Engineering Commons^™

An Investigation Of The Through-Thickness Stress Intensity Factor Using P- And H-Element Finite Element Analysis, Christopher Castle

Theses and Dissertations

The stress intensity factor is used in fracture mechanics to characterize the stress state near the crack tip in a structure under remotely applied loads. The magnitude of the stress intensity factor is dependent on geometry, the size and location of the crack, and the magnitude and distribution of loads on the structure. The scope of this thesis is the study of the through-thickness stress intensity factor using two different FE approaches. P- and h-element finite element methods are used to study the stress intensity factors. The accuracy of the predicted Mode I stress-intensify factor (K_I) is assessed …

New Framework And Decision Support Tool To Warrant Detour Operations During Freeway Corridor Incident Management, Jing Mao

Theses and Dissertations

As reported in the literature, the mobility and reliability of the highway systems in the United States have been significantly undermined by traffic delays on freeway corridors due to non-recurrent traffic congestion. Many of those delays are caused by the reduced capacity and overwhelming demand on critical metropolitan corridors coupled with long incident durations. In most scenarios, if proper detour strategies could be implemented in time, motorists could circumvent the congested segments by detouring through parallel arterials, which will significantly improve the mobility of all vehicles in the corridor system. Nevertheless, prior to implementation of any detour strategy, traffic managers …

Effects Of Phosphate On The Transport Of Escherichia Coli In Saturated Quartz Sand, Nan Chen

Theses and Dissertations

Bacterial deposition and survival in porous media is a crucial phenomenon in various environmental processes including bioremediation, water treatment, and pathogen contamination. The fate of bacteria in porous media may be greatly influenced by ionic strength and phosphate. Although phosphate is widespread in the natural environment, the influence of phosphate on the transport of three strains of ESCHERICHIA COLI O157:H7 cells in the groundwater system remains unknown.

Experiments were performed in saturated sand packed columns with and without phosphate to examine the transport of bacteria, deposition rate coefficient, interaction energy between bacteria and sand, and bacteria surface charge.

Experimental results …

Smart Carbon Nanotube/Fiber And Pva Fiber-Reinforced Composites For Stress Sensing And Chloride Ion Detection, Joshua A. Hoheneder

Theses and Dissertations

Fiber reinforced composites (FRC) with polyvinyl alcohol (PVA) fibers and carbon nanofibers (CNF) had an excellent flexural strength in excess of 18.5 MPa compared to reference samples of 15.8 MPa. It was found that the developed, depending on applied stress and exposure to chloride solutions, composites exhibit some electrical conductivity, from 4.20x10^-4 (ohm*m)^-1 to. 4.13x10^-4 (ohm*m)^-1. These dependences can be characterized by piezioresistive and chemoresistive coefficients demonstrating that the material possesses self-sensing capabilities. The sensitivity to stain and chloride solutions can be enhanced by incorporating small amounts of carbon nanofibers (CNF) or carbon nanotube (CNT) into composite structure. Conducted research …