Journal: Conference Proceedings of the Society for Experimental Mechanics Series

Abbreviation

CPSEMS

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Springer

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2191-5644
2191-5652

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2012 - 2019152020 - 202528
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Publications 1 - 10 of 43
  • Time-varying Spectral Submanifolds: Analytic Calculation of Backbone Curves and Forced Response
    Item type: Conference Paper
    Breunung, Thomas; Haller, George (2019)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Nonlinear Dynamics, Volume 1
    To understand and analyze the behavior of realistic nonlinear structures it is desirable to reduce the dimensionality of the system, as well as simplify the equation of motion. Reduction to Spectral submanifolds (SSMs) has recently been shown to provide such a dimension reduction, yielding exact and unique reduced-order models for nonlinear unforced mechanical vibrations. Here we extend these results to periodically or quasiperiodically forced mechanical systems, obtaining analytic expressions for forced responses and backbone curves on modal (i.e. two-dimensional) time-dependent SSMs. We demonstrate our analytical formulae on numerical examples and compare them to results obtained from alternative methods.
  • Nonlinear Structures & Systems, Volume 1
    Item type: Conference Proceedings
    (2023)
    Conference Proceedings of the Society for Experimental Mechanics Series
  • Rail Roughness Profile Identification from Vibration Data via Mixing of Reduced-Order Train Models and Bayesian Filtering
    Item type: Conference Paper
    Stoura, Charikleia D.; Tatsis, Konstantinos E.; Chatzi, Eleni (2024)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Model Validation and Uncertainty Quantification, Volume 3
    The increasing demand for mobility worldwide has led to an ever-increasing expansion of railway networks. Such a rapid expansion poses a challenge to guaranteeing quality, reliability, efficiency, and, most importantly, safety of railway infrastructure. Under this perspective, continuous monitoring emerges as a promising alternative to the traditionally adopted visual inspections, or inspections via portable measuring devices, which aim at collecting geometric data for the diagnosis and prognosis of defects in tracks. Recently, railway operators worldwide have adopted the use of dedicated Track Recording Vehicles equipped with optical and inertial sensors to collect data from tracks and assess their condition. Such an approach revolutionized rail condition assessment, introducing a mobile data acquisition platform for track inspection. On the other hand, the deployment of such specialized vehicles requires disruption of regular rail service, which hinders their frequent operation and thus the continuous collection of rail data. This work aims to tackle this limitation by examining an onboard monitoring (OBM) method that hinges on collecting vibration data from in-service trains. The proposed methodology relies on the collection of acceleration data from axle boxes of trains running at normal speeds. Its novelty lies in the usage of realistic train models and the consideration of the dynamic interaction between rails and trains, which is usually simplistically ignored. The adopted train models are reduced so as to decrease the required computational effort. The identification task is based on sequential Bayesian inference for joint input and state estimation, thereby also accounting for uncertainties related to the train model. Estimating the input leads to the identification of the pertinent rail roughness profile, which can subsequently provide information on the existence of isolated defects, for example, welded joints and squats, along the track system. This study is limited to reliable prediction of the dynamics of the train–track system in the vertical direction, but proposes methods and tools of general value.
  • Dispersion-corrected, operationally normalized stabilization diagrams for robust structural identification
    Item type: Conference Paper
    Dertimanis, Vasilis K.; Spiridonakos, Minas D.; Chatzi, Eleni (2015)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Model Validation and Uncertainty Quantification, Volume 3: Proceedings of the 33rd IMAC, A Conference and Exposition on Structural Dynamics, 2015
  • An examination of some aspects of factor analysis in damage detection
    Item type: Conference Paper
    Mozaffari, Salma; Bernal, Dionisio P. (2012)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Topics in Modal Analysis II
    It is well known that dynamic properties can be affected by environmental factors and this complicates the identification of damage. Among procedures explored to mitigate the fluctuations in dynamic features from environmental effects factor analysis is one of the simplest and has the merit that it operates without the need to measure the environmental variables. The method has been examined by several researchers in recent years but experience is limited and questions on some technical details remain open. This paper presents an investigation on three aspects that may affect the performance. The most important is the number of factors used in the analysis. The second relates to whether the diagonal nature on the covariance of random errors is enforced or not, and the third examines the influence of the criterion used to solve the over-determined set of equations that arise in the method. Results are obtained by simulating a system where the stiffness is cubically related to changes in temperature and where the temperature field, in each simulation, is a realization of a random process with a prescribed spatial correlation.
  • On-board monitoring of rail roughness via axle box accelerations of revenue trains with uncertain dynamics
