Model Updating Using the Closed-Loop Natural Frequency

Jung, Hojin; Park, Youngjin

doi:10.2514/1.4179

Cited by 3 publications

(1 citation statement)

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“…The sensitivity-enhancing control (SEC) technique developed by Ray and Tian [23] uses a feedback control system in structures to improve the sensitivity of modal properties with respect to the change in the local stiffness or mass parameters. Similar approaches have been developed by Lew [24] using a virtual passive controller, and by Jung and Park [25]. Solbeck and Ray have investigated the feasibility of the SEC technique through damage detection experiments performed by adopting a coherence approach [26].…”

Section: Introductionmentioning

confidence: 94%

Modal Identification of Truss Structures by Changing Stiffness Using Piezoelectric Actuator

2008

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This study proposes a modal identification technique for truss structures by changing the stiffness using a piezoelectric actuator. The technique is formulated on the basis of the vibration characteristics of truss structures with a metal-sealed-type multilayer piezoelectric actuator installed in a specific truss member. The natural frequency of the truss is changed by the stiffness control of a truss member to identify the natural frequency of the truss structure; the axial stiffness of the truss member can be semi-actively controlled using piezoelectric materials and an electrical circuit. The frequency response amplitude is changed by the change of stiffness of the truss, then the change ratio of the frequency response amplitude can be used to identify the natural frequency of the truss, and then the excitation data are not required to be measured. The method is appropriate for the identification of space structures in orbit in the case when excitation data are not fully available because of unknown excitation forces and disturbances. Experimental demonstrations of the identification of the first bending modal frequency of a 10-bay truss with a piezoelectric actuator are presented. It is found that the estimated natural frequency is in good agreement with the exact frequency, even though excitation force data are not provided. Furthermore, the factors causing the identification error are discussed through theoretical sensitivity analyses. The results show that the identification error can be reduced when the frequency response amplitude of a specific excitation frequency derived from the natural frequency is used for the identification. Nomenclaturecapacitance matrix C p = capacitance of actuator c r = rth modal damping F i = excitation force f = external force vector f p = tensile force exerted on actuator H rij = frequency response amplitude for high stiffness H rij = frequency response amplitude for low stiffness K = stiffness matrix k p = constant-charge stiffness k r = rth modal stiffness M = mass matrix m r = rth modal mass for high stiffness m r = rth modal mass for low stiffness N = number of different excitation frequency n = number of degrees of freedom Q = electrical charge vector Q = electrical charge applied to actuator R j =Ĥ rij =H rij 1 R = 2 1 = 2 1 V p = voltage vector V p= voltagê X ij = stationary amplitude for high stiffness X ij = stationary amplitude for low stiffness x = displacement vector x p = displacement of actuator k = variation of modal stiffness k p = variation of stiffness of a piezoelectric actuator m = variation of modal mass @fg=@fg = partial derivativê r = rth damping ratio for high stiffness r = rth damping ratio for low stiffnesŝ r = rth mode shape for high stiffness r = rth mode shape for low stiffnesŝ r = rth natural frequency for high stiffness r = rth natural frequency for low stiffness ! = excitation frequency ! 1 = first resonance frequency for high stiffness ! 2 = first resonance frequency for low stiffness ! 1 , ! 2 = two extrema of R j Subscripts i = ith node of ...

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