FELIPE Online Manual

The following table provides links to webpages for various chapters of the User Manual. The full manual can be accessed as a pdf file here.

Contents:

  1.   Introduction
  2.   Using the pre-processor PREFEL
  3.   Solving Poisson's equation: theory and programming
  4.   Linear elasticity: theory and programming
  5.   Beams and frames: theory and programming
  6.   Using the post-processor FELVUE
  7.   The "main engines"
  8.   Global matrix storage, and equation solvers
  9.   The example datafiles
  10.   Further reading
  11.   Frequently asked questions

Introduction

FELIPE (Finite Element Learning Package) is a software package whose primary objective is to help students understand the finite element method in mathematics and engineering, and develop their own f.e. programs. Its advantage over the f.e. textbooks which provide their example programs printed or on ftp or cd-rom, is that it combines full, commented and documented source code (in standard Fortran77) for the f.e. `main engines', with powerful interactive graphics pre- and post-processors capable of generating complex, detailed meshes. Because of this, it is also very suitable for practising engineers and researchers as a low-cost alternative to the many commercial ``black box'' packages on the market (which do not provide source code).

The principal components of FELIPE are:

By this means, users of FELIPE have the interactive graphics processing power of a commercial finite element package, combined with fully-documented source code which they can modify and extend for their own purposes. The package is completely self-standing; the only supporting software needed is a Fortran compiler if the user wishes to modify the source code and re-compile it. Since the pre- and post-processors communicate with the main f.e. programs through formatted ASCII data files, they can also be interfaced with other finite element programs, whether in Fortran or another language.

The pre- and post-processors are compiled under FTN77 (as are the executable versions of the `main engines'), which includes a memory extender; thus, large meshes can thus be created, and problems of real mathematical and engineering significance solved. (The processors are dimensioned to handle a maximum of 900 elements, and 3,000 nodes.) They make extensive use of the graphics and mouse routines available with the FTN77 compiler, and can also produce PostScript graphics files for subsequent processing by, for example, GhostScript software (available from www.hensa.ac.uk by ftp) and printing on LaserJet or DeskJet printers. The `main engines' can also be compiled and run using FTN77 (which is available for personal use free from the Salford software website), but if this is not available any other Fortran compiler can be used, as they are written in standard Fortran77.

The nine `main engines'

The three Basic-level `main engines', and their principal features, are now listed:

  1. POISS.FOR
    Application: solves Poisson's equation -a_x u_{xx} - a_y u_{yy} = f(x,y) on an arbitrary 2D domain.
    Material properties: diffusion coefficients a_x, a_y
    Primary nodal unknown: potentials U
    Secondary unknowns: flow rates U_x, U_y
    Elements used: 3-noded linear triangles.
    Boundary conditions: reflecting, radiating and Dirichlet boundaries
    File size: 25.8KB
    Analysis type: linear
    Matrix storage: symmetric band
    Solution algorithm: Choleski (L.L^T) decomposition

  2. ELAST.FOR
    Application: solves plane strain, plane stress or axisymmetric linear elasticity problems
    Material properties: Young's modulus E, Poisson's ratio \nu, thickness t, tensile strength \sigma_{\mbox{ten}}
    Primary nodal unknown: displacements u,v
    Secondary unknowns: stresses \sigma_x, \sigma_y, \tau_{xy}
    Elements used: 8-noded `serendipity' quadrilaterals
    Boundary conditions: fixities in x or y planes
    Loading: point loads, surface tractions
    File size: 34.8KB
    Analysis type: linear
    Matrix storage: symmetric band
    Solution algorithm: Choleski (L.L^T) decomposition

  3. FRAME.FOR
    Application: analyses plane frames comprising elastic beams.
    Material properties: Young's modulus E, Moment of Inertia I, cross-sectional area A
    Primary nodal unknown: displacements x,y and rotations \theta
    Elements used: 2-noded cubic beam elements.
    Boundary conditions: displacement and rotation fixities
    Loading: point loads, surface tractions
    File size: 24.4KB
    Analysis type: linear
    Matrix storage: element-by-element matrices on scratch file
    Solution algorithm: preconditioned conjugate gradients, with diagonal preconditioning

The six Advanced-level `main engines' are:

  1. ELADV.FOR
    Application: Large-scale 2D elasticity analyses
    Material properties: Young's modulus E, Poisson's ratio \nu, thickness t, tensile strength \sigma_{\mbox{ten}}
    Primary nodal unknown: displacements u,v
    Secondary unknowns: stresses \sigma_x, \sigma_y, \tau_{xy}
    Elements used: 3- and 6-noded triangles, 4- and 8-noded quadrilaterals, mapped infinite elements, 2- and 3- noded (cubic and quartic) beam elements
    Boundary conditions: fixities in x or y planes
    Loading: point loads, specified displacements, surface tractions, body forces, excavation loading
    File size: 91.9KB
    Analysis type: linear
    Solution algorithm: symmetric frontal algorithm

  2. PLAST.FOR
    Application: plane strain associated-flow Mohr-Coulomb elasto-plasticity analyses
    Material properties: Young's modulus E, Poisson's ratio \nu, triaxial stress factor k, strength \sigma_c
    Primary nodal unknown: displacements u,v
    Secondary unknowns: stresses \sigma_x, \sigma_y, \tau_{xy}
    Elements used: 8-noded `serendipity' quadrilaterals
    Boundary conditions: fixities in x or y planes
    Loading: point loads, surface tractions
    File size: 50.3KB
    Analysis type: nonlinear, iterative, incremental
    Matrix storage: symmetric band
    Solution algorithm: Choleski (L.L^T) decomposition

