Engineering Commons^™

The Use Of Shaped Explosive Charges To Investigate Permeability, Penetration, And Fracture Formation In Coal, Dolomite And Plexiglas, Calvin J. Konya

Doctoral Dissertations

"The concentration of methane gas which exists in the exhaust air from a coal mine is critical. It can be controlled by dilution of the gas with fresh air or by the regulation of the rate of methane emission into the mine workings. Degasification techniques which control the emission rate are currently being developed. The use of shaped charges to initiate fractures in coal and increase the gas flow rate was the object of this research. The three areas of investigation were: 1) permeability changes in coal models after fracturing with shaped charge jets, 2) fracture formation in coal and …

Deformation And Fracture Of Concrete Under Uniaxial Impact Loading, Esteban Eulogio Miranda

Doctoral Dissertations

"Stress wave propagation and interaction in plain concrete leading up to spall fracture was investigated experimentally with a computer numerical analysis of the bar-geometry axial-impact loading. The critical normal fracture strain energy U and mechanical energy W criteria are proposed for the spatial and time dependence explanation of spallation in concrete. The energy criteria are special cases of a more generalized cumulative damage model of the form:....

Finite-difference analyses of the wave propagation and interactions in the split Hopkinson bar showed that early failure in brittle materials limits the application of the conventional method of analysis because equilibrium in the …