A multi-view optical technique to obtain mode shapes of structures

Patil, Kiran Kumari; Srivastava, Vanshaj; Baqersad, Javad

doi:10.1016/j.measurement.2018.02.059

Cited by 49 publications

(26 citation statements)

References 34 publications

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“…All the collected video-based registrations were in fact used to derive further feedback on MEMS estimations, from the post-processed digital images, as well as to assess the reliability of simple video-tracking techniques for dynamic identification and diagnostic purposes (i.e., [37][38][39][40], etc.). For engineering applications, the use of advanced video-based and digital image correlation techniques attracts the continuous attention of several research studies, both for remote-control and diagnostic investigations as well as dynamic identification purposes, and various promising contributions are available in the literature, even for large-scale and complex structures ( [41][42][43][44][45], etc. ).…”

Section: Vibration Test Results and Comparisonsmentioning

confidence: 99%

Vibration Analysis and Dynamic Characterization of Structural Glass Elements with Different Restraints Based on Operational Modal Analysis

2019

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Given a series of intrinsic features of structural glass systems (i.e., material properties, type of restraints, operational conditions, etc.), special care should be spent at the design stage, to ensure appropriate fail-safe requirements, but also in the service life of these innovative building components and assemblies. In this paper, the dynamic characterization of simple monolithic glass elements is presented, based on non-destructive laboratory experiments and Operational Modal Analysis (OMA) techniques, including Finite Element (FE) numerical simulations, classical analytical models, and video-tracking approaches. It is shown, in particular, how the actual restraint condition (i.e., flexibility of supports, with respect to ideal boundaries) can affect the vibration parameters of a given glass member (frequency and damping capacity). This turns out in possible variations of its overall structural performance, including stress-strain-related effects, hence suggesting the need for even further dedicated studies and methods for the reliable analysis and design of structural glass assemblies and complex systems under dynamic loads.

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Section: Vibration Test Results and Comparisonsmentioning

confidence: 99%

Vibration Analysis and Dynamic Characterization of Structural Glass Elements with Different Restraints Based on Operational Modal Analysis

2019

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“…With the advances in optical techniques, researchers have started to use digital image correlation (DIC) and photogrammetry for structural health monitoring 20 and nonintrusive vibration measurements 21 for mechanical components. [22][23][24][25][26][27][28][29][30][31][32][33][34] The optical techniques have also been used for full-field deformations in the biomechanical field. 35,36 Evans and Holt 14 used an optical technique to study mechanical properties of human skin and validate finite element results.…”

Section: Introductionmentioning

confidence: 99%

Vibration analysis of healthy skin: toward a noninvasive skin diagnosis methodology

et al. 2019

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Vibration analysis of healthy skin: toward a noninvasive skin diagnosis methodology,"Abstract. Several noninvasive imaging techniques have been developed to monitor the health of skin and enhance the diagnosis of skin diseases. Among them, skin elastography is a popular technique used to measure the elasticity of the skin. A change in the elasticity of the skin can influence its natural frequencies and mode shapes. We propose a technique to use the resonant frequencies and mode shapes of the skin to monitor its health. Our study demonstrates how the resonant frequencies and mode shapes of skin can be obtained using numerical and experimental analysis. In our study, natural frequencies and mode shapes are obtained via two methods: (1) finite element analysis: an eigensolution is performed on a finite element model of normal skin, including stratum corneum, epidermis, dermis, and subcutaneous layers and (2) digital image correlation (DIC): several in-vivo measurements have been performed using DIC. The experimental results show a correlation between the DIC and FE results suggesting a noninvasive method to obtain vibration properties of the skin. This method can be further examined to be eventually used as a method to differentiate healthy skin from diseased skin. Prevention, early diagnosis, and treatment are critical in helping to reduce the incidence, morbidity, and mortality associated with skin cancer; thus, making the current study significant and important in the field of skin biomechanics. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…This was overcome separately by Poozesh et al [5] and Molina-Viedma et al [6] using phase-based motion magnification and results are reported in [7] for 3D operational deflection shapes in the range from 1500 Hz to 6710 Hz without the need for high levels of excitation. Poozesh et al [8] and Patil et al [9] developed methods for the stitching of DIC images of sub-areas of very large structures to obtain complete images of vibration modes. Javh et al [10] developed an efficient gradient-based optical flow method and reported displacement resolutions of less than a thousandth of a pixel.…”

Section: Introductionmentioning

confidence: 99%

Basis-updating for data compression of displacement maps from dynamic DIC measurements

Chang

Wang

Siebert

et al. 2019

Mechanical Systems and Signal Processing

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The extraction of useful information and removal of redundant noise from data has become a major research topic in recent years. Data compression is necessary for all kinds of analysis, and the demand for efficient compression techniques has gained much attention. Digital image correlation is a camera-based measuring system, which has been widely applied in strain analysis because of the convenience of measuring displacement fields by simply selecting a region of interest. Currently, there is interest in applying such methods to engineering structures in dynamics. However, one of the major issues related to the integration of camera-based systems with dynamic measurement is the generation of huge amounts of data, typically extending to many thousands of data points, because of the requirements of high sampling rate, spatial resolution, and long duration of recording. In this paper a new algorithm is presented that addresses the need for efficiency in full-field data processing. By making use of the data itself and combining the concept of sparse representation with Gram-Schmidt orthogonalisation, the number of basis function used to represent the data can be reduced and a concise decomposition established. In both simulated and experimental cases, the compression ratios for data size and number of signals used in operational modal analysis are substantially diminished, thereby demonstrating the effectiveness of the proposed algorithm. A reduced number of new basis functions is determined for the representation of data under the condition that the reconstructed displacement map reproduces the raw measured data to within a chosen threshold on the coefficient of correlation.

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A multi-view optical technique to obtain mode shapes of structures

Cited by 49 publications

References 34 publications

Vibration Analysis and Dynamic Characterization of Structural Glass Elements with Different Restraints Based on Operational Modal Analysis

Vibration Analysis and Dynamic Characterization of Structural Glass Elements with Different Restraints Based on Operational Modal Analysis

Vibration analysis of healthy skin: toward a noninvasive skin diagnosis methodology

Basis-updating for data compression of displacement maps from dynamic DIC measurements

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