Dynamic substructuring with a sliding contact interface

In this paper, the general framework for dynamic substructuring is extended to time-variant interfaces among connecting substructures. Specifically, a time-variant interface due to a sliding contact is considered. The contact can be without or with friction. The problem can be tackled in time domain using primal assembly and numerical time integration, and in time-frequency domain using dual assembly, thus obtaining a Time Dependent Frequency Response Function (TD-FRF) of the assembled structure. The method is applied to lumped parameter models of substructures, and, under some assumptions, it can be extended to simple finite element models

Are rotational DoFs essential in substructure decoupling?

Substructure decoupling consists in the identification of the dynamic behavior of a structural subsystem, starting from the known dynamic behavior of both the coupled system and the remaining part of the structural system(residual subsystem). The degrees of freedom (DoFs) of the coupled system can be partitioned into internal DoFs (not belonging to the couplings) and coupling DoFs. In direct decoupling, a fictitious subsystem that is the negative of the residual subsystem is added to the coupled system, and appropriate compatibility and equilibrium conditions are enforced at interface DoFs. Compatibility and equilibrium can be required either at coupling DoFs only (standard interface), or at additional internal DoFs of the residual subsystem (extended interface), or at some coupling DoFs and/or some internal DoFs of the residual subsystem (mixed interface). Using a mixed interface, rotational coupling DoFs could be eliminated and substituted by internal translational DoFs. This would avoid difficult measurements of rotational FRFs. This possibility is verified in this paper using simulated experimental data

Experimental dynamic substructuring of the ampair wind turbine test bed

In a recent paper, the authors discussed the selection of a reduced set of interface DoFs in order to describe the coupling between the blades and the hub of the Ampair test bed wind turbine rotor. The study was conducted using simulated FRFs obtained from Finite Element model of the blades and the hub, but in view of using experimental FRFs. In this paper, test data measured on the turbine by the UW-Madison participants in the IMAC Focus Group on Experimental Dynamic Substructuring, and posted on the Wiki page of the group, are used for dynamic substructuring of the wind turbine test bed

30th IMAC, A Conference on Structural Dynamics

Topics on the Dynamics of Civil Structures, Volume 1, Proceedings of the 30th IMAC, A Conference and Exposition on Structural Dynamics, 2012, the first volume of six from the Conference, brings together 45 contributions to this important area of research and engineering. The collection presents early findings and case studies on fundamental and applied aspects of Structural Dynamics, including papers on: Human Induced Vibrations Bridge Dynamics Operational Modal Analysis Experimental Techniques and Modeling for Civil Structures System Identification for Civil Structures Method and Technologies for Bridge Monitoring Damage Detection for Civil Structures Structural Modeling Vibration Control Method and Approaches for Civil Structures Modal Testing of Civil Structures

Model reduction concepts and substructuring approaches for linear systems

In this chapter, we give an overview of some of the most common reduction techniques based on substructuring. Although all techniques follow a similar approach, the main difference between the methods lies into the basis vectors used in the approximation subspace to represent the dynamics of each substructure and the manner in which the substructures are a couple

DIC and Photogrammetry for Structural Dynamic Analysis and High-Speed Testing

This chapter provides an overview and some important considerations to be made when making optical and stereophotogrammetry measurements on structures for dynamic applications. In particular, the chapter focuses on leveraging those measurements to perform digital image correlation (DIC) to extract dynamic parameters (e.g., strain, deflection, operating shapes, and mode shapes). Structural dynamic testing and analysis in the context of performing optical measurements is described. Information on optical high rate testing is also presented along with lessons learned and best practices