Optimal tuning of shunt parameters for lateral beam vibration attenuation with three collocated piezoelectric stack transducers

Structural vibration may occur in mechanical systems leading to fatigue, reduced durability or undesirable noise. In this context, shunting piezoelectric transducers to RL-shunts can be an appropriate measure for attenuating lateral beam vibrations. The achieved vibration attenuation significantly depends on an adequate tuning of the shunt to the structural resonance mode. In this paper, an existing method for resonant shunt circuit tuning based on electrical impedances is extended for lateral vibration attenuation of the first mechanical mode of a beam with circular cross-section and three collocated resonantly shunted stack transducers. It is shown by numerical simulation that a presented electrical impedance model including only the first beam mode can be used for the shunt parameter optimization if higher beam modes are taken into account

Anleitung zur Auswertung und Korrektur von verschrifteten Lotsenanweisungen sowie zur Ermittlung von Sracherkenner- und AMAN-Kennzahlen mit Hilfe des Tools „ControlAnnotation“

In der Abteilung Lotsenassistenz des Instituts für Flugführung des DLR wird im Rahmen des Projekts AcListant durch die Integration eines Spracherkenners zur Unterstützung des Arrival Managers (AMAN) angestrebt. Der Spracherkenner wird von der Universität des Saarlandes (UdS) entwickelt und in Kooperation mit dem DLR iterativ an die Bedingungen des Lotsensprechfunks angepasst. Für die Verbesserung des Spracherkenners werden Daten aus Simulationsläufen aufgenommen und in mehreren Arbeitsschritten mit verschiedenen, meist kommandozeilenbasierten Programmen verarbeitet. Zur Beschleunigung des Gesamtprozesses und zwecks Fehlerminimierung wurde das Tool „ControlAnnotation“ entwickelt. Dieses stellt eine grafische Benutzeroberfläche (GUI) bereit, über die nahezu alle am Prozess beteiligten Programme bedient werden können. Dieses Dokument dient als Bedienungsanleitung für ControlAnnotation

Effect of static axial loads on the lateral vibration attenuation of a beam with piezo-elastic supports

In this paper, vibration attenuation of a beam with circular cross-section by resonantly shunted piezo-elastic supports is experimentally investigated for varying axial tensile and compressive beam loads. The beam's first mode resonance frequency, the general electromechanical coupling coefficient and static transducer capacitance are analyzed for varying axial loads. All three parameter values are obtained from transducer impedance measurements on an experimental test setup. Varying axial beam loads manipulate the beam's lateral bending stiffness and, thus, lead to a detuning of the resonance frequencies. Furthermore, they affect the general electromechanical coupling coefficient of transducer and beam, an important modal quantity for shunt-damping, whereas the static transducer capacitance is nearly unaffected. Frequency transfer functions of the beam with one piezoe-elastic support either shunted to an RL-shunt or to an RL-shunt with negative capacitance, the RLC-shunt, are compared for varying axial loads. It is shown that the beam vibration attenuation with the RLC-shunt is less influenced by varying axial beam loads and, therefore, is more robust against detuning

Comparison of control strategies for global load path redistribution in a load-bearing structure

In this paper, a two mass oscillator, a translatoric moving mass connected to a rigid beam by a spring-damper system, is used to numerically investigate the capability of load path redistribution due to controlled semi-active guidance elements with friction brakes. The mathematical friction model will be derived by the LUGRE approach. The rigid beam is embedded on two supports and is initially aligned with evenly distributed loads in beam and supports by the same stiffness condition. With the semi-active auxiliary kinematic guidance elements it is possible to provide additional forces to relieve one of the beam’s supports. Two control strategies are designed and compared to induce additional forces in the auxiliary guidance elements to bypass portions of loading away from the spring-damper system towards the now kinetic auxiliary guidance elements. They depend on the different control inputs: I beam misalignment and II desired reaction force ratio in the supports. The beam’s misalignment and the supports’ reaction forces are calculated numerically for varying stiffness parameters of the supports and are compared with and without semi-active auxiliary kinematic guidance elements. The structure’s moving mass is loaded with a force according to a step-function. Thus, undesired misalignment caused by varying stiffness as well as undesired load distribution in the structure’s supports can be reduced by shifting load between the supports during operation

Effect of uncertain boundary conditions and uncertain axial loading on lateral vibration attenuation of a beam with shunted piezoelectric transducers

Undesired vibration may occur in lightweight structures due to excitation and low damping. For the purpose of vibration attenuation, resonantly shunted piezoelectric transducers can be an appropriate measure. In this paper, uncertainty in design and application of resonantly shunted piezoelectric patch transducers to attenuate the vibration of a beam due to uncertain rotational support stiffness and uncertain static axial loading is investigated. A linear mathematical model of a beam with piezoelectric patch transducers using RITZ formulation is used to calculate the vibration attenuation potential under uncertainty. Variation in the support stiffness and variation static axial loading lead to detuning and cause the resonant shunt to work off the desired frequency, resulting in higher vibration amplitudes. For a beam that is pinned or fixed at both ends, the attenuation effect is less sensitive to uncertainty in the support stiffness than in case of an elastic support that is neither fully pinned nor fully fixed at both ends. A beam fixed at both ends is most robust against uncertainty in static axial loading

Consistent approach to describe and evaluate uncertainty in vibration attenuation using resonant piezoelectric shunting and tuned mass dampers

Undesired vibration may occur in lightweight structures due to low damping and excitation. For the purpose of vibration attenuation, tuned mass dampers (TMD) can be an appropriate measure. A similar approach uses resonantly shunted piezoelectric transducers. However, uncertainty in design and application of resonantly shunted piezoelectric transducers and TMD can be caused by insufficient mathematical modeling, geometric and material deviations or deviations in the electrical and mechanical quantities. During operation, uncertainty may result in detuned attenuation systems and loss of attenuation performance. A consistent and general approach to display uncertainty in load carrying systems developed by the authors is applied to describe parametric uncertainty in vibration attenuation with resonantly shunted piezoelectric transducers and TMD. Mathematical models using Hamilton>'s principle and Ritz formulation are set up for a beam, clamped at both ends with resonantly shunted transducers and TMD to demonstrate the effectiveness of both attenuation systems and investigate the effects of parametric uncertainty. Furthermore, both approaches lead to additional masses, piezoelectric material for shunt damping and compensator mass of TMD, in the systems. It is shown that vibration attenuation with TMD is less sensitive to parametric uncertainty and achieves a higher performance using the same additional mass