Experimental Modal Analysis for Aerial Centerline Fuel Tanks

Abstract

External aerial fuel tanks are attached to the aircraft to extend their range and endurance. This experimental study presents a meticulous investigation into the dynamic characteristics of aerial fuel tanks A and B, employing resonance search tests and frequency sweep tests. The experimental setup, involving cyclic excitation and
vibration analysis, aimed to predict and compare the tanks' natural frequencies, mode shapes, and structural damping. The acquired data revealed striking similarities in dynamic behavior, affirming that both tanks exhibit consistent responses to external forces. The structural damping values, mode shapes, and resonant frequencies closely aligned, indicating negligible variations in geometry, material, and production technology. The increase in natural frequencies with mode number reflects enhanced structural stiffness and responsiveness. The comprehensive analysis supports the conclusion that tank B is well-prepared for flight testing, showcasing its stability and reliability in dynamic conditions as tank A passed already the flight test.