| Despite their technological importance, the understanding of the deformation mechanisms of particulate systems as well as the amount of information on material properties is still limited. Generally, the material properties are determined using shear testing, yet in order to predict the bulk material response during storage or transport, data corresponding to a variety of deformation, loading conditions, and shear rates are needed.; The main goal of this dissertation was to investigate the mechanical behavior of silica powder under general loading conditions and use or develop a model capable of predicting the observed behavior. Monotonic and cyclic confined compression tests were performed. The test results showed a strong non-linearity and stress-path dependency of the response. Elastic/plastic models were applied to silica. The simulation results show that a good agreement with data can be obtained only if hardening is taken into account. Modifications to existing theories were proposed resulting in an improved accuracy. Another objective of this dissertation was to provide a protocol to be used in industry for characterization and modeling of the behavior of new systems. An industrial system, polyethylene pellets, was studied. It was shown that only one hydrostatic and two confined compression tests are sufficient to characterize the deformation and failure behavior of the material and determine the model parameters. Comparison of results showed close agreement between theory and experimental data, thus demonstrating that the approach taken is very useful in predicting the behavior of industrial systems for general loading conditions. |
