## Function

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

## Call

From the main menu, select **[Load] tab > [Type : Static Loads] > [Masses] group > [Masses] > [Nodal Masses]**

## Input

### The right "..." of Nodal Masses

Display Nodal Masses 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 GCS Y-axis

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

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 * (time^2/length)] is the weight divided by the acceleration of gravity and the unit of a rotational mass moment of inertia [weight * (time^2/length)] * length^2] 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