Mass Properties

The Mass Properties for Volume, Surface, Weight and Centre of Gravity can be queried from any element in the system that has graphical representation or owns elements that have graphical representation.

These Mass Properties are calculated in a variety of ways, depending on the type of element. These are namely:

• User Input - Usually for Weight and CofG of elements such as equipment, vessels, etc.

• Catalogue Data - Usually for Weight of components such as Pipe fittings, tables, chairs

• 3D Model Calculation by the System - Weight can be calculated for such as Beams, Columns, Panels where the Volume is used in combination with the material density. Volume and Surface area are always calculated by the System.

• Hull elements in Marine - These are analytically computer by the System (i.e. not from faceted model, but exact geometry).

User Input

Elements that own primitives, such as Equipment and Sub-Structure for example have the following attributes for user input:

The above attributes can be queried using a USC--- attribute such as USCWEIGHT to expand any expression for normal weight.

for example, USRWEIGHT (RPRO WEIG)

Q USCWEIGHT gives actual result, say 1000

Similar applies for all above attributes.

Catalogue Data

Elements that have a Specification Reference (SPREF) will also have a Component Reference (CMPREF). The Component Weight can be set here. The setting will usually be numeric such as 10 for the weight of a pipe valve. However the component can also be an expression such as (RPRO TWEI) which allows for more user control. Component wet weights can also be set in this way.

For Centre of Gravity (Dry and Wet) it is possible to create a Ppoint with a Purpose attribute of COFG (or WCOG) that will be used as the Centre of Gravity position. Otherwise P0 is considered to be the CofG.

3D Model Calculation by the System

For Volume and Surface calculations the results are calculated by the system, using the Representation Mass level. As per drawing representation levels an element can be displayed as a very simple or complex model using different representation levels, then the same principle applies for Mass Properties. Obviously it is quicker for the system to calculate a more basic representation.

Hull Elements in Marine

Hull items expose HWEIG, HVOLU HSRFA and HCOFG attributes and these are used for all the N/G/R variants of SRF, WEI, VOL and COF (e.g. NSRF, GSRF, RSRF) outfitting pseudo attributes. There is no distinction between gross, net and rough variants as all most accurate is fast to compute.

Mass Properties for Hull provide the full hierarchical structure values, (i.e. NOT ONLY) and so are consistent with the N/G/R attributes now supported.

For the inside/outside qualifiers; as there is potential that only part of the element will be used, then, in this situation the facetted model (GML) is used.