'Without doubt the best modern and up-to-date text on the topic, wirtten by one of the world leading experts in the field. Should be on the desk of any practitioner or researcher involved in the ...field of Machine Condition Monitoring'Simon Braun, Israel Institute of TechnologyExplaining complex ideas in an easy to understand way, Vibration-based Condition Monitoring provides a comprehensive survey of the application of vibration analysis to the condition monitoring of machines. Reflecting the natural progression of these systems by presenting the fundamental material and then moving onto detection, diagnosis and prognosis, Randall presents classic and state-of-the-art research results that cover vibration signals from rotating and reciprocating machines; basic signal processing techniques; fault detection; diagnostic techniques, and prognostics.Developed out of notes for a course in machine condition monitoring given by Robert Bond Randall over ten years at the University of New South Wales, Vibration-based Condition Monitoring: Industrial, Aerospace and Automotive Applications is essential reading for graduate and postgraduate students/ researchers in machine condition monitoring and diagnostics as well as condition monitoring practitioners and machine manufacturers who want to include a machine monitoring service with their product.Includes a number of exercises for each chapter, many based on Matlab, to illustrate basic points as well as to facilitate the use of the book as a textbook for courses in the topic.Accompanied by a website www.wiley.com/go/randall housing exercises along with data sets and implementation code in Matlab for some of the methods as well as other pedagogical aids.Authored by an internationally recognised authority in the area of condition monitoring.
In 1964, just a few years after the invention of the laser, a fluid velocity measurement based on the frequency shift of scattered light was made and the laser Doppler technique was born. This ...comprehensive review paper charts advances in the development and applications of laser Doppler vibrometry (LDV) since those first pioneering experiments. Consideration is first given to the challenges that continue to be posed by laser speckle. Scanning LDV is introduced and its significant influence in the field of experimental modal analysis described. Applications in structural health monitoring and MEMS serve to demonstrate LDV's applicability on structures of all sizes. Rotor vibrations and hearing are explored as examples of the classic applications. Applications in acoustics recognise the versatility of LDV as demonstrated by visualisation of sound fields. The paper concludes with thoughts on future developments, using examples of new multi-component and multi-channel instruments.
•A historical review of laser Doppler vibrometry (LDV) is presented.•Such a comprehensive review of LDV has not been authored before.•Single beam, parallel beam, multi-beam, scanning and tracking systems are considered.•Diverse applications are described e.g. modal analysis, structural health, MEMS, rotor vibration, hearing and acoustics.•The paper ends with thoughts on future developments.
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This paper describes a study on modal analysis and tension estimation of stay cables by vision‐based measurement under ambient condition. Microvibration of stay cable is captured by video ...camera, and the amplitude is amplified using phase‐based video motion magnification method. From the sequences of cable images, spatial displacements of the cable are extracted via discretized centroid searching method. Modal parameters of the cable, namely, natural frequency, damping ratio, and mode shape, are identified by dynamic mode decomposition method from cable displacement responses. Furthermore, tension of the stay cable is estimated based on the identified natural frequencies by minimizing an error function of an approximate relationship between frequency and tension iteratively. The technique is verified in the laboratory‐scale experiments and implemented to full‐scale measurement of medium size and long‐span cable‐stayed bridges. To compare the accuracy and efficacy of the vision‐based method, noncontact vibration measurement using laser Doppler vibrometer was also conducted. The results demonstrate that the proposed vision‐based vibration measurement techniques can estimate modal parameters and tension of the stay cables accurately in a noncontact and distant measurement under ambient condition. The proposed method offers an alternative of effective and accurate vibration measurement of stay cables using only motion of the cables recorded by video camera.
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This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal).
This article has been retracted at the ...request of the author due to errors in the test data. Since publication, errors have been found in the Z-vibration levels calculated from the research data. The author wishes to apologise for these inaccuracies.
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The cover image is based on the Research Article Railway sleeper vibration measurement by trainborne laser Doppler vibrometer and its speed‐dependent characteristics by Y. Zeng et al., ...https://doi.org/10.1111/mice.13150.
