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*Mass

Purpose

To specify a point mass or a point rotary inertia.

Theory

Refer to Point Masses and Point Buoys for further information on this feature.

Keyword Format

Two types of line which can be repeated as often as necessary.

Line defining a point mass:

Node (Number or Label), Mass [, TYPE=MASS]

Line defining a point mass without any gravitational force/weight term:

Node (Number or Label), Mass, TYPE=NO WEIGHT MASS

Line defining a point rotary inertia:

Node (Number or Label), Inertia, TYPE=ROTARY INERTIA

If you specify a node label rather than a node number, it must be enclosed in {} brackets.

Table Input

Notes

(a)Point masses are typically included in both the force vector (as a weight term) and the mass matrix (as an inertia term), but you can omit the former if you wish. This could be useful in Floating Body analysis, where gravitational (and mean buoyancy) forces acting on the floating body are generally not included. It is typically assumed that the initial position of floating body represents the static equilibrium configuration, hence the static gravity and buoyancy forces cancel each other out, and so are not modelled explicitly. Dynamic effects are included obviously. The *FLOATING BODY keyword allows you to model the vessel mass at the centre of gravity of the hull, but you may wish to include other masses at different locations, such as a wind turbine generator.