Abstract: Gas turbine rotor spins at a very high speed under maximum operating conditions. Turbine casing needs to contain the blade under the blade-off condition. This is one of the most critical design and qualification criteria in structural design of a aircraft engine. High strain rate tests have been carried out at various strain rates (1000 sec-1 – 3000 sec-1) including quasi-static condition at various temperature (RT to 400oC) to assess the casing containment capability under blade off condition. Nickel base wrought super alloy Superni-718, the alloy for compressor and turbine casing has been tested in two heat treated conditions, solution treated (ST) and aged (STA) using Split Hopkinson Pressure Bar System under compressive mode and with Servohydraulic tensile testing machine in tensile mode. A comparison of the test results at different strain rate and temperature conditions is made with quasi-static test results to understand the change in material response under dynamic loading condition. Geometrical size of test specimen for Hopkinson Bar test has been varied to study the effect of L/D ratio, L is the specimen length and D is the diameter.
Authors: Anuradha Nayak Majila, Sudhanshu Sharma, Chandru Fernando, Vivek M. Chavan, Narendra Babu, R.J. Patel, and S.L. Mannan
Keywords: Su-718, Split Hopkinson Pressure Bar System, High Strain Rate Behavior. Stress-Strain Curve, Strain Hardening Exponent, Solution Treatment, Aging, Thermal Softening