Papers by Keyword: Random Vibration

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Authors: Yong Jie Zhang, Xiao Hu Zhang, Bin Tuan Wang
Abstract: The vibration data processing of environmental spectrum is an important part of environmental reliability test for the aircraft. Based on the inductive methods for environmental measured data of vibration, an inductive arithmetic is employed to estimate the random vibration data of aircraft surface in Matlab system. Numerical experiments show that the inductive estimation arithmetic is effective, reliable and applicable for the environmental measured data of random vibration.
Authors: Gang Liu, Si Zhong Chen, Hong Bin Ren
Abstract: Considering nonlinear characteristics of springiness and damping element, the quarter-car suspension nonlinear dynamic model is established with ADAMS. The simulation model of suspension established, and the simulation curve of nonlinear suspension is gotten by using the numerical simulation methods. The target parameters of the piecewise linear three stage control mode of the shock absorber are studied under the different random road excitation, it would provide the theoretical basic for the nonlinear damping matching of the vehicle suspension system.
Authors: Yong Xing Lu, Jia Hua Guo
Abstract: A new method based on bi-spectrum for generating random driving signal in time domain is presented for multi shakers in random vibration test. Firstly, the equivalent relationship of amplitudes and phases between auto-spectrum and bi-spectrum are established, Secondly, MIMO linear system are supposed, relations between driving bi-spectrum and response bi-spectrum are set up, inverse operation are used for calculating the driving bi-spectrum, Finally, the equivalent relationship are obtained, random driving signal in time domain according with reference requests are got. A numerical example is done, the result show existence of the equivalents. At the same time, random vibration experiment about cantilever beam is made to prove the effective aspects of the method.
Authors: M.A. Garcia-Romeu-Martinez, Vincent Rouillard, Michael A. Sek, V.A. Cloquell-Ballester
Abstract: During the transportation phase of the distribution cycle, packaging systems are subjected to random dynamic compressive loads that arise from vibrations generated by the vehicle. The level and severity of these dynamic compressive loads are generally a function of the vibration levels, the stack configuration and stack weight. The container’s ability to withstand these compressive loads for sufficiently long periods depends on the material’s characteristics as well as the container design. The research presented herein tests the hypothesis that cumulative damage in the material under random dynamic compression will result in a reduction in the overall stiffness as well as an increase in the overall damping of the element. These are expected to be manifested, respectively, as a shift in the fundamental resonant frequency as well as an increase in the bandwidth of the frequency response function of the material at resonance when configured as a single degree of freedom system. The paper presents the results of preliminary experiments in which a number of corrugated paperboard samples were subjected to dynamic compressive loads by means of broadband random base excitation with a vibration table coupled with a guided dead-weight arrangement. The level of cumulative damage in the sample was continuously evaluated by monitoring the stiffness and overall damping of the sample which were extracted from the Frequency Response Function (FRF) of the system. This was obtained from continuous acceleration measurements of the vibration table and the guided dead weight.
Authors: Douglas da Costa Ferreira, Fábio Roberto Chavarette, Cláudio Henrique Cerqueira Costa Basquerotto, Nelson José Peruzzi
Abstract: Common solution for energy harvester device is project design according harmonic excitation around natural frequency matching excitation source. Environment vibration is random and wide band causing short time of resonance in disagreement of project objectives. Control driven of energy harvesting to take advantage of the higher vibration range can results in greater energy converted. This study investigates a non-ideal excitation behavior and their efficiency in convert electricity via piezoelectric direct effect from the available system energy compared to harmonic excitation source. Numeric evaluation was performed based in bimorph piezoelectric beam in dimensionless consideration. Chaos behavior and harvest energy capability were compared from non-ideal to harmonic excitation. Results demonstrate considerable higher quantity of energy available for non-ideal approach compared to harmonic resonant design and encourages advance study to control and enhance energy from random and wide band vibration source.
Authors: Bo Huang, Xun Bo Li, Zhi Zeng, Xiang Li, Wen Hua Fang
Abstract: Random vibration is one of the main factors influencing the reliability of electrical connectors. In this paper, a Micro-USB electrical connector was chosen to be an object for this research. The finite element method was applied in random vibration analysis. At first, a three-dimensional model of the electrical connector was established by using Pro/E and ANSYS Workbench software. Then, the modal characteristics analysis was carried out and its modal parameters can be obtained from this analysis and the reliability of the electrical connector under the natural frequency can be also verified. Finally, according to results of the simulation, the equivalent stress and deformation response under 1 sigma levels hadn't changed much. The conclusions can provide a reference for the reliability analysis of electronic components.
Authors: Hai Wang, Xuan Zhou, Xiao Pin Xia
Abstract: Random vibration is being specified for acceptance tests, screening tests and qualification tests by manufacturers of electronic equipment meant for military applications, because it has been shown that random vibration more closely represents the true environment in which the electronic equipment must operate. In this paper, the simulation of the LCD panel subjected to random vibration load is done by the rectangle plate to represent the panel, the deformation and stress of LCD is analyzed by FEM method. Combined the simulation result and Taguchi optimization algorithm, we analyzed the relationship between the geometric dimensions of LCD and the dynamic response.
Authors: Heng Bin Zheng, Quan Sheng Yan, Jun Liang Hu, Zhou Chen
Abstract: For a space simply supported truss bridge model, a method named element modal strain energy (MSE) was firstly adopted in the field of the optimal sensors placement. By taking nodes MSE, nodes distance matrix reciprocal as weights, and combining with optimal matching in graph theory, how to apply the method for optimal sensors placement was stated. Through analyzing on the random vibration property of the bridge finite element model, the nodes position of larger acceleration response was compared with the optimal placement got from the above method, which could verified the effectiveness of optimal sensors placement.
Authors: You Tang Li, Chang Feng Yan, Wu Yin Jin
Abstract: The fatigue life of notched torus under random scan vibration is discussed in this paper. The stress function and stress field intensity of the materials under composted cyclic stress are analyzed. The experiments of vibration of the notched torus under random load are made in the digital vibration equipment. The fatigue life of notched torus is predicted by use the local stress-strain field method and three parameters formula. The elasto-plastic properties of the material are described by Von Mises yield criterion and stress-strain of uniaxial cyclic loading. The field of local fatigue damage of notched torus under random vibration is determined by using the method of local stress-strain field intensity, and the cycle stress-strain response near the tip of notch is obtained. The revised factor of fatigue life of LY12-CZ material is determined, the relationship between high-frequency cycle of stress and fatigue life is set up by use three parameters formula, and the fatigue life of the notched torus is obtained.
Authors: Zhen Qin, Wen Tao Xu
Abstract: In this paper, an efficacious and accurate method for analyzing random vibration and fatigue lifespan of coaches with high degrees of freedom is developed. Based on the design requirements for structure strength and fatigue lifespan of a coach, the finite element model of its body structure was used to investigate the dynamic behavior of the coach running on a randomly uneven road. The vibration characteristic was derived using the pseudo excitation method (PEM). The fatigue lifespan is discussed by means of the Miner rule, and the fatigue resistance is also studied. The reliability of the proposed method is numerically verified.
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