Analysis of Nonstationary Vibroacoustic Flight Data Using a Damage-Potential Basis

摘要

Traditional maximax analysis of nonstationary flight data for space and launch vehicles can overestimate peak response and does not address the potential for fatigue failure of hardware. A new method, referred to as the damage-based approach, is presented that employs an extended response spectrum analysis and includes amplitude-cycle counts. The outcome is a conservative, stationary test specification that envelops the damage potential of the nonstationary flight environment for both peak response and fatigue, while recognizing uncertainties in damping and the fatigue law. Notable features of the new analysis technique are a quantitative means for addressing fatigue-damage potential in flight and a reduction in the overestimation of peak flight responses. Damage-based analysis of flight data can, therefore, help define more appropriate test specifications from historical data. The new method also provides a more accurate means for assessing the qualification status of components following early missions of a new launch vehicle and may help avoid unnecessary requalification of hardware suggested by an over-conservative maximax analysis of flight data. Potential benefits of the damage-based approach are demonstrated by investigation of a vibration and an acoustic measurement from multiple flights of the Titan 4A launch vehicle.