Engineering Commons^™

Inclusion Control In Steel Castings, Koushik Karthikeyan Balasubramanian

Masters Theses

“Non-metallic inclusions are mainly comprised of oxides, sulfides, and nitrides, and are formed in liquid steel during the melting and refining process, as a result of reoxidation, worn-out refractories, or entrained slag. The notch toughness of high strength steels is particularly susceptible to the type, number, size, and distribution of non-metallic inclusions. High manganese and aluminum austenitic steels, or Fe-Mn-Al steels, have gained much interest in the military and automotive sector because of their excellent combinations of high strength and toughness. However, these steels are subject to both oxide bifilms and aluminum nitride, AlN, inclusions which form during melting and …

Preformed Partial Gel Injection Chased By Low-Salinity Waterflooding In Fractured Carbonate Cores, Ali K. Alhuraishawy, Baojun Bai, Mingzhen Wei, Abdullah Almansour

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

Fractures and oil-wet conditions significantly limit oil recovery in carbonate reservoirs. Gel treatment has been applied in injector wells to modify the prevailing reservoir streamlines and significantly reduce fracture permeability, whereas low-salinity waterflooding has been applied experimentally to modify rock wettability toward water-wet for improved oil recovery. However, both processes have limitations that cannot be resolved using a single method. The objective of this study was to test whether low-salinity water could enable gel particles to move deeply into fractures to efficiently increase oil recovery and control water production. A semitransparent fracture model of carbonate cores and acrylic plates was …

In Situ Mechanical Characterization Of The Mixed- Mode Fracture Strength Of The Cu/Si Interface For Tsv Structures, Chenglin Wu, Congjie Wei, Yanxiao Li

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In situ nanoindentation experiments have been widely adopted to characterize material behaviors of microelectronic devices. This work introduces the latest developments of nanoindentation experiments in the characterization of nonlinear material properties of 3D integrated microelectronic devices using the through-silicon via (TSV) technique. The elastic, plastic, and interfacial fracture behavior of the copper via and matrix via interface were characterized using small-scale specimens prepared with a focused ion beam (FIB) and nanoindentation experiments. A brittle interfacial fracture was found at the Cu/Si interface under mixed-mode loading with a phase angle ranging from 16.7° to 83.7°. The mixed-mode fracture strengths were extracted …

Effect Of Reservoirs Heterogeneity On Injection Pressure And Placement Of Preformed Particle Gel For Conformance Control, Ze Wang

Masters Theses

"Preformed particle gels (PPG) have been successfully applied as a plugging agent for plugging fractures and then divert displacing fluid into poorly swept zones. However, PPG propagation and plugging mechanisms through open fractures have not been studied thoroughly.

This work investigated the influence of some factors (particle size, brine concentration, heterogeneity, and brine salinity) on gel injectivity, plugging performance for water flow through open fractures. Five-foot tubes were used to mimic open fractures. Three models were designed to conduct the work, including (1) single fracture with uniform fracture width, (2) single fracture with different widths, and (3) two parallel fractures …

A First-Principles-Based Model For Crack Formation In A Pressurized Tank Following An Mmod Impact, William P. Schonberg, J. Martin Ratliff

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Most robotic spacecraft have at least one pressurized vessel on board, usually a liquid propellant tank. One of the design considerations of such spacecraft is the anticipation and mitigation of the possible damage that might occur from on-orbit impacts by micro-meteoroids or orbital debris (MMOD). While considerable effort has been expended in the study of the response of non-pressurized spacecraft components to MMOD impacts, relatively few studies have been conducted on the pressurized elements of such spacecraft. In particular, since it was first proposed nearly 45 years ago, NASA's current evaluation methodology for determining impact-induced failure of pressurized tanks has …

Theory For Dynamic Longitudinal Dispersion In Fractures And Rivers With Poiseuille Flow, Lichun Wang, M. Bayani Cardenas, Wen Deng, Philip C. Bennett

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

We present a theory for dynamic longitudinal dispersion coefficient (D) for transport by Poiseuille flow, the foundation for models of many natural systems, such as in fractures or rivers. Our theory describes the mixing and spreading process from molecular diffusion, through anomalous transport, and until Taylor dispersion. D is a sixth order function of fracture aperture (b) or river width (W). The time (T) and length (L) scales that separate preasymptotic and asymptotic dispersive transport behavior are T = b²/(4D _m), where D_m is the molecular diffusion …

Failure Investigation Of The Steel Strut Of Paseo Suspension Bridge, Genda Chen, Chris Courtright, Lokeswarappa R. Dharani, B. Xu

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A vertical strut of the 1232-foot long, self-anchored Paseo Suspension Bridge fractured when the temperature hit at a record low of 9°F below zero. During inspection the following day, it was found that its lower pin was frozen and did not allow for free movement of the superstructure. The objective of this study is to pinpoint one of the four reasons for this incidence or their combination: overstressing, thermal contraction, fatigue, and reduction in fracture toughness at low temperatures. To achieve this objective, material property and fatigue testing was performed on samples of strut material while the bridge and strut …

Surface Fracturing Of Armatures Within Helical Flux-Compression Generators, Paul Nicholas Worsey, Jason Baird

Mining Engineering Faculty Research & Creative Works

Tubes of aluminum and of copper filled with C-4 high-explosive were tested during this study of high strain rate effects within thin metallic structures performed as an adjunct to helical flux-compression generator research at the University of Missouri-Rolla. Focusing on the stresses within a relatively thin metallic structure when brisant explosives abutting the structure are detonated, this study directly affects the understanding of flux cutoff and high strain-rate resistivity changes in an expanding armature. The detonation wave is compressive, and the shock waves resulting from its transmission into a thin metallic structure cause both compressive and tensile regions, posing an …