Estimation of Unsteady Loading for Sting Mounted Wind Tunnel Models

§Measurement of static loads is conventionally performed using a linear combination of strain gage measurements. For the case of a loading environment with energy content in the same frequency band as structural modes, measurements can be significantly corrupted. In this development, a method for accurately estimating the spectral content of an applied loading is presented. This is accomplished by performing system identification on the structural dynamic system using a prescribed forcing function. A linear filter is developed based on the identified plant that converts measured strain and acceleration data to an estimate of applied loads. Analytical and experimental results are presented for a simple structural dynamic system subjected to a prescribed forcing function.