Onome E. Scott-Emuakpor PhD, Senior Aerospace Engineer, US Air Force Research Laboratory
Small scale turbine engine performance is currently limited by available manufacturing capabilities. Though an engine redesign and/or the addition of complex components with novel cooling schemes has conceptually made it possible to improve thermal efficiency, fabrication of designs cannot be realized with conventional manufacturing approaches. Combining the lack of manufacturing options with the desire for improved small turbine engine performance has fueled the growing interest in laser and electron beam powder bed fusion manufacturing. With reasonable understanding of manufacturing process parameters, form and fit can be achieved with powder bed fusion. However, due to the uncertainty in the effects of features such as thickness, fillets, cooling holes, and build orientation, function (specifically structural integrity) of a small component cannot be simply validated by normal means of standardized mechanical testing. This gap in the ability to accurately assess structural integrity has led to the development of feature based fatigue testing at vibratory conditions representative of components in resonance during engine operation.