Acoustic emission signal analysis to filter the noise during tensile tests on the aa2219 aluminum alloy tensile coupons and generation of signature corresponding to failure

Abstract

Aluminium and its alloys are found in wide range of engineering applications due to their exceptional properties. Though aluminium has low density, it is used as engineering structural material next to steel. Due to its low weight to strength ratio, it becomes an unavoidable material in the field of aerospace. AA 2219 is one of the aluminium alloy contain copper as main subsystem. Due to its exceptional weldability and low weight, propellant tanks of launch vehicles are manufactured by AA 2219. Such propellant tanks are always proof tested with the aid of acoustic emission technique to ensure its stability before its installation and during its operation. Acoustic Emission Testing (AET) is one of the latest techniques to detect damages and live crack growth of stressed structures and materials. Acoustic emission is the stress energy waves released from materials/structures under loading condition. Such waves are acquired and amplified with electronic circuits and stored as AE information. During the proof testing of aluminium propellant tanks, the tanks are pressurized with pneumatic medium to avoid contamination. While pressurizing the tanks, pneumatic jet from nozzle becomes the major spurious source during the acoustic emission data acquisition. Interpretation of such noise data regularly lead to incorrect prediction. Hence, it is essential to denoise the acquired AE data to improve the accuracy of failure prediction. Based on the geometrical characteristics acoustic emission signals are classified into burst and continuous emissions. Burst emissions are usually individual waves separated clearly in time but the continuous are not divided by time. This geometrical difference is found to be an efficient tool to distinguish the genuine crack related acoustic signals from noise signals. newline