We are pleased to announce the monograph "Nieparametryczna metoda identyfikacji zmian masy i sztywności konstrukcji" (Nonparametric identification of structural mass and stiffness modifications) by Grzegorz Suwała (IPPT Reports 4/2016).
The publication has been published in Polish.
This thesis proposes and experimentally verifies a low-frequency method for identification of modifications of structural mass and stiffness. The proposed method is based on a nonparametric model of the unmodified structure, which is constituted by a set of its experimentally recorded responses. Such a nonparametric approach avoids the troublesome and error-prone stage of parametric model updating, while it allows parametrically expressed structural modifications and loads to be modeled and identified.
The approach was formalized by means of the general methodology of the virtual distortion method. The main idea is to model parametric modifications with the equivalent pseudo load, whose effect on the structural response is modeled nonparametrically. Such a general idea was developed into two specific formulations in time domain and in Laplace domain, including the direct and inverse problems. The gradient and the Hessian of the objective function were expressed analytically, which allowed the inverse problem to be solved by means of classical, gradient-based optimization methods of the first and second order. The basic formulations were extended to include the case of identification of an inelastic impact.
In the experimental verification, a 70-element space cantilever truss was used in the tasks of identification of mass and stiffness modifications and of dynamic loads.
