Access Type

Open Access Embargo

Date of Award

January 2014

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Mechanical Engineering

First Advisor

Trilochan Singh

Second Advisor

Joon S. Lee

Abstract

Physical tests involving full-scale systems subjected to blast loads are expensive. The development of more accurate computational and analytical methods to better understand and predict the mechanics of mine blast phenomena could be used to reduce the cost of development of mine protected vehicles and protective equipment for personnel involved in demining and similar activities.

Although the science associated with air blast and blast-related ground shock phenomena is very extensive, that of mine blast, involving explosives buried in soil, is less well developed. In this work, theoretical, experimental, and computational methods are synthesized to better understand some of the mechanisms that affect the way that an explosive charge, buried in a bed containing soil or water, might affect a structure located above and in proximity to the surface of the bed.

For some loading regimes, the flow of soil as it is ejected from the surface of a blast crater is important. This work first examines the behavior of a bed containing sand-like particles suspended in air by virtue of the flow of the air. A computational technique, using finite differences, was developed to solve the equations of motion for the fluidized bed. The method was applied to predict Couette flow and compare the predictions with published experimental results. This technique was further applied to predict the sensitivity of the flow to the sphericity and size of the fluidized particles.

Next, experiments were examined which involved momentum transfer from buried gram scale explosive charges to rigid structures initially suspended above the surface of the water or soil. Associated computations were performed using an arbitrary Lagrangian Eulerian (ALE) finite element method. The constitutive behavior of the several types of soil involved in the work was defined by means of characterizations using high pressure (hundreds of millions of Pascal) uniaxial and triaxial tests at various initial combinations of water content and density; the associated computations were validated using results from blast experiments.

Various trends, sensitivities, and parametric relations, with significant practical importance, were analyzed and reported. Finally, there were analyses of experiments and computations involving momentum transfer to the bottoms of structures with various topologies.

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