GeomSect_001 Case4 Vertical plane non-parallel to XYZ coordinate system planes

Contents

The data file for this exercise is located in GeomSect_001/Exercices/Case4/Data. Look for ! TODO text in the datafile and follow the instructions.

In this example the section plane is rotated to perform a vertical section in a plane non-parallel to any of the ZX nor YZ planes. This is performed by defining a Coordinate_system defining the rotation.

In the International Society of Biomechanics web page an Excel Spreadsheet developed by Neil Crawford to calculate direction cosines for a X, Y, Z sequential 3D rotation can be downloaded. The instructions are included in the spreadsheet. Note that rotation should be performed using the tilt-twist input in the spreadsheet following the sequence:

1Define the sequential rotation in the input cells (B3 to B5)

2Look at the tilt-twist values provided in cells M3 to M5

3Change the input of the B3 to B5 for the tilt-twist values

4Copy the resulting direction cosines matrix in cells Q20 to S22

Data File

* Coordinate_system NUM=1

! ---------------------------------

Direction_cosines IDM=3 JDM=3

0.9397 0.3420 0.0000

0.0000 0.0000 1.0000

0.3420 -0.9397 0.0000

* Geometry_section_surface

! ---------------------------------

Section_type "XY_local"

Generation_type "Section"

Reference_location IDM=3

4250.0 1000.0 2000.0

Coordinate_system 1

Output_level 3

Groups IDM=4

"formation0"

"formation1"

"formation2"

"formation3"

1A coordinate system to describe the rotation for sectioning is defined. In the present case the direction cosines correspond to a sequential rotation of:

a.-90º along X axis

b.0º along Y axis

c.20º along Z axis

d.Note that the final input in cells (B3, B4, B5) for the til-twist method has been (-90, -20, 0).

2Section_type is set to "XY_local" (flat and initially parallel to XY plane).

3Generation_type is set to "Section" (a .geo file containing the sectioned geometry and a datafile will be generated).

4Reference location is defined to be at the center of the geometry.

5Coordinate system 1 is assigned to the sectioning in order to rotate the section.

Results

The result files for the project are in directory: GeomSect_001\Case4\Results. Note that the output section 2D geometry is oriented within plane XY as 2D problems in ParaGeo must be oriented in that plane.

GeomSect_001_Case4_results

3D geometry showing the section plane (left). Sectioned geometry (right)