VM8

VM8
Parametric Calculation of Point-to-Point Distances

Overview

Reference:	Any Basic Geometry Text
Analysis Type(s):	Parametric Arithmetic
Element Type(s):	None
Input Listing:	vm8.dat

Test Case

Write a user file macro to calculate the distance d between either nodes or keypoints in PREP7. Define abbreviations for calling the macro and verify the parametric expressions by using the macro to calculate the distance between nodes N₁ and N₂ and between keypoints K₃ and K₄.

Figure 11: Parametric Calculation Problem Sketch

Geometric Properties

N₁ (x, y, z) = 1.5,2.5,3.5

N₂ (x, y, z) = -3.7,4.6,-3

K₃ (x, y, z) = 100,0,30

K₄ (x, y, z) = -200,25,80

Analysis Assumptions and Modeling Notes

The user file is created by the *CREATE command within the run. In normal use, this file would most likely already exist locally. Colons are used in the user file to create non-echoing comments (the colon character specifies a branching label in Mechanical APDL). The active coordinate system is saved and restored within the macro to ensure Cartesian coordinates in the distance calculations and to re-establish the active coordinate system after the macro is used. Lowercase input is used throughout. Input case is preserved by Mechanical APDL where appropriate (system-dependent).

Results Comparison

	Target	Mechanical APDL	Ratio
N₁ - N₂ distance (LEN2)	8.5849	8.58	1.000
K₃ - K₄ distance (LEN1)	305.16	305.16	1.000