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Modal testing

About: Modal testing is a research topic. Over the lifetime, 4047 publications have been published within this topic receiving 64772 citations.


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TL;DR: In this paper, an efficient non-destructive test method for measurement of effective elastic constants of orthotropic wood-based panels is proposed based on a modal testing technique, which is able to predict the frequency ranges and mode indices as well as corresponding normalized sensitivity to elastic constants based on initial estimates of Orthotropic ratios with uncertainties and measured fundamental natural frequency.
Abstract: Abstract Engineered wood-based panels are widely used in structural applications. Accurate measurement of their elastic properties is of great importance for predicting their mechanical behavior during structural design. In this study, an efficient non-destructive test method for measurement of effective elastic constants of orthotropic wood-based panels is proposed based on a modal testing technique. An algorithm was developed based on an improved approximate frequency equation of transverse vibration of orthotropic plates under the boundary condition, in which two opposite sides are simply supported and the other two are free (SFSF). The method is able to predict the frequency ranges and mode indices as well as corresponding normalized sensitivity to elastic constants based on initial estimates of orthotropic ratios with uncertainties and measured fundamental natural frequency. Full-size engineered wood-based panels including cross laminated timber (CLT), oriented strand board (OSB), and medium density fiberboard (MDF) were tested with the proposed method. In general, the measured elastic constants of the three types of panel based on modal test agreed well with those corresponding values measured by static tests. More tests are needed with a range of panel sizes and types for further validation of the proposed test method.

15 citations

Journal ArticleDOI
TL;DR: In this paper, an autoregressive model is applied for modal analysis of a flexible compact robot for grinding under impact conditions and then under operational excitations to characterize the manipulator's dynamic behavior in each direction.

14 citations

Journal ArticleDOI
TL;DR: In this article, the effect of fluid-structure interaction on the modal dynamic response of a water-surrounded slender bridge pier with pile foundation is studied. But the authors focus on the first four lateral modes of the pier.
Abstract: This paper presents an experimental program performed to study the effect of fluid-structure interaction on the modal dynamic response of water-surrounded slender bridge pier with pile foundation. A reduced scale slender bridge pier specimen is built and tested through forced vibration method. The vibration periods of the first four lateral modes, including the first two modes along -axis and the first two modes along -axis, are measured based on the specimen submerged by 16 levels of water and designated with 4 levels of tip mass. Three-dimensional (3D) finite-element models are established for the tested water-pier system and analyzed under various combined cases of water level and tip mass. Percentage increases of vibration periods with respect to dry vibration periods (i.e., vibration periods of the specimen without water) are determined as a function of water level and tip mass to evaluate the effect of fluid-structure interaction. The numerical results are successfully validated against the recorded test data. Based on the validated models, the modal hydrodynamic pressures are calculated to characterize the 3D distribution of hydrodynamic loads on the pier systems. The research provides a better illumination into the effect of fluid-structure interaction on the modal dynamic response of deepwater bridges.

14 citations

Journal ArticleDOI
TL;DR: In this article, the authors proposed a new piezoelectric shunt damping methodology to control the vibration of a computer hard disk drive (HDD) disk-spindle system.
Abstract: This work proposes a new piezoelectric shunt damping methodology to control the vibration of a computer hard disk drive (HDD) disk-spindle system. The first part of this work (part I) deals with dynamic modeling of the piezoelectric shunted drive, while the second part of this work (part II) covers experimental implementation of the proposed shunt circuits. In the modeling, a target vibration mode which significantly restricts the recording density increment of the drive is determined by analyzing the dynamic characteristics of the conventional drive. This is achieved by undertaking both modal testing and finite element (FE) analysis. In order to effectively suppress the unwanted vibration of the target mode, a piezoelectric bimorph is then designed and integrated to the drive by considering the mode shapes of the target vibration mode. The mechanical impedance of the shunted bimorph is derived from lamination theory and piezoelectric constitutive equations. In this derivation, the electromechanical coupling coefficient of the shunted drive is analytically incorporated with the mechanical impedance. Using the coupling coefficient, the shunt damping performance for the target vibration mode is predicted and evaluated by presenting the displacement transmissibility.

14 citations

Journal ArticleDOI
TL;DR: This study employs both the traditional and the complex modal analyses of a detailed finite element model of human head–neck system to determine modal responses in terms of resonant frequencies and mode shapes, and finds that a damping factor of above 0.2 has amplifying effect in reducing higher frequency modes, while a diminishing effect in lowering peak biomechanical responses.
Abstract: This study employs both the traditional and the complex modal analyses of a detailed finite element model of human head–neck system to determine modal responses in terms of resonant frequencies and mode shapes. It compares both modal responses without ignoring mode shapes, and these results are reasonably in agreement with the literature. Increasing displacement contour loops within the brain in higher frequency modes probably exhibits the shearing and twisting modes of the brain. Additional and rarely reported modal responses such as ‘mastication’ mode of the mandible and flipping mode of nasal lateral cartilages are identified. This suggests a need for detailed modelling to identify all the additional frequencies of each individual part. Moreover, it is found that a damping factor of above 0.2 has amplifying effect in reducing higher frequency modes, while a diminishing effect in lowering peak biomechanical responses, indicating the importance of identifying the appropriate optimised damping factor.

14 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202367
2022164
202141
202059
201967
201878