Student projects in Materials Physics,
Västergårdgymnasiet & Chalmers
Projects
Two projects have been started, Fiber breaking
and Grain growth.
Fiber breaking
Here I have collected a few links (more to come)
to sites that have information relevant for
fiber breaking in composite materials. You may use them as inspiration.
However, some of the sites consider systems that are different
from the systems we study, others emphasize problems that we are not going
to consider.
As always, use your critical sense.
A project on matrix
cracks (that occur when stress is applied perpendicular to the fiber
direction)
Pictures of SiC fibers
A very short
introduction to composites
A few pages on how to experimentally test the breaking of composite materials,
taken from a course on
Ceramic Matrix Composites:
Apparatus,
Test specimen
What makes
materials hard, brittle, or good electrical conductors?
Grain growth
grain growth (from a different type of simulation)
What makes
materials hard, brittle, or good electrical conductors?
Information and files
Sample Fortran program, with comments:
testprogram.f
declar.fh
numbers.dat
For random-number generators check
"Numerical Recipes"
online and
information
(requires Acrobat Reader) on the random number generators
in Fortran77.
"Numerical Recipes"
also has the same subroutines and functions in C++.
The BIS subroutine (in fortran) for the fiber group.
The program needs the two subroutines from Numerical Recipes
dlubksb.for and
dludcmp.for for solving a system of linear
equations (these two subroutines can be found in C++ at
"Numerical Recipes").
I did not yet have time to rewrite the BIS subroutine in C++, but the
structure is relatively simple and the translation should not cause too many
problems, if you decide to do the translation.
Below I plotted the fiber stress concentration factor for the central
41 fibers in a patch with 7 broken fibers (fibers number
-7, 1, 2, 3, 4, 5, and 6). The broken fibers have no stress (stress factor=0),
and fibers far away from broken fibers have almost unchanged stress (stress
factor = 1). But unbroken fibers that are close to broken fibers (e.g.
fibers number -8 and 7) have an increased stress (stress factor > 1)
because they "take over" a large part of the stress that the broken fibers
should have carried.
Notice that the fiber stress factor multiplied by the applied stress (denoted
by x in the Beyerlein and Phoenix 1997 paper) is the fiber stress. If the
fiber stress for a particular fiber becomes larger than the failure stress
of the fiber the fiber will break.
Links back
Elsebeth Schröder
homepage, Chalmers
Materials and Surface Physics
Group, Chalmers
Västergårdgymnasiet,
Södertälje
Revised April 25, 2001 by
Elsebeth Schröder, schroder (at) fy.chalmers.se