Chapter 1: INTRODUCTION

Chapter Contents:

• 1.1 Overview
• 1.2 General Features
• 1.3 Guide to the Manual
• 1.4 Installing
• 1.5 Compiling
• 1.6 Running

1.1 Overview

The development of FRIC2D was an integral part of Michele Cooke's Ph.D. work at Stanford University. In the course of her thesis she used this code to investigate several situations of frictional slip in the earth. This informal User's Manual was prepared by Michele Cooke and is based on the the user documentation developed by Jinhuo Liang for FRIC2D's parent BEM code, FRAC2D. Indeed, some parts of the code description are taken directly from the documentation of FRAC2D.

This document was created in HTML format. This format allows the user to more speedily access portions of the documentaion of interest. The HTML version can be accessed through the World Wide Web at URL: http://www.geo.umass.edu/~cooke/fric2d/doc.html. Lisa Koenig formatted many of the figures of this text and edited the text.

Version 2.0 of Fric2d allows a more broad range of superposed gravitational loading than version 1.0, wihch was limited to lithostatic loading.

1.2 General Features

1. The input data is based on recognized word commands that allow the user to identify the application of each command easily and in a logical fashion (e.g. the command, fracture, applies fracture conditions to the model).

2. The command and data are entered through a file-driven procedure (i.e. they are stored in a data file and read from a storage device).

3. The word-oriented input files provide an excellent means to keep a documented record of the analyses performed for an engineering study. Often, it is convenient to include these files as an appendix to an engineering report for the purpose of quality assurance.

4. The command-driven structure also allows the user to develop pre- and post-processing programs to manipulate FRIC2D input/output as desired.

1.3 Guide to the Manual

Beginner users who wish to create their own models might first read Chapters 3, 4 and 5 for sign conventions, elements, coordinate systems, units, and data file handling.

Users who are not familiar with the boundary element method and fracture mechanics should read Chapter 2 . A brief description of the theoretical background of FRIC2D is given in this chapter. Many of the sections in this chapter are identical to FRAC2D.

The complete description of all input commands is given in Chapter 4 . It is suggested that the user refer to Section 4.1 for a recommended sequence for entering input commands by function.

Post-processing of the results is described in Chapter 5 . The user can understand the self-explanatory output files and process the results using other commercial graphic-processing software.

1.4 Installing

fric2d.c

The main program, it is developed to read input data, to calculate stress and displacement fields, to predict fracture propagation, and to output the analysis results.

getopt.c

Links a list of arguments to the program based on the arg_string passed in.

getwords.c

Reads a line of input data into the character array line from the input file, then return the number of words on the line.

getopt.h

Header file for declaring the data used in fric2d.c, getopt.c.

1.5 Compiling

cc fric2d.c getopt.c getwords.c -o fric2d -lm

where cc is the name of your C compiler, is a space-separated list of the source files, including fric2d.c, getopt.c, getwords.c, and getopt.h; -o fric2d names the executable file to be created, and -lm is an option for linking with the math object library.

On many computers, a makefile may be used to simplify the process of compiling and maintaining FRIC2D. A simple makefile for a UNIX system is given as follows:

	# Makefile for compiling fric2d
	# Source files
	SRC = fric2d.c getopt.c getwords.c
	# Object files
	OBJ = fric2d.o getopt.o getwords.o
	# Options (Flags) to be used by the C compiler
	CFLAGS = -g -lm -I$(HOME) -sb
	# Library to be used
	LIB =
	# Name of the C compiler to be used
	CC = acc

	# Building the executive code fric2d based on OBJ
	fric2d:  $(OBJ)
		$(CC) -o fric2d $(OBJ) $(CFLAGS) $(LIB)

	# C verifier lint to examine source files for potential errors, 
portability problems
	lint: 	lint $(SRC)

1.6 Running

fric2d -i infile -o outfile -g graphicsfile

runs fric2d using infile as the input file, outfile as the file for the output data and graphicsfile as the file for the output graphics.

While FRIC2D is running, updates are printed to standard output. Information such as the current loading step and iteration of convergence are printed to standard output (usually the screen) This information informs the user about the progress of the process. The run information can be send to a separate file using the following command:

fric2d -i infile -o outfile -g graphicsfile > run.info

The file run.info will contain information about the process. When no input or output files are specified, FRIC2D reads from the standard input and writes to the standard output.

When FRIC2D encounters an error from which it cannot recover, it prints an error message to the standard output (normally the monitor) and ceases execution. If you don't know what the standard input and output are for your machine, consult the documentation for your C compiler. For example, suppose the first line of the input file, example.in, attempts to assign an unknown constant

no_such_constant = 100.0

If you run FRIC2D on a UNIX machine using example.in as input file, you will get the following results:

	Unix-prompt>fric2d -i example.in
	fric2d: Unknown constant, or incorrect format (badfile.in, line 1)
		  no_such_constant  =  100.0
	Unix-prompt>

References

Go to Chapter 2 , 3 , 4 , or 5