Thermomechanical Fatigue Testing System

Thermomechanical fatigue analysis studies how cyclic thermal loading and large operating temperature gradients cause material fatigue. Test equipment often uses induction as a heat source, which makes systems expensive and difficult to analyze, so the team set out to find an alternative heat source. Using combustion heating and forced convection cooling, the team has devised a way to simulate real, accurate thermomechanical fatigue conditions at a fraction of the cost. The design optimizes the geometry of a nickel-based superalloy specimen to achieve a target stress of 80,000 psi and temperature of 2,100 degrees Fahrenheit when heated and cooled simultaneously. The method involves heating the top face of the specimen with a high-temperature oxy-propane torch while a vacuum draws air through a slot in the specimen at extremely high velocity. Simultaneous heating and cooling produces a temperature gradient between the top and bottom of the specimen, causing it to expand and compress at the same time, thus creating the desired compressive stress. This method will allow the sponsor to efficiently and cost-effectively explore thermomechanical fatigue properties of proprietary materials for future use in jet turbine engines.