Development of a finite element-based computer program to determine the CG and area/mass moments of inertia of solids of complicated geometries

Abstract

This FYP (Final Year Project) deals with the development of a finite element-based computer program to determine the center of gravity (CG) and area/mass moments of inertia of solids of complicated geometries. The calculation of these properties is important in the design and analysis of engineering structure and components.

There are analytical formulas to calculate these properties for simple geometries such as sphere, cylinder, and cubes. The geometry of components encompassing in real life design is quite complicated. One can break down the complex geometry to simpler shapes and apply the analytical formulas. Often this could be very cumbersome, time consuming and result is often not accurate. Numerical Method is another approach that one can used. In this project, finite element method is used to determine the geometric properties. A computer program is developed to determine these properties.

The code for calculating the geometric properties is being developed in MATLAB. The logic of the program uses both shape functions and numerical integration to achieve its result. This allows to calculate the summation of all the desired geometric properties of the finite element. The input data for the geometrical shape (which is used as the input to the MATLAB code) is generated in ANSYS. The geometrical model for the test generation is either created in ANSYS or created in SOLIDWORKS and imported into ANSYS.

The input data is then cleaned by using Excel VBA before inputting into MATLAB. To verify the MATLAB code that was developed, a few applications have been considered. These includes sphere, cylinder, gears, and crankshaft. The results have been compared with the geometrical problems given by ‘VSUM’ command of ANSYS. The program is seen to give accurate values.

Therefore, the main objective of this research is to develop a program in MATLAB. It will be able to compute geometric properties of a 3-D object that is imported by ANSYS. A learning objective was done by developing a program for the use of 2-D applications.