  3. VPLAS.FOR
    Application: plane strain Mohr-Coulomb elasto-viscoplasticity analyses, with non-associated flow
    Material properties: Young's modulus E, Poisson's ratio \nu, triaxial stress factor k, strength \sigma_c, fluidity \gamma, dilation factor l
    Primary nodal unknown: displacements u,v
    Secondary unknowns: stresses \sigma_x, \sigma_y, \tau_{xy}
    Elements used: 8-noded `serendipity' quadrilaterals
    Boundary conditions: fixities in x or y planes
    Loading: point loads, surface tractions
    File size: 75.5KB
    Analysis type: nonlinear, incremental, time-dependent
    Solution algorithm: Frontal algorithm, for non-symmetric matrices

  4. PLADV.FOR
    Application: as PLAST, but with a range of solution algorithms
    Material properties: Young's modulus E, Poisson's ratio \nu, triaxial stress factor k, strength \sigma_c
    Primary nodal unknown: displacements u,v
    Secondary unknowns: stresses \sigma_x, \sigma_y, \tau_{xy}
    Elements used: 8-noded `serendipity' quadrilaterals
    Boundary conditions: fixities in x or y planes
    Loading: point loads, surface tractions
    File size: 67.7KB
    Analysis type: nonlinear, iterative, incremental
    Matrix storage: symmetric skyline, element-by-element
    Solution algorithms: Choleski (L.L^T) and L.D.L^T decomposition, conjugate gradients with diagonal or Incomplete Choleski preconditioning

  5. THERM.FOR
    Application: plane stress/strain thermoelasticity
    Material properties: Young's modulus E, Poisson's ratio \nu, thickness t, conductivity coefficient k, coefficient of thermal expansion \alpha
    Primary nodal unknown: displacements u,v, temperatures T
    Secondary unknowns: stresses \sigma_x, \sigma_y, \tau_{xy}
    Elements used: 4-noded (linear) and 8-noded (serendipity) quadrilaterals with (u,v,T) degrees of freedom at all nodes
    Boundary conditions: fixities in x or y planes, reflecting and Dirichlet temperature boundaries
    Loading: point loads, surface tractions
    File size: 44.2KB
    Analysis type: linear, coupled
    Matrix storage: nonsymmetric band
    Solution algorithm: Gauss elimination for non-symmetric matrices

  6. CONSL.FOR
    Application: plane strain soil consolidation (poroelasticity)
    Material properties: Young's modulus E, Poisson's ratio \nu, effective permeabilities \frac{k_x}{\gamma_w}, \frac{k_y}{\gamma_w}, effective porosity \frac{\eta}{K_f}
    Primary nodal unknown: displacements u,v, pore-pressures p
    Secondary unknowns: effective stresses \sigma_x, \sigma_y, \tau_{xy}
    Elements used: 8-noded `serendipity' quadrilaterals with pore-pressure d.o.f.s at corner nodes only
    Boundary conditions: fixities in x or y planes, impermeable or permeable boundaries
    Loading: point loads, surface tractions
    File size: 53.4KB
    Analysis type: linear, coupled, time-dependent
    Matrix storage: symmetric band
    Solution algorithm: L.D.L^T decomposition

Installation

To install the package from the floppy disk, run the self-extracting zip file FELIPE.EXE which is on the disk. You can do this by locating the file on your disk drive (normally the A: drive) using My Computer or Windows Explorer, and double-clicking on it. Alternatively, type a:\felipe.exe into the command line copy using the Run... utility from the Start menu. You will be prompted to nominate a directory into which the FELIPE files should be unzipped; the default is C:\FELIPE.

If you have already downloaded the evaluation version of FELIPE from the website into the C:\FELIPE directory, you can still use the same directory; the demonstration versions of the files will be overwritten by the full versions, and new files added.

The installation process does not alter any Windows settings on your PC. To uninstall FELIPE, simply delete the directory containing the files.

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In this manual, Chapter 2 describes how to use the PREFEL pre-processor.

The next three chapters describe the three Basic-level `main engines': Chapter 3 covers the theory and programming of the Poisson solver, while Chapter 4 describes the solver for elasticity problems, and Chapter 5 deals with beam theory.

Chapter 6 describes the use of the FELVUE post-processor. Then

Chapter 7 summarizes the operation and use of the other six, Advanced-level `main engines'. Chapter 8 covers the various algorithms used for equation solution.

Chapter 9 documents the sample datafiles provided in the FELIPE package.

The final Chapter suggests ways in which the `main engines' may be modified, and new `main engines' written, and gives recommendations for textbooks for further reading about the finite element method.

Acknowledgements: I am very grateful to Prof. J.R. Whiteman and Dr. M.K. Warby for permission to use in FELIPE some of the basic graphics and PostScript subroutines developed by Dr. Warby, and to Dr. T.-Y. Chao for working with me on the programming and documentation of the elasticity module. I also acknowledge the support of the Enterprise in Higher Education Unit at Brunel University, in enabling me to work on this project. The Fortran coding of the elasticity 'main engines' is based on the FINEPACK program developed at the Dept. of Civil Engineering, University College Swansea, and I am grateful to Dr. D.J. Naylor for permission to use this.

 
 
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