Nodal Masses

 

 

 

Enter lumped mass data (Lumped Translation Mass/Rotational Mass Moment of Inertia) for nodes, or modify or delete previously entered nodal masses.

 

 

 

From the Main Menu select Model > Masses > Nodal Masses.

 

Select Geometry > Masses > Nodal Masses in the Menu tab of the Tree Menu.

 

 

 

Click  to the right of Nodal Masses: Display the Nodal Mass Table

Options

 

Add: Enter or add new nodal lumped mass data for selected nodes

 

Replace: Replace previously entered nodal lumped mass data for selected nodes

 

Delete: Delete previously entered nodal lumped mass data for selected nodes

 

Nodal Mass

 

Enter lumped mass data with respect to GCS.

 

mX: Translational Lumped Mass in GCS X-direction

 

mY: Translational Lumped Mass in GCS Y-direction

 

mZ: Translational Lumped Mass in GCS Z-direction

 

rmX: Rotational Mass Moment of Inertia about GCS X-axis

 

rmY: Rotational Mass Moment of Inertia about in GCS Y-axis

 

rmZ: Rotational Mass Moment of Inertia about in GCS Z-axis

 

 

Note
Each mass component is calculated as below.

 

- Lumped mass component =

 

- Rotational Mass Moment of Inertia =

 

Where, r is a distance from the center of mass to the center of a relevant mass component

 

The unit of a lumped mass [weight * (time2/length)] is the weight divided by the acceleration of gravity and the unit of a rotational mass moment of inertia [weight * (time2/length)] * length2] is the mass multiplied by the square of the length.

 

In the MKS or English unit system, the mass data must be entered as the weight divided by the acceleration of gravity. The acceleration of gravity is defined by Model > Structure Type. For reference, in the SI unit system, the unit for mass is [kg] or [ton]. The values of weights used in the MKS unit system must be multiplied by the acceleration of gravity to enter the modulus of elasticity or the loads in the SI unit system.

 

 

Method of calculating Mass data