Evaluation of aircraft random vibration under roughness excitation during taxiing

Abstract

The assessment of runway smoothness or roughness is intimately tied to the vibrational response of aircraft during taxiing. In this study, employing the pseudo excitation method (PEM) based on random vibration analysis, we unearthed the relationship between the random vibrations of five distinct aircraft types and runway irregularities. Initially, we established two three-dimensional (3D) models of aircraft taxiing vibration and derived the response output under roughness excitation. Subsequently, we employed MATLAB to analyze the power spectral characteristics of the vibrational response in different parts of the aircraft. Lastly, we examined the effects of taxiing speed, aircraft type, runway roughness, and lift on the aircraft's vibration. Our findings indicate that the distribution of vibration power spectral density (PSD) exhibits multiple peaks, correlating with the degrees of freedom of the aircraft. We further note that the frequency that aligns most closely with the response peak should be the focus of investigation. High-frequency excitation impacts the pilot and nose landing gear more significantly than the passenger and main landing gear. Absent the consideration of lift, increased taxiing speed amplifies the impact of roughness excitation on aircraft taxiing safety. Larger aircrafts are more sensitive to long-wave roughness. With lift in consideration, all aircraft types exhibit a speed sensitivity to vibration, which should be the primary concern in runway roughness evaluations.

Keywords

• Random vibration
• Runway roughness excitation
• Pseudo excitation method (PEM)
• Sensitive speed