Student projects in Materials Physics,
Västergårdgymnasiet & Chalmers


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:
  • 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.

    [plot of fiber stress factor versus fiber number]

  • Links back

    Elsebeth Schröder homepage, Chalmers
    Materials and Surface Physics Group, Chalmers
    Västergårdgymnasiet, Södertälje

    Revised April 25, 2001 by Elsebeth Schröder, schroder (at)