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Full-Text Articles in Mechanical Engineering
Evaluation Of High Velocity Wear, Armando Deleon
Evaluation Of High Velocity Wear, Armando Deleon
Theses and Dissertations
The HHSTT located at Holloman Air Force Base conducts hypersonic testing in a unique way. Rather than perform cost prohibitive flight testing or hypersonic wind tunnel testing, a rocket-powered sled propels test articles down a track. This test setup has been used to test at speeds up to 2885 m/s (~Mach 8.6). The sled is kept on the rails by utilizing slippers, fabricated to wrap around the rail [1]. This slipper design keeps the sled from separating from the rail during a test due to the airflow producing lift, in a designed effort to minimize the wear that occurs during …
Effects Of Shot-Peening On High Cycle Fretting Fatigue Behavior Of Ti-6al-4v, Halil I. Yuksel
Effects Of Shot-Peening On High Cycle Fretting Fatigue Behavior Of Ti-6al-4v, Halil I. Yuksel
Theses and Dissertations
Effects of Shot-peening on High Cycle Fretting Fatigue behavior of Ti-6Al-4V were investigated. Experiments were performed with 6.35 mm thick specimens which provided S/N curves. After the tests, it was observed that the specimens failed near the trailing edge of contact. Scanning Electron Microscopy showed that cracks initiated on the contact surface for 6.35 mm, and at the depth of specimen ranging from 200 to 300 microns for 3.81 mm thick specimens. Initial crack orientation was around 37 and 42 degrees respectively for 6.35 and 3.81 mm thicknesses. Finite Element Analysis (FEA) was conducted, and using FEA results, Smith-Watson-Topper, Findley, …
Fretting Fatigue Behavior Of A Titanium Alloy Ti-6al-4v At Elevated Temperature, Onder Sahan
Fretting Fatigue Behavior Of A Titanium Alloy Ti-6al-4v At Elevated Temperature, Onder Sahan
Theses and Dissertations
The purpose of this research is to investigate the fretting fatigue behavior of the titanium alloy Ti-6Al-4V at elevated temperature is investigated. Fretting and plain fatigue experiments are conducted at 260 °C. Crack initiation location and crack initiation orientation is measured and fretting and plain fatigue life data of the specimens from these tests are obtained. Fatigue parameters capable of predicting the number of cycles to specimen failure, the crack location and the crack orientation along the contact surface are analyzed. The parameters are calculated by using the computed stresses and strains obtained from the finite element analysis. The mechanisms …
Examination Of Contact Width On Fretting Fatigue, Russell S. Magaziner
Examination Of Contact Width On Fretting Fatigue, Russell S. Magaziner
Theses and Dissertations
The primary goal of this study was to find the effects on the fretting fatigue life when systematically holding the fretting fatigue variables, peak contact pressure, maximum/minimum nominal bulk stress, and the ratio of shear traction to pressure force constant while varying the contact semi-width through changes in pad radius and normal load. Experimental tests were performed on a test setup capable of independent pad displacement. Analytical and finite element simulations of the different experimental tests were performed. The local mechanistic parameters were inspected. Five different critical plane based fatigue predictive parameters lacked effectiveness in predicting changes in life with …