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Smart Structures and Systems
  Volume 13, Number 2, February 2014 , pages 219-233
DOI: https://doi.org/10.12989/sss.2014.13.2.219
 


Adaptive length SMA pendulum smart tuned mass damper performance in the presence of real time primary system stiffness change
Michael T. Contreras, Dharma Theja Reddy Pasala and Satish Nagarajaiah

 
Abstract
    In a companion paper, Pasala and Nagarajaiah analytically and experimentally validate the Adaptive Length Pendulum Smart Tuned Mass Damper (ALP-STMD) on a primary structure (2 story steel structure) whose frequencies are time invariant (Pasala and Nagarajaiah 2012). In this paper, the ALP-STMD effectiveness on a primary structure whose frequencies are time varying is studied experimentally. This study experimentally validates the ability of an ALP-STMD to adequately control a structural system in the presence of real time changes in primary stiffness that are detected by a real time observer based system identification. The experiments implement the newly developed Adaptive Length Pendulum Smart Tuned Mass Damper (ALP-STMD) which was first introduced and developed by Nagarajaiah (2009), Nagarajaiah and Pasala (2010) and Nagarajaiah et al. (2010). The ALP-STMD employs a mass pendulum of variable length which can be tuned in real time to the parameters of the system using sensor feedback. The tuning action is made possible by applying a current to a shape memory alloy wire changing the effective length that supports the damper mass assembly in real time. Once a stiffness change in the structural system is detected by an open loop observer, the ALP-STMD is re-tuned to the modified system parameters which successfully reduce the response of the primary system. Significant performance improvement is illustrated for the stiffness modified system, which undergoes the re-tuning adaptation, when compared to the stiffness modified system without adaptive re-tuning.
 
Key Words
    smart tuned mass damper; adaptive passive tuned mass damper; tuned vibration absorbers; shape memory alloy; adaptive length pendulum; observer based structural health monitoring
 
Address
Michael T. Contreras : Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
Dharma Theja Reddy Pasala: Department of Civil and Environmental Engineering, Rice University, Houston, TX 77005, USA
Satish Nagarajaiah: Department of Civil and Environmental Engineering and Mechanical Engineering and Material science,
Rice University, Houston, TX 77005, USA
 

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