ABSTRACT
A frequency-domain system identification method is proposed to estimate both stiffness and mass parameters using measured modal information, which is different from usual system identification algorithms estimating stiffness parameters only. The structural parameters are estimated by minimizing the output error between measured and computed modal displacements at the limited degrees-of-freedom. The output error vector emi(x,y)(Nm × 1) of mode i is defined by Equation 1.
where Bm(Nm × N ) = Boolean matrix composed of 0’s and 1’s to select measured degreesof-freedom, m(x,y) =K(x) − λmi[ 0m Mu(y) ], Im(Nm × Nm) = identity matrix, φmi(Nm × 1), φui(Nu × 1) = measured and unmeasured parts of the ith modal displacement vector, and Nm, Nu = number of measured and unmeasured degrees-of-freedom, respectively. A nonlinear constrained optimization problem was formulated and solved for optimal parameters.
