tochnog(1)

NAME

tochnog - simulate mechanics by the finite element method

SYNOPSIS

tochnog [ input-file ]

DESCRIPTION

tochnog is a free finite-element program.

The finite element method is "a general discretization

procedure of continuum problems posed by mathematically defined

statements." [O.C. Zienkiewicz & R.L. Taylor. Finite Element

Method, 5th ed, sect 1.1. 2000.] tochnog implements one-, two

or three-dimensional, or axi-symmetrical computational domains,

each consisting of finite elements connected at nodes; but (un

like as in common finite element programs) with all fields as

sumed to be continuous over the domain. Such continuity gives a

more diffuse but at the same time a more stable numerical scheme,

with the further advantage that all fields are stored not in in

tegration points but in the nodes themselves, leading to a rela

tively easy implementation of remeshing and refining techniques.

Only first order in time equations are solved; time derivatives

are approximated with Euler backward time discretization.

tochnog accepts format-free input; reports results over

points, lines, quadrilaterals, etc., as well as at nodes; outputs

suitably for plotting; provides springs, trusses and 2D beams in

addition to isoparametric elements; implements tools to generate

and refine model meshes; reports accuracy by residue and error

estimate; analyzes interactions between fluids and solids, and

also contact with and without friction; frames Lagrangian, Eule

rian and AEL calculations; simulates statically, quasi-statically

or dynamically; and significantly parallelizes its calculations

to take advantage of parallel processing when available.

For thermal analysis, tochnog evolves the energy balance

equation. For fluids, the Stokes and Navier-Stokes. For solid

elasticity, the isotropy and transverse isotropy. For solid

elastoplasticity, the von Mises, Mohr-Coulomb and Gurson. For

solid hypoplasticity, the von Wolfersdorf, cohesion, intergranu

lar strain, and pressure-dependent initial void ratio. Also for

solids, the damage, thermal stress, hypoelasticity, viscoelastic

ity, viscoplasticity and viscosity. For ground water flow, the

storage equation. For general wave phenomena, the wave equation.

tochnog is an extensive numerical free-software package

whose operation extends far beyond that which a mere man page can

document. The TOCHNOG User's Manual and other documents found in

/usr/share/doc/tochnog/ give complete instructions on tochnog's

use.

INVOCATION

If the input-file name given on the command line contains

no "." dot, then the standard tochnog input filename extension

".dat" is implicitly appended to it (for example, "problem" is

interpreted as "problem.dat"). If omitted, input-file defaults

to "tn.dat".

It is usual to redirect tochnog's output rather than to

let it stream to the terminal. For example,

$ tochnog tn.dat >tn.out

OPTIONS

The instructions given in input-file control tochnog. The

tochnog command itself accepts no command-line options. See the

documentation in /usr/share/doc/tochnog/ for further information.

FILES

tn.dat the default input file
tn.run the runtime input file
tn.log the calculation message log
tn.dat, et al.

output files in various formats, suitable for plot

ting

tn.dbs the state database, containing full calculation

state data, including nodes, elements, solution fields, etc.
tn.dvd the step-by-step record of the evolution over time

of the model's unknown variables
tn.tmp a scratch file (do not use this name yourself)
tn.out conventionally, the file to which tochnog's stdout

is redirected (but the user controls this as described under

INVOCATION

/usr/share/doc/tochnog/

reference documents including the TOCHNOG User's

Manual (on a Debian system, found only when the tochnog-doc pack

age is also installed)

BUGS

Unknown. (This man page is contributed by a user unaffil

iated with tochnog development.)

AUTHOR

Dennis Roddeman <dennis.roddeman@feat.nl>

As of January 2001, the author asks that any error re

ports, questions, wishes, etc., be e-mailed to him at the address

given.

Thaddeus H. Black <t@b-tk.org> provided this man page.

SEE ALSO

gnuplot(1) (for plotting); gv(1) and lpr(1) (for viewing

and printing the .ps documents in /usr/share/doc/tochnog/).

SourceForge 17 August 2004

TOCHNOG(1)