MASSPR ( entity, nopts, iopts, accrcy, periph, amount, mass, cofg, inert,
==========================================================================
ifail )
=======
Mass and related property calculation
Receives:
KI_tag_list_entity *entity --- entity or list of entities
<KI_int_nitems> *nopts --- number of options in 'iopts'
KI_cod_maop iopts[ nopts ] --- mass property request options
double *accrcy --- accuracy parameter, 0.0 - 1.0
Returns:
KI_tag_list_dbl *periph --- size of periphery of entity
KI_tag_list_dbl *amount --- size of entity
KI_tag_list_dbl *mass --- mass
KI_tag_list_dbl *cofg --- centre of gravity
KI_tag_list_dbl *inert --- inertia tensor at cofg
KI_cod_error *ifail --- failure indicator
Specific errors:
KI_different_types Bodies must all be either wire, sheet or solid
Entities in list not all of the same type
KI_mass_eq_0 Bodies have zero total mass
KI_density_le_0 A body has zero or negative density
KI_missing_geom A topological entity lacks geometry
KI_request_not_supported Unimplemented mass property requested
KI_empty_assy No bodies referenced by list of assemblies
KI_general_body general body
KI_wrong_entity_in_list Entity of wrong type in list
KI_contradictory_request Contradictory or unknown request made
KI_bad_accuracy Accuracy out of range
Description:
This routine calculates the following geometric properties of certain
topological entities:
Type "Periphery" "Amount" "Mass" "Cofg, inertia"
========================================================================
Edge - Length - Cofg, Inertia
Face Circumference Area - Cofg, Inertia
Wire body - Length Mass Cofg, Inertia
Sheet Body Circumference Surface Area Mass Cofg, Inertia
Solid Body Surface area Volume Mass Cofg, Inertia
Face/sheet)
considered) Surface area Volume - Cofg, Inertia
as Solid )
Assembly Total periphery Total amount Mass As for components
No other types are acceptable. If a list of entities is given they must all
be of the same type, and the results are totals, except for the centre of
gravity and inertia, which refer to the collection of entities. For an
assembly or list of assemblies, the results take account of all body
occurrences in the assemblies or sub-assemblies; these occurrences must all be
the same body type.
Results given as '-' are returned as NULTAG.
The mass is the product of the amount and the density; any bodies with no
density attribute will be regarded as having density 1.0. Areas are always
treated as unsigned. The amount, mass, centre of gravity, and inertia of
bodies and assemblies will take account of any void shells.
For bodies or assemblies, 'inert' is the inertia tensor at the centre of
gravity ( with respect to the X, Y, Z axis directions ).
Information found:
There are four possible requests which control how mass properties are
calculated - these are given in a list of integers, with the number in the
list supplied as another argument. The requests control the level of mass
properties calculated, whether periphery data is given, what style the
errors are presented in and whether the received entities are considered
separately or as part of a single entity.
The main mass properties form a hierarchy in that the mass is needed to find
the centre of gravity, and the centre of gravity is needed to find the
inertia. One request code controls the level to which calculations are
done. If no request for this option is given, the default is MAOPIN.
Request code Interpretation
========================================================
MAOPNA No data in this hierarchy to be is found
MAOPAM Finds the amount and mass of the entities only
MAOPCG Finds the centre of gravity as well
MAOPIN Finds the moment of inertia as well
The periphery data is controlled separately by another request, which needs
only two settings. The default is MAOPPE.
Request code Interpretation
========================================================
MAOPNP No periphery data calculated
MAOPPE Calculates the periphery of the entities
Accuracy of calculation:
If the calculation requested only involves simple geometries, an accurate
method of integration is used, and the parameter 'accrcy' is ignored. In
complex cases 'accrcy' is used to determine the accuracy of the calculation:
it must be in the range 0.0 to 1.0, and as it approaches 1.0, the
calculation will be more accurate but slower. The dependence of errors on
'accrcy' is not linear, and values below 0.9 will give only coarse
approximations. A great deal of calculation may be required to satisfy an
'accrcy' of 1.0, and in general convergence cannot be guaranteed. Supplying
an accuracy parameter of 1.0 for parts involving B-surfaces is not
recommended.
Error estimates:
Mass properties can be requested to calculate error estimates for the values
found. For each returned list, the initial entries give the calculated
value, and subsequent entries give the associated errors. There is the
option of having no errors output, of having a single quantity to add or
subtract from the answer value, or having intervals specifying the ranges of
the errors. For the centre of gravity, the latter two would correspond to a
sphere centred on the answer vector and a box containing it. The default is
to have MAOPNE.
Request code Interpretation
========================================================
MAOPNE No errors are given
MAOPEM Modulus +/- to give error range
MAOPEI An interval bracketing the value is given
This table gives the number of doubles returned for each mass property,
first for the value and then for the error option.
Value No Error Error modulus Error interval
======================================================================
Periphery 1 0 1 2
Amount 1 0 1 2
Mass 1 0 1 2
Centre of Gravity 3 0 1 6
Moment of Inertia 9 0 1 18
The moment of inertia returned using the 'MAOPEM' option consists of 9
doubles representing the inertia and 1 double giving the error modulus.
Using the 'MAOPEI' option, the data returned consists of 9 doubles
representing the inertia followed by 9 doubles for the lower limits and
then 9 doubles giving the upper limits of inertia.
Considering received entities as a single entity:
It is possible to supply a list of faces or a list of sheet bodies
and have them considered as forming the boundary of a single solid.
Request code Interpretation
=====================================================================
MAOPCS supplied list of faces/sheets will be
considered as the boundary of a single solid
Under this option the mass will not be returned, as there is currently
no way of unambiguously specifiying a density for the calculation.
The Moment of Inertia will be returned, but will be calculated without
reference to any density attributes attached to the supplied entities,
effectively assuming a density of one for the solid of which they form the
boundary.
No checking is done that the faces or sheets provided do form a valid
solid boundary. If they do not, the the returned results are likely to
be meaningless.
Entities are faces or edges:
A list of faces without the MAOPCS option or a list of edges will be
treated as a sheet or wire body respectively. Again the density is not
specified, so the Moment of Inertia will be calculated with an assumed
density of one.
This function does not support general bodies or assemblies which
contain a general body.