    Item type: Conference Paper
    Dertimanis, Vasileios K.; Zimmermann, Manuel; Corman, Francesco; et al. (2020)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Model Validation and Uncertainty Quantification, Volume 3
  • Identification of Railway Bridge Modal Properties via Acceleration Data from Traversing Trains
    Item type: Conference Paper
    Stoura, Charikleia D.; Dertimanis, Vasilis K.; Chatzi, Eleni (2025)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Model Validation and Uncertainty Quantification, Vol. 3
    Bridges form a salient part of critical infrastructure networks that are faced with the adverse effects of aging. At the same time, the growing need for mobility has created new demands for higher traveling speeds and increased imposed loads, which introduce additional requirements on such aged structures. This motivates monitoring of the condition of bridges utilizing Structural Health Monitoring (SHM) schemes, which aim at identifying changes in the characteristics of the response of the respective structures. Such changes may signify the presence of damage or deterioration; thus, SHM is imperative for deciding on the remaining life of bridges and accordingly scheduling maintenance procedures. Focusing on railway bridges, SHM typically relies on stationary sensors mounted on the bridge system, with direct assessment of the collected data. Although reliable, such an approach hinders the comprehensive inspection of multiple bridges of a railway network, while the short life span of sensors poses limitations to the continuous supply of data from the structure. As an alternative, vibration-based mobile sensing that relies on traversing trains has the potential to provide data from multiple railway bridges based solely on a few sensor networks installed on the trains. At the same time, when running the network at frequent intervals (e.g., in the case of in-service trains), the sensor-equipped trains can also provide continuous data that give insight into the deterioration of bridges over time. To this end, this work proposes a model-based methodology to extract modal parameters of bridges based on acceleration data collected by traversing trains. The proposed approach relies on Kalman filtering for the estimation of the train’s state and input and a subspace identification method for the identification of the frequencies and modes of the bridge. Long-term monitoring of bridge frequencies and modes can contribute to the timely restoration in case of damage and, thus, ensure the safety and reliability of rail transportation.
  • Broadband electromechanical spectroscopy: A method for measuring the dynamic electromechanical response of ferroelectrics
    Item type: Conference Paper
    Wojnar, Charles S.; le Graverend, Jean-Briac; Kochmann, Dennis M. (2017)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Micro and Nanomechanics
  • Experimental Validation of the Dual Kalman Filter for Online and Real-Time State and Input Estimation
    Item type: Conference Paper
    Eftekhar Azam, Saeed; Chatzi, Eleni; Papadimitriou, Costas; et al. (2015)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Model Validation and Uncertainty Quantification, Volume 3: Proceedings of the 33rd IMAC, A Conference and Exposition on Structural Dynamics, 2015
  • Application of Geometrically Nonlinear Metamaterial Device for Structural Vibration Mitigation
    Item type: Conference Paper
    Chondrogiannis, Kyriakos Alexandros; Dertimanis, Vasilis; Chatzi, Eleni (2022)
    Conference Proceedings of the Society for Experimental Mechanics Series ~ Nonlinear Structures & Systems, Volume 1
    One of the major challenges encountered by civil structures throughout their life cycle pertains to exposure to dynamic loadings, with earthquakes representing an extreme case of such a load. The frequency content of a dynamic excitation is of primary importance not only because of the potential resonance it induces but also due to limitations that arise for the capabilities of vibration mitigation devices. A recently emerging technology for civil structure applications includes the development of metamaterial configurations. These are structures, which are formed by periodic arrangement of a fundamental component design, termed the unit cell. They can offer impressive filtering properties within specific frequency ranges, the so-called bandgaps. Considering the low-frequency content of earthquake excitation, a design that features a bandgap in the lower-frequency range is required. In this study, the potential of a geometrically nonlinear design for vibration mitigation purposes is investigated for lowering of the corresponding bandgap. The system consists in the periodic arrangement of nonlinear unit cells, each including a triangular arch configuration, which under large displacement considerations can produce not only geometrically nonlinear behavior but also negative stiffness effects. Analytical derivations result to the determination of the amplitude-dependent bandgap of the system. The proposed configuration is attached to a target structure subjected to protection. An assessment on the capabilities of the device toward this direction was performed via numerical analyses, revealing considerable effectiveness. Acceleration response and energy-related measures are considered in the evaluation of the system’s performance. An additional potential, which the proposed configuration can offer, refers to the applicability of the system for retrofitting purposes of existing structures. It is concluded that the system can offer significant vibration mitigation capabilities, while further study and development of the design, taking into consideration constructability limitations, can lead to an efficient passive vibration absorption device.
Publications 1 - 10 of 43