Topic
Modal testing
About: Modal testing is a research topic. Over the lifetime, 4047 publications have been published within this topic receiving 64772 citations.
Papers published on a yearly basis
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TL;DR: In this article, the vibration modes of a cyclic symmetric rotor are investigated and the authors conclude that the vibration mode will present vanishing inertia forces and moments as they vibrate.
Abstract: This paper is to study how the vibration modes of a cyclic symmetric rotor evolve when it is assembled to a flexible housing via multiple bearing supports. Prior to assembly, the vibration modes of the rotor are classified as "balanced modes" and "unbalanced modes. " Balanced modes are those modes whose natural frequencies and mode shapes remain unchanged after the rotor is assembled to the housing via bearings. Otherwise, the vibration modes are classified as unbalanced modes. By applying fundamental theorems of continuum mechanics, we conclude that balanced modes will present vanishing inertia forces and moments as they vibrate. Since each vibration mode of a cyclic symmetric rotor can be characterized in terms of a phase index (Chang and Wickert, "Response of Modulated Doublet Modes to Travelling Wave Excitation, " J. Sound Vib., 242, pp. 69-83; Chang and Wickert, 2002, "Measurement and Analysis of Modulated Doublet Mode Response in Mock Bladed Disks, " J. Sound Vib., 250, pp. 379-400; Kim and Shen, 2009, "Ground-Based Vibration Response of a Spinning Cyclic Symmetric Rotor With Gyroscopic and Centrifugal Softening Effects, " ASME J. Vibr. Acoust. (in press)), the criterion of vanishing inertia forces and moments implies that the phase index by itself can uniquely determine whether or not a vibration mode is a balanced mode as follows. Let N be the order of cyclic symmetry of the rotor and n be the phase index of a vibration mode. Vanishing inertia forces and moments indicate that a vibration Mode will be a balanced Mode if n ≠ 1, N -1, N. When n = N, the vibration Mode will be balanced if its leading Fourier coefficient vanishes. To validate the mathematical predictions, modal testing was conducted on a disk with four pairs of brackets mounted on an air-bearing spindle and a fluid-dynamic bearing spindle at various spin speeds. Measured Campbell diagrams agree well with the theoretical predictions.
15 citations
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TL;DR: The present paper evaluates various modal testing methods based on the results of tests performed on a complex, realistic spacecraft structural system and concludes that the selection of a modalTesting method should be determined by the test requirement, constraints, and nature of the test article.
Abstract: Modal testing methods have undergone great changes in recent years as new testing methods are being created. Although devoted advocates of each method can be found to argue the relative advantages and disadvantages, the general superiority, if any, of one or the other is not yet evident. The present paper evaluates various modal testing methods based on the results of tests performed on a complex, realistic spacecraft structural system. It concludes that the selection of a modal testing method should be determined by the test requirement, constraints, and nature of the test article.
15 citations
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01 Feb 2011TL;DR: In this article, the authors explored and investigated the dynamic characteristics of car chassis structure by using experimental modal analysis (EMA) method and modal testing, which is divided into three parameters include natural frequency, damping factor and mode shape.
Abstract: This paper explores and investigates the dynamic characteristics of car chassis structure by using experimental modal analysis (EMA) method and modal testing. Dynamic characteristics are divided into three parameters include natural frequency, damping factor and mode shape. In this study, modal testing was performed on the car chassis including the impact hammer and shaker test. Data analyzer was used to convert the response signal from the sensor, which was in the time domain to frequency domain. Result obtained from both methods, is compared on each axis (X, Y and Z axis). However, small discrepancy was observed in terms of natural frequency, which is within the range of 5%. Based on the results, interpretation and comparison were made for both methods.
15 citations
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TL;DR: In this paper, the resonant frequencies and quality factors of a series of long, small diameter cylindrical pipes are measured and the dependence of the modal densities, calculated from these measurements, on pipe length, wall thickness and pipe material is in close agreement with theoretical statistical predictions.
15 citations
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TL;DR: In this paper, a parametric identification of multiple-input-multiple-output (MIMO) rotor bearing systems in the frequency domain on the basis of the maximum likelihood estimator (MLE) is presented.
15 citations