In mining and mineral processing, compressive loading is often encountered
during the comminution of ore bearing minerals and in the wear resistant materials
used in the comminution circuit. A common thread joining many of the materials that
are primarily used under compressive loading is the presence of a high modulus
reinforcement, either fiber or particulate, embedded within a lower modulus matrix
phase (i.e., a brittle heterogeneous material). Many of these heterogeneous materials
are designed or manufactured such that an imperfect interface (i.e., an interface that
provides less than complete coherency between the reinforcing phase and the matrix)
exists between the reinforcing phase and the matrix (e.g., tough fiber-reinforced
ceramics). To date, most research has focused on the response of these heterogeneous
materials with imperfect interfaces to tensile loading; however, little is known about
their response to compressive loading.
The principal objective of this investigation is to develop a better understanding
of the micromechanical behavior of these complex materials under compressive
loading. Analytical solutions are reviewed and compared with finite element models
for the simulation of heterogeneous materials with imperfect interfaces under
compressive loading. This comparison shows that a nonlinear numerical approach
(finite element method) is necessary to fully simulate the behavior of these materials.
To validate the nonlinear model, laser moire experiments were conducted on a model
heterogeneous material loaded under uniaxial and biaxial compression. In-plane
displacements were measured and found to be in fundamental agreement with the
nonlinear finite element model. Subsequently, finite element simulations were
developed for a variety of heterogeneous materials with imperfect interfaces. Results
show that deleterious tensile stress concentrations are primarily influenced by three
factors: (i) the nature of the imperfect interface, (ii) the moduli mismatch between the
reinforcement and matrix, and (iii) the volume fraction of the reinforcement.
Finally, crack initiation experiments in laboratory models of a heterogeneous
material with a frictional imperfect interface were conducted to substantiate the prior
work using nonlinear finite element models. Experimental results correlate well with
the numerically-predicted micromechanical behavior of a model heterogeneous system
under uniaxial compressive loading. / Graduation date: 1994
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/35609 |
| Date | 11 August 1993 |
| Creators | Laird, George |
| Contributors | Kennedy, Timothy C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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