Impact induced composite delamination: state and parameter identification via joint and dual extended Kalman filters

We present and compare the joint and dual variants of the extended Kalman filter for coupled state and parameter identification problems. With reference to nonlinear dynamics of layered composites, we assume that the elastic properties of the laminae are known, whereas the softening constitutive law of the interlaminar phases adopted to simulate delamination needs to be calibrated. Purpose of this study is the identification of the interlaminar model and of the debonding surface(s) on the basis of free-surface measurements only. We show that, in the case of a dominant dilatational wave propagating in the through-the-thickness direction of the laminate, the free-surface displacement can be weakly sensitive to some constitutive parameters, and the relevant model calibration is not performed optimally. As far as delamination detection is concerned, the dual filter performs by far better than the joint filter, particularly in noisy environments.