Tecnologia

FEMM 4.2 Electrostatics Tutorial1 David Meeker [e-mail] January 25, 2006 1. Introduction Finite Element Method Magnetics (FEMM) is a finite element package for solving 2D planar and axisymmetric problems in electrostatics and in low frequency magnetics. The program runs under runs under Windows 95, 98, ME, NT, 2000 and XP. The program can be obtained via the FEMM home page at http://femm.foster-miller.com. The package is composed of an interactive shell encompassing graphical pre- and postprocessing; a mesh generator; and various solvers. A powerful scripting language, Lua 4.0, is integrated with the program. Lua allows users to create batch runs, describe geometries parametrically, perform optimizations, etc. Lua is also integrated into every edit box in the program so that formulas can be entered in lieu of numerical values, if desired. (Detailed information on Lua is available from http://www.lua.org.) There is no hard limit on problem size—maximum problem size is limited by the amount of available memory. Users commonly perform simulations with as many as a million elements. The objective of this document is to get new users “up and running” with the program via a set of step-by-step example electrostatics problems. 2. Basic Introduction: Capacitor with a Square Cross-Section This will take you through a step by step process of analyzing a capacitor with a square crosssection. Users should first refer to the FEMM user’s manual regarding the general interface (i.e. keyboard and mouse controls). This example, as shown below in Figure 1, the outer square has a 4 cm size and the inner square has a 2 cm size. The geometry extends for 100 cm in the “into-the-page” direction. The dielectric between the plates is air. We seek to build the problem, analyze it, and determine the capacitance.

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This document is based on the "Introduction to FEA with FEMM" tutorial by Ian Stokes-Rees, TSS (UK) Ltd.

Many thanks to Kostadin Brandisky of the Technical