Mechanical Engineering Commons^™

Trampoline And Bungee Fatigue-Test Machine, Andy Brock, Christopher D'Elia, Ryan Murphy

Mechanical Engineering

JumpSport, a Saratoga based recreational and fitness trampoline company, sponsored this senior project team towards the development of a fatigue-testing machine. The goal of this project was to iterate the previous machine JumpSport used for bungee cord, spring, and trampoline fatigue testing. Since minimal study had been conducted on these specific bungee cords, the fixture was designed to confirm the theoretical correlations for rubber and perform the final tests according to a strict protocol. Operating with a specific test protocol in mind will allow the data from multiple tests to be combined and analyzed statistically. With a design concept in …

Rebounder Fatigue Test Machine, Caroline Reeves, Will Robertson, Ethan Flory

Mechanical Engineering

JumpSport, a company that designs and sells trampolines and trampoline accessories, has sponsored this senior project team to design, build, and test a trampoline fatigue test machine. The machine must simulate a person jumping on the trampoline to test the life of JumpSport’s fitness trampolines and kids’ trampolines. Partway through the design process, the objectives were altered and this senior project team was tasked with merging with another Cal Poly senior project group to create an all-inclusive test machine to accommodate both full-trampoline testing and individual bungee cord testing.

The final design is centered on a slider crank linkage driven …

Effect Of Total Awake Time On Drivers' Performance And Evaluation Of Training Intervention To Mitigate Effects Of Total Awake Time On Drivers' Performance, Abd Malek Abdul Hamid

Open Access Dissertations

Driving while sleepy, drowsy or fatigued are leading contributors to road crashes. Sleepiness, drowsiness and fatigue usually occur at the end of a prolonged period of time during which an individual has been awake. Although these factors have been heavily researched, it is not clear how one of their primary causes, a prolonged total awake time (TAT), might affect driving skills such as hazard anticipation, hazard mitigation and attention maintenance, three skills that are crucial for safe driving.

The first experiment investigated how these three driving skills are affected by prolonged TAT, and if so to what extent. Forty-eight participants …

Mechanical Testing And Design Of The Magnetic Linear Test Apparatus, Sam Barker, Eric Rhoads, Brittni Blessie, Zachary Harris, Courtney Hollar

College of Engineering Poster Presentations

In order to further understand the fatigue and electrical properties of multifunctional magnetic shape memory alloys (MSMA), such as nickel-manganese-gallium (Ni-Mn-Ga), it is often necessary to modify existing machinery or design unique devices. The existing linear test apparatus has accomplished the goal of straining specimens by applying linear compression in a static magnetic field. The data acquired by this apparatus has been useful, but is limited by the device’s lack of magnetic field strength variability and closed loop control, as well as its data acquisition speed. The proposed study seeks to design and test a linear test apparatus that performs …

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

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

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 …