This sheet allows the definition of any geometry by means of a drawing translated into a dxf file.
You don't need any knowledge on how a dxf file is structured to use this application. However some more information are reported below for those that are expert with dxf files.
The warping dependent section properties (mainly those that are used for a torsion analysis), are calculated by means of the application sectionproperties by Robbie van Leeuwen. The torsion modulus is obtained from the maximum calculated torsional shear stress in the section. This value could be lower than what is generally accepted in engineering calculations, as it accounts for stresses in inner corners, that may be high, but normally relevant only for fatigue analysis.
The external contour of the section should not contain reentrant sharp corners, as the torsion and shear analyses might give unreliable results.
You don't need any knowledge on how a dxf file is structured to use this application. However some more information are reported below for those that are expert with dxf files.
The warping dependent section properties (mainly those that are used for a torsion analysis), are calculated by means of the application sectionproperties by Robbie van Leeuwen. The torsion modulus is obtained from the maximum calculated torsional shear stress in the section. This value could be lower than what is generally accepted in engineering calculations, as it accounts for stresses in inner corners, that may be high, but normally relevant only for fatigue analysis.
The external contour of the section should not contain reentrant sharp corners, as the torsion and shear analyses might give unreliable results.
Section defined in a dxf: instructions
Just prepare the drawing representing the section with your favourite CAD application, using lines, arcs, circles and polylines.
The section is represented by means of its outer contour and possibly of one or more internal contours representing holes (IMPORTANT NOTE: no holes allowed at present!). All contours must be closed, or the application will fail.
The dimensions are not important, the height (depth) and the scale of the section may be defined in the xcalcs sheet.
Then generate a dxf file from the drawing and save it to a suitable location.
Now go to xcalcs, load the sheet, click on the blue image on the right and enter the name of your dxf file.
When the sheet is reloaded, define, if necessary, the height (depth) of the section and look at the result.
The section is represented by means of its outer contour and possibly of one or more internal contours representing holes (IMPORTANT NOTE: no holes allowed at present!). All contours must be closed, or the application will fail.
The dimensions are not important, the height (depth) and the scale of the section may be defined in the xcalcs sheet.
Then generate a dxf file from the drawing and save it to a suitable location.
Now go to xcalcs, load the sheet, click on the blue image on the right and enter the name of your dxf file.
When the sheet is reloaded, define, if necessary, the height (depth) of the section and look at the result.
Section defined in a dxf: more information
The purpose of this calculation sheet is to calculate the torsional properties of a section defined by a dxf file. More information
upon calculation methods may be obtained upon request: in this event please always specify the reason for the request
(perhaps an unexpected result).
The results are obtained by solving in finite differences the differential equation for torsional stresses.
The following rules are used in interpreting the file:
- the dxf file may be a complete file, or also might contain only the ENTITIES SECTION
- only the ENTITIES SECTION is processed
- as a consequence, frozen layers, line types, units of measurement and many other features are discarded
- the z coordinate is not considered, only the x and y coordinates are processed
- angles are assumed to be expressed in sexagesimal degrees
- only and all the following entities are processed: LINE CIRCLE ARC LWPOLYLINE POLYLINE
- make sure there are no superimposed entities, as the application does not detect this condition and the results will be unpredictable
The results are obtained by solving in finite differences the differential equation for torsional stresses.
The following rules are used in interpreting the file:
- the dxf file may be a complete file, or also might contain only the ENTITIES SECTION
- only the ENTITIES SECTION is processed
- as a consequence, frozen layers, line types, units of measurement and many other features are discarded
- the z coordinate is not considered, only the x and y coordinates are processed
- angles are assumed to be expressed in sexagesimal degrees
- only and all the following entities are processed: LINE CIRCLE ARC LWPOLYLINE POLYLINE
- make sure there are no superimposed entities, as the application does not detect this condition and the results will be unpredictable