High Temperature/High Cycle Fatigue (HCF) Testing
Temperature & Cycle Fatigue Testing
High Temperature Fatigue Testing:
DTB has run a number of high temperature fatigue test programs, including the testing of parts for military and commercial aircraft, tanks, trucks, and automobiles. These tests are performed on various stator, compressor, and turbine blades, which can be fatigue tested at extreme temperatures of 400⁰F-1,800⁰F. These tests are also conducted using a hydraulic actuator, which is attached to the end of the blade using a clamp ring.
The machines that run these tests were developed here at DTB. Our machines serve as an improvement over the shaker-based system used at the OEM, since the tests are controlled using the actuator’s internal linear variable differential transformer (LVDT) for displacement control.
HCF testing is performed on a vibration shaker. This type of testing consists of mounting the base of the blade to a vibration plate; carefully tuning it in the resonant frequency at the desired mode frequency; and raising the amplitude to achieve the required stress levels. Calibration of the strain gages is critical for this test, since the high strain levels quickly fatigue the strain gages. The entire test is then controlled based on the blade tip displacement.
HCF testing is often required to run at elevated temperatures, which requires suspending heaters above the shaker, as well as cooling the vibration plate to protect the shaker head.