Relevancy and Pay-offs Preliminary design of airframe structures to the

1. X ASTROS O CAP-TSD (Linear) ◊ CAP-TSD (Non-Linear) Mr. Srinivasan Janardhan, Mr. Chakradhar Byreddy, Dr. Ramana V. Grandhi Dr. Philip Beran, Dr. Frank Eastep, Dr. Narendra Khot, Dr. Brian Sanders Aerodynamic Model Structural Model Research Objectives • Analyze the sensitivity of flutter speed and LCO to store structural parameters in the transonic regime • Develop a multidisciplinary optimization methodology to delay store-induced flutter Vibration and Static Analysis using ASTROS Splined Mode shapes Static Analysis using CAP-TSD Increase the number of iterations Static Solution Converging ? • Relevancy and Pay-offs • Preliminary design of airframe structures to the new and existing air vehicles • Automated analysis for multiple configurations and flight conditions • Simulation-based design approach • Facilitates “Certification by Analysis” by using higher fidelity models • Reduced computational cost and time No Use higher dynamic pressure Yes Dynamic Aeroelastic Analysis Is the Solution stable ? Yes No Flutter occurs; Determine flutter conditions , damping Sensitivity Analysis & Design Optimization Store center of gravity locations Fore Aft c.g. of underwing store @ 22 % of aerodynamic root chord c.g. of underwing store @ 44 % of aerodynamic root chord c.g. of underwing store @ 66 % of aerodynamic root chord Aerodynamic Center@ 25% of aerodynamic root chord c.g. of tip store @ 32.5 % of aerodynamic tip chord Elastic Axis @ 33% of aerodynamic root chord c.g. of tip store @ 40 % of aerodynamic tip chord c.g. of tip store @ 50 % of aerodynamic tip chord Sensitivity of Flutter and Limit-Cycle Oscillation of an Aircraft Wing with Multiple Store Configurations Research Methodology Wing/Underwing store model Wing/Tip store model • Moving the store center of gravity aft reduces the flight envelope in the transonic regime CAP-TSD model • Flutter speed increases as the • pylon length decreases • Flutter speed decreases as the store is moved along the span • LCO onset speed decreases significantly • with increase in store mass • Inclusion of store (tip and underwing) aerodynamics does not have significant influence on flutter speed