Test Devices Successfully Conducts High Cycle Fatigue Blade Testing at Elevated Temperatures

September 19, 2011

Hudson, Mass. – Commonly, high cycle fatigue (HCF) evaluation of blades is done through a traditional method such as vibrating the blades on a shaker table. Massachusetts-based Test Devices, Inc. recently bucked convention by demonstrating their unique APG technique to perform HCF tests in high-temperature conditions to evaluate advanced new blade designs. Test Devices’ ability to excite blades to prescribed resonance modes, while rotating at elevated temperatures allows a more realistic way for OEM’s to evaluate the durability and behavior of the actual blade design.

One of the most popular HCF test methods is Test Devices’ patented Liquid Jet Excitation, which uses atomized oil to produce the desired engine modes or vibratory conditions. This method can produce substantial blade response and a high degree of resulting strain, but its operable temperature is limited to 400 – 450°F. Test Devices’ APG method uses the pumping action of the blades in partial atmosphere and can be employed with additional external heating to allow testing in an elevated temperature condition that is a more realistic representation of the operating condition of the blades.

The APG technique provides a good method for evaluating emerging blade designs with high-temperature materials and coatings. Additionally, because this technique can be designed to evaluate the whole rotor-blade assembly, it can be a very useful test to evaluate damper effectiveness, dynamic response of the assembled hardware and coatings; especially for the systems that may exhibit different performance over a temperature range.

Dr. Hiro Endo, chief technology officer at Test Devices, commented: “Dynamic Spin Rig testing at Test Devices provides unique insight into the dynamic behavior of the bladed rotor assembly. Together, with the knowledge gained from more traditional forms of blade tests and analyses data, Dynamic Spin Rig (HCF) testing can offer more comprehensive validation of analytical methods and blade designs. The Dynamic Spin Rig can test the actual blade design with a true boundary condition of the blade (as assembled to the disk rim), while applying and independently controlling the centrifugal and vibratory loads, temperature and atmospheric elements. This capability allows the engineers and scientists to examine influence of the range of factors that affect the integrity and durability of the bladed rotor assembly in a more ‘pure form’ that reflects the condition in the operating gas turbine engines.”

About Test Devices
For over 30 years, Test Devices, Inc. has been the world’s premier source for rotational testing equipment and services. Test Devices provides advanced technology spin testing services to customers in a wide variety of industries. The company works with developers and producers of high-speed rotational components of jet engines, gas turbines, medical centrifuges, machine tools, industrial compressors, and high-speed electric motors, among others. For more information contact David Woodford at +1-978-562-4923, woodford@testdevices.com, or visit www.testdevices.com.