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A miniature fiber Bragg grating (FBG) vibration sensor with high performance and low angle dependence has been proposed and applied in the 2-D vibration measurement of a vibration isolation platform ...in this article. Considering the bonding points with maxim replacement, the sensitivity and resonant frequency theoretical model of the elastomer and packaged small-diameter FBG were established. The genetic algorithm was utilized to achieve the globally optimized structure sizes under multiple constraints, while the modal simulation analysis was carried out to verify the result. A novel "figure of merit" defined as the product of the resonant frequency, the sensitivity, and the inverse of package volume was proposed for the performance evaluation of the sensor in the unit space of its package. The 1st-order and 2nd-order frequencies of its <inline-formula> <tex-math notation="LaTeX">X-/Y </tex-math></inline-formula>-direction are 1105.4/1266.1 Hz, while the sensitivity is 127.861 and 116.668 pm/g, respectively. The cross-interference in the <inline-formula> <tex-math notation="LaTeX">X-/Y </tex-math></inline-formula>-directions of the sensor is less than 2%. Moreover, the test results of the angle dependence of the sensitivity show that the sensor possesses consistent sensitivity in all directions of the 2-D plane, while the fit sin functions in the <inline-formula> <tex-math notation="LaTeX">X-/Y </tex-math></inline-formula>-direction have a high <inline-formula> <tex-math notation="LaTeX">R^{2} </tex-math></inline-formula> of 0.99851 and 0.99831, respectively. Finally, the 2-D vector vibration measurement capacity of this sensor was demonstrated on a rubber spring vibration isolation platform. The results show that this miniature 2-D vibration sensor is suitable for medium-to-high frequencies vibration vector measurement and has a bright application prospect for the monitoring of machines.
Abstract The state of the art involving dynamic running actions is limited to single-person load models valid for running on a rigid laboratory floor. Little to no expertise is available on running ...excitation as a load scenario for civil engineering structures. The development of realistic load scenarios requires input on (1) intra-person variabilities, (2) inter-person variabilities and (3) human-structure interaction phenomena, and their impact on the resulting structural response. This contribution uses vibration measurements on the lower back of running persons to identify and characterize intra- and inter-person variabilities of the dynamic running load. Based on these results, the impact of these variabilities on the resulting structural response is investigated numerically. The results show that as the impact of intra-person variability is negligible, it can be disregarded in design calculations. However, the impact of inter-person variability is shown to be considerable, reducing the resulting structural response with 64% and more. Realistic ranges of inter-person variability should therefore be considered in design calculations.
Utilizing microwave continuous-wave Doppler radars to wirelessly detect mechanical vibrations have been attracting more and more interests in recent years. In this paper, aiming to solve the null ...point and nonlinear issues in small-angle approximation-based Doppler radar sensors and eliminate the codomain restriction in the arctangent demodulation approach, we propose and investigate an extended differentiate and cross-multiply (DACM) algorithm. With an additional accumulator, the noise performance of the original DACM algorithm is improved. Moreover, the amplitude information of the vibration can be directly retrieved from accumulation without involving any distance-dependent issue. Experimental validations show that the proposed algorithm can fully recover the vibration patterns with the measured noncalibrated amplitude agreeing well with the known precalibrated data. Application examples of mechanical fault detection and human vital sign detection are demonstrated, showing a wide range of potential applications of this algorithm.
Data are limited on the epidemiological implications of the recent change in terminology from nonalcoholic fatty liver disease (NAFLD) to metabolic dysfunction‐associated fatty liver disease (MAFLD). ...We therefore performed a cross‐sectional study of adults recruited in the 2017‐2018 National Health and Nutrition Examination Survey, a representative sample of the general US population. The prevalence of NAFLD and MAFLD based on controlled attenuation parameter (CAP) and liver stiffness measurement (LSM) obtained through vibration‐controlled transient elastography (VCTE) were 37.1% (95% CI 34.0‐40.4) and 39.1% (95% CI 36.3‐42.1), respectively, with higher rates among Hispanic individuals. Agreement between the two definitions was high (Cohen's κ 0.92). Patients with NAFLD and MAFLD also showed similar risk of advanced liver fibrosis (7.5% and 7.4% respectively). Our results suggest that the recent change in diagnostic criteria did not affect the prevalence of the condition in the general United States population.
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