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Self-made FEM program written on MS Visual Basic

Question asked by Roman Pochinkov in #Coffee Room on Jan 20, 2017
Roman Pochinkov
Roman Pochinkov · Jan 20, 2017
Member of CrazyEngineers
General Information

One of the most important problems, arising during exploitation of various engineering structures of maritime transport, is to estimate the residual strength of structural elements, parts and units, operating in real production conditions. Sea-going vessels are the most numerous and responsible part among all objects of maritime transport. Their hulls belong to the same group of constructions, the strength of which the most difficult to assess due to the extreme complexity of the design. Therefore, the development of numerical methods for the analysis of the stress-deformed condition of the ship hull structures is a highly relevant.

The most promising method for estimation of the stress-deformed condition of ship structures is the finite-element method, which is based on the provisions of structural mechanics and easily implemented on modern digital systems with large memory and high operation speed. Today, there are a lot of commercial software products which realize fundamentals of the method: ANSYS, NASTRAN, ABAQUS, ADINA, etc. However, all these packages are extremely expensive and often represent "black boxes" in which the engineer can not make any changes based on the needs of a specific task. So, the most important thing is the development of independent techniques for the analysis of the stress-deformed condition of the ship hull structures on the basis of the finite element method.

Basics of Operation

Program FASTRAN, which is presented below, is an attempt to create an independent software product for estimation the dynamics of the stress-deformed condition of the ship hull structures by means of the finite element method.

This program consists of a preprocessor, processor and post-processor. The purpose of the preprocessor - to display preliminarily prepared tabular data of the computational model in convenient visual form at current time step (using the methods of 3D graphics). The purpose of the processor - to calculate tabular data of the computational model by means of the finite element method (using high-speed calculation methods for sparse matrices), and receive resulting tables with stresses and strains in each element of the computational model at current time step. The purpose of the postprocessor - to display the results of calculation in convenient visual form at current time step.

Key commands

Consecutive transition from the preprocessor to the processor and then to the postprocessor can be done by pressing "Spacebar".

Step A (preprocessor):
"Arrow Left" - turn camera left;
"Arrow Right" - turn camera right;
"Arrow Up" - turn camera up;
"Arrow Down" - turn camera down;
"Page Up" - bring camera nearer;
"Page Down" - bring camera farer;
"X" - turn camera clockwise;
"Z" - turn camera counterclockwise;
"R" - return camera to initial position;
"N" - turn on/off node labeling mode;
"E" - turn on/off element labeling mode;
"F" - turn on/off element filling mode;
"S" - turn on/off element shading mode;
"I" - turn on/off element information mode;
"End" - view next time step;
"Home" - view previous time step;
"Esc" - deselect element.

"Left Mouse Button" + "Mouse Move" - rotate camera position;
"Right Mouse Button" - select element (element full/brief information).

Step B (processor):
"A" - turn on/off automatic calculation mode;
"End" - calculate next time step.

Step C (postprocessor):
"Arrow Left" - turn camera left;
"Arrow Right" - turn camera right;
"Arrow Up" - turn camera up;
"Arrow Down" - turn camera down;
"Page Up" - bring camera nearer;
"Page Down" - bring camera farer;
"X" - turn camera clockwise;
"Z" - turn camera counterclockwise;
"R" - return camera to initial position;
"N" - turn on/off node labeling mode;
"E" - turn on/off element labeling mode;
"F" - turn on/off element filling mode;
"S" - turn on/off element shading mode;
"I" - turn on/off element information mode;
"End" - view next time step;
"Home" - view previous time step;
"Esc" - deselect element.
"}" - view next result vector (stresses and strains calculated before);
"{" - view previous result vector (stresses and strains calculated before);
"+" - increase construction deformation degree (deformation scale);
"-" - decrease construction deformation degree (deformation scale);
"Tab" - select current extreme value (max stress, min stress, max strain, min strain);
">" - increase current extreme value;
"<" - decrease current extreme value.

"Left Mouse Button" + "Mouse Move" - move camera position;
"Right Mouse Button" - select element (element full/brief information).

Possible Problems

To avoid problems with calculation process change you regional standards ("Start" > "Control panel" > "Language and Regional Standards"). Set the value at the text box "Delimiter of the integer and fractional part of the number" from "," (comma) to "." (dot).

Additional Information

If interrested you can find more information here:
Mechanical Engineering for Everyone
Mechanical Engineering for Everyone: Research Project (FEM) Posted in: #Coffee Room

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