Understanding the behavior of geomaterials under explosive loading is essential for several applications in the mining and oil industry. To date, the design of these applications is based almost solely on empirical equations and tabulated data. Optimal designs require accurate and complete knowledge of rock behavior under various loading conditions. The vast majority of the properties available in the literature have been gathered by deforming the specimen slowly. These properties have been used to establish constitutive models which describe the behavior of rocks under static and quasi-static loading conditions. However, the dynamic properties and material constitutive models describing the behavior of geomaterials under high strain-rate loading conditions are essential for a better understanding and enhanced designs of dynamic applications. Some attempts have been made to measure dynamic properties of rocks. Also, some trials have been made to devise material models which describe the behavior of rocks and the evolution of damage in the rock under dynamic loading. Published models were successful in predicting tensile damage and spalling in rocks. However, there are no established models capable of predicting compressional damage in rocks due to dynamic loading. A recently-developed model, the RHT model, was formulated to describe the behavior of concrete over the static and dynamic ranges. The model was also formulated to predict compressional damage based on the strain rate at which the material is subjected to. The RHT model has been used successfully in several applications. The purpose of this research was to characterize one rock type as an example of a hard brittle rock. The physical properties of the rock as well as the static and dynamic mechanical properties were investigated. These properties were used to calibrate the RHT model and investigate its potentials to predict compressional damage in brittle materials. The calibrated model showed good precision reproducing the amplitude of the strain signals generated by explosive loading. It was also capable of predicting compressional damage with acceptable accuracy. Unfortunately, due to implementation restrictions, tensile and spall damage could not be captured by the model. The duration and shape of the strain pulse were also poorly modeled. / Thesis (Ph.D, Mining Engineering) -- Queen's University, 2010-12-22 17:54:05.887

The objective of this study is to investigate the penetration and perforation resistance of alumina ceramics against kinetic energy projectiles. There are several different mechanisms by which a target can fail when it is subjected to impact of a projectile and these may occur singly or in combinations of two or more. The presence of large number of penetration and failure mechanisms makes the investigation of the perforation very difficult. Because of this difficulty, the analytical investigations of penetration and perforation processes usually assume one type of failure mechanism. One of these analytical investigations is reviewed and it is seen that this analytical model is capable of predicting after impact parameters reasonably accurately. A parallel investigation of this problem is also been carried out numerically by using Autodyn hydrocodes. Numerical study is capable of simulating the main changes in ceramic/steel composite target during penetration process of kinetic energy projectile. Results of analytical and numerical investigations are parallel to each other. A set of experiments was carried out for checking the results of analytical and numerical calculations with the experimental data.

The objective of this study is to investigate the detrimental effects of a flexible linear shaped charge (FLSC) to variable thickness back and constant thickness front plates due to varying backspace distance. A FLSC is used to cut both metallic and non-metallic material, quickly and efficiently. It is flexible and may be formed to produce cuts of many configurations, thereby making it particularly useful where more conventional cutting techniques are difficult to employ. While performing its function, the FLSC gives some damage to the back due to the high transient pressure and fragmentation effects. In order to decrease this damage, a steel plate is placed behind the FLSC. In this work, a numerical analysis is carried out by using Autodyn Hydrocode for the investigation of the extent of the plastic deformation of the back as well as front plates for varying backspace distance of the steel plate having different thicknesses. The numerical results are then compared with the experimental findings. The flexibility property of the FLSC is not used in this study. Only the straight segment of FLSC is used.