example, 10g/10,000mm=0.001g/sq. mm).
2. Determining the area of each element (in this case, all of the 4 elements are 50x50=2500 sq. mm).
3. Multiplying the per-unit mass by the number of units per elem to find each element's total mass. (.001x2500=2.5g per elem in this example).
4. Dividing the elem's mass by the elem's number of nodes (yielding 2.5/4=0.625 per node in this example).
5. Nodes belonging to more than one element receive a per-node mass from each element accumulatively.

Unit Area Distribution

Apply the full mass= value to each square unit of the selected area, then distribute this mass across the area as for divide mass by area (steps 2+). In other words, this follows the same steps as described for divide mass by area with the omission of step 1, so that the full mass= value is used as the per-unit mass. This method produces an area-based distribution but with much higher masses.

Note: Only available when the connect what option is not set to nodes.

$$\frac{\left(10g/m{m}^2\right)\times \left(2500m{m}^2/elem\right)}{4nodes/elem}=6250g/node$$