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Transient simulation of a hybrid test rig for broadband loading

 
: Jungblut, Timo; Atzrodt, Heiko; Drögemüller, Tobias; Herold, Sven

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Volltext ()

ResearchGate. Online resource (2009), 16 S.
Solid Mechanics Conference <7, 2009, Lisbon>
Englisch
Konferenzbeitrag, Elektronische Publikation
Fraunhofer LBF ()
transient simulation; hybrid test; broadband loading

Abstract
Today's test rigs for material and component testing are limited due to their working principle. Either they can only cover a small frequency range or, at higher frequencies, they can deal only with mono-frequent load signals at constant amplitude. Since this is an important restriction to the test process, current research projects are aiming on the extension of the test rigs' operating conditions. One interesting possibility is to integrate additional highly dynamic actuators in the conventional, mostly servo-hydraulic, load path. In this paper, a parameterized model for the simulation of the dynamic behavior of such a hybrid test rig is developed. Therefore, the mathematical models of the subsystems contributing to the dynamic behavior of the plant are derived. Rigid bodies and mechanical structures are represented by their mechanical admittance, whereas an impedance formulation is used to describe the dynamic stiffness of active or passive elements. This allows to interchange the submodels as well as to simulate different test assemblies easily. The submodels are validated with experimental data and assembled as an overall model for the plant. A sensor and control strategy for the hybrid test rig is developed in order to simulate the complete system comprising the plant and the signal processing subsystem. Therefore, not only the load in the test specimen is measured, but the force induced by the conventional actuators as well. The signal processing subsystem as a whole contains a model based linearization of the plant, an active damping of the first eigenfrequency and two independently designed SISO control loops for the low and high frequency actuators. The control law for the high frequency control loop as well as the gain required for the desired damping ratio are computed in model based way using a reduced LTI model of the plant. The simulation results of the overall system show the ability of the test rig as considered here in combination with the developed control system under certain conditions to track low and high frequency load signals at the same time.

: http://publica.fraunhofer.de/dokumente/N-487572.html