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Full-Text Articles in Mechanical Engineering
A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart
A Hybrid Constitutive Model For Creep, Fatigue, And Creep-Fatigue Damage, Calvin Stewart
Electronic Theses and Dissertations
In the combustion zone of industrial- and aero- gas turbines, thermomechanical fatigue (TMF) is the dominant damage mechanism. Thermomechanical fatigue is a coupling of independent creep, fatigue, and oxidation damage mechanisms that interact and accelerate microstructural degradation. A mixture of intergranular cracking due to creep, transgranular cracking due to fatigue, and surface embrittlement due to oxidation is often observed in gas turbine components removed from service. The current maintenance scheme for gas turbines is to remove components from service when any criteria (elongation, stress-rupture, crack length, etc.) exceed the designed maximum allowable. Experimental, theoretical, and numerical analyses are performed to …
Thermomechanical Fatigue Life Prediction Of Notched 304 Stainless Steel, Justin Karl
Thermomechanical Fatigue Life Prediction Of Notched 304 Stainless Steel, Justin Karl
Electronic Theses and Dissertations
The behavior of materials as they are subjected to combined thermal and mechanical fatigue loads is an area of research that carries great significance in a number of engineering applications. Power generation, petrochemical, and aerospace industries operate machinery with expensive components that undergo repeated applications of force while simultaneously being exposed to variable temperature working fluids. A case of considerable importance is found in steam turbines, which subject blades to cyclic loads from rotation as well as the passing of heated gases. The complex strain and temperature histories from this type of operation, combined with the geometric profile of the …
Creep-Fatigue Crack Initiation And Propagation Of A Notched Stainless Steel, Scott Keller
Creep-Fatigue Crack Initiation And Propagation Of A Notched Stainless Steel, Scott Keller
Electronic Theses and Dissertations
Premature failures of vital gas turbine components, such as blades and vanes, have been the result of increasing demands of power generation facilities. As power needs fluctuate throughout the day, operators are quickly firing up gas turbines as a means of providing instant power. Traditionally, these engines run at constant operating conditions; however, contemporary operating conditions call for these engines to be applied on an “as necessary” basis. The result of the cyclic startup and shutdown of gas turbines has led to a phenomenon known as creep-fatigue (CF). A coupling of two primary failure mechanisms in gas turbines, CF conditions …