Surface

Model Element

Class Name

Surface

Description

Surface defines a parametric surface element in 3D space. A parametric surface is defined in terms of two free parameters: u and v. This means that the 3 coordinates (x,y,z) of any point P on the surface is a function of the two free parameters u and v. Surface is available in 3 flavors.

Attribute Summary

Name	Property	Modifiable by command?
id	Int ()
label	Str ()	✓
uclosed	Bool (False)	✓
vclosed	Bool (False)	✓
minpar	Double ([-1, -1], count=2)	✓
maxpar	Double ([ 1, 1], count=2)	✓
function	Function ("SURSUB")
routine	Routine ()

Usage

#1: Defined in a compiled user-written subroutine

Surface (function=userString, routine=string, optional_attributes)

#2: Defined in a Python script

Surface (function=userString, routine=functionPointer, optional_attributes)

Attribute Description

Defined in a compiled user-written subroutine

function

String

The list of parameters that are passed from the data file to the user-defined subroutine.

The function attribute is mandatory

routine

String

Specifies an alternative name for the user subroutine. The name consists of two pieces of information, separated by “∷”. The first is the pathname to the shared library containing the function that computes the response of the user-defined Surface. The second is the name of the function in the shared library that does the computation.

An example is: routine=”/staff/Altair/engine.dll∷mySurface”

•	”/staff/Altair/ engine.dll is the dll

•	“mySurface” is the function within this DLL that performs the calculations

The attribute routine is optional. When not specified, routine defaults to SURSUB.

Defined in a Python function

function

String

The list of parameters that are passed from the data file to the user defined Python function.

The function attribute is mandatory

routine

Pointer to a callable function in Python

An example is: routine=mySurface”

•	mySurface is a Python function or method that can be called from wherever the model resides.

The attribute routine is optional. When not specified, routine defaults to SURSUB.

Optional Attributes – Available to all description methods

Integer

Specifies the element identification number. This number must be unique among all the Surface objects in the model.

This attribute is optional. MotionSolve will automatically create an ID when one is not specified.

Range of values: id > 0

label

String

Specifies the name of the Surface object.

This attribute is optional. When not specified, MotionSolve will create a label for you.

uclosed

Boolean

If the surface is closed in the u parametric space, select True.
If the surface is open in the u parametric space, select False.

The uclosed attribute is optional. When not specified, it defaults to False.

vclosed

Boolean

If the surface is closed in the v parametric space, select True.
If the surface is open in the v parametric space, select False.

The vclosed attribute is optional. When not specified, it defaults to False

minpar

List of 2 Doubles

Specifies the list of minimum value of u and v.

The minpar attribute is optional. When not specified, it defaults to [-1,-1]

Note, when specified, minpar < maxpar.

maxpar

List of 2 Doubles

Specifies the list of maximum value of u and v.

The maxpar attribute is optional. When not specified, it defaults to [+1,+1]

Note, when specified, minpar < maxpar.

Comments

1.	See Properties, for an explanation about what properties are, why they are used and how you can extend these.

2.	For a more detailed explanation about Surface, see the Comments in the XML syntax section

Example

1.	Define a cylindrical surface in a user-subroutine.

#Define the surface in the function cylindricalSurface ()

from math import sin, cos, pi

def cylindricalSurface (id, par, npar, u, v, iord, iflag):

values = []

r = par [0]

if iord == 0:

values.append (r * cos (u)) # x

values.append (r * sin (u)) # y

values.append (v) # z

elif iord == 1:

values.append (-r * sin (u)) # dx / du

values.append ( r * cos (u)) # dy / du

values.append (0.0) # dz / du

values.append (0.0) # dx / dv

values.append (0.0) # dy / dv

values.append (1.0) # dz / dv

elif iord == 2:

values.append (-r * cos (u)) # d2x / du du

values.append (-r * sin (u)) # d2y / du du

values.append (0.0) # d2z / du du

values.append (0.0) # d2x / du dv

values.append (0.0) # d2y / du dv

values.append (0.0) # d2z / du dv

values.append (0.0) # d2x / dv dv

values.append (0.0) # d2y / dv dv

values.append (0.0) # d2z / dv dv

elif iord == 3:

values.append ( r * sin (u)) # d3x / du du du

values.append (-r * cos (u)) # d3y / du du du

values.append (0.0) # d3z / du du du

values.append (0.0) # d3x / du du dv

values.append (0.0) # d3y / du du dv

values.append (0.0) # d3z / du du dv

values.append (0.0) # d3x / du dv dv

values.append (0.0) # d3y / du dv dv

values.append (0.0) # d3z / du dv dv

values.append (0.0) # d3x / dv dv dv

values.append (0.0) # d3y / dv dv dv

values.append (0.0) # d3z / dv dv dv

# Return the computed values

return values

# Define the Surface and refer to the user-subroutine cylindricalSurface ()

mysurface = Surface (function=”user (10)”, routine=cylindricalSurface, uclosed=True,

vclosed=False, minpar=[0, -150], maxpar=[2*pi, 150])