INPUT FORCE RECONSTRUCTION USING A TIME-DOMAIN TECHNIQUE

A time domain method is presented for estimating the discrete input fo rces acting on a structure based upon its measured response. The struc ture is essentially transformed into its own loads transducer. A set o f inverse system Marker parameters, in which the roles of input and ou tput are reversed, is estimated from forward system Marker parameters using a linear predictive scheme. Inputs and acceleration outputs are assumed to be collocated to maintain minimum phase. Subsequently, any set of measured operational sensor data of any time duration can be co nvolved with the inverse Markov parameters to produce estimates of the input forces. This problem is ill-posed, so a regularization techniqu e is employed to stabilize computations. A stability analysis is perfo rmed to illustrate the effects of the regularization. Predicted pseudo -forces qualitatively approximate the actual input forces and, when ap plied back to the structure, produce accelerations which accurately ma tch the measured operational sensor data.