Prediction of acoustically induced random vibration loads for shuttle payloads

摘要

This paper presents a method for predicting random vibration loads for National Space Transportation System (NSTS) Shuttle launched payloads. Two methods for combining the random vibration loads with the lift off transient loads and combining the Finite Element Analysis (FEA) predictions with the Statistical Energy Analysis (SEA) predictions are also presented. The technique for predicting random vibration loads assumes the launch acoustic field is the dominate forcing function and that the significant structural load (stress) occurs in the low frequencies (below 200 Hz). Data from a laboratory acoustic test were used to validate this assumption. FEA was selected to predict the random vibration loads for both the primary and secondary structure up to 150 Hz. The 3sigma random vibration loads were then combined with the transient coupled and static acceleration loads to arrive at the total load in the structural members. The benefits of this approach include the use of identical dynamic and vibroacoustic finite element models and the ease of combining transient and vibroacoustic loads.