Offline eigenvector assignment for mass perturbation localization

Martin Dalgaard Ulriksen, Morten Eggert Nielsen

Publikation: Bidrag til bog/antologi/rapport/konference proceedingKonferenceabstrakt i proceedingForskningpeer review


The task of locating mass perturbations in structural systems has been explored extensively. Numerous methods address the task in a setting where perturbation-induced changes in some set of vibration features are mapped to the structural domain by aid of a model of the system in its reference/unperturbed state. One such method is the Shaped Damage Locating Input Distribution (SDLID) method, which operates by shaping inputs to suppress the steady-state vibrations in one structural subdomain at a time. When the subdomain containing the mass perturbation is rendered dormant, the perturbation effect will be nullified and the vibration response induced by the shaped inputs will be identical in the reference and perturbed states.

The SDLID method is hindered by the number of actuators required to deliver the inputs. This paper presents a further development of the SDLID method, which, under certain conditions, allows for limiting the required actuator count to one. The particular conditions are that multiple output sensors are employed, that the actuator is co-located with one of the output sensors, and that the input delivered by the actuator is measurable. Under these conditions, the input-output realizations can be processed offline to establish closed-loop systems, which can be designed through eigenstructure assignment to have a common node of mode (NoM) in multiple eigenvectors. When a common NoM is enforced in the perturbed location, the eigencharacteristics in the assigned modes will be identical in the reference and perturbed states, hence allowing for perturbation localization from inspections of, for example, the eigenfrequencies.

The applicability of the proposed method is examined in the context of simulations with a finite element model of a frame structure, which is analyzed in its reference state and in a perturbed state with an added point mass. The examination confirms that the offline eigenvector assignment allows for mass perturbation localization with just a single actuator.
Titel33rd Nordic Seminar on Computational Mechanics (NSCM)
StatusAfsendt - 2022