Journal of Vibroengineering
Not a member yet
3189 research outputs found
Sort by
An exhaustive research and analysis on seismic performance of prefabricated concrete shear wall structure
Get PDFIn order to accelerate the process of building industrialization, improve the overall stability and construction quality of the building. In this paper, a bolted connection method is designed to study the seismic performance of the composite concrete shear wall specimens with horizontal split joints from the aspects of bearing capacity, ductility, energy dissipation, deformation capacity and failure mode. The test results show that the bolted concrete shear wall is feasible and the connectors can effectively connect the upper and lower precast shear walls to form a whole with certain lateral stiffness. The energy dissipation capacity of the specimens is similar to that of other prefabricated concrete shear wall structures with “self-reduction”. The displacement Angle is greater than 1/120 of the limit value of the displacement Angle between elastic-plastic layers under the action of large earthquakes, and the specimen has good deformation capacity. The energy dissipation capacity of the structure from dynamics perspective reveals that smaller capacity of the specimen by providing energy dissipation factor E= 0.24 and equivalent viscous damping coefficient of 0.038
Synchronization of the secondary isolation system with a dual-motor excitation
Get PDFA dynamical model is proposed in this paper to study the synchronization and stability of the secondary isolation system with a dual-motor excitation. After deducing the dynamic equations of the system by Lagrange’s equation, the Laplace transform is used to deduce the displacement responses of the system when the system operate in steady state. The synchronous balance equation and stability condition of the system is derived with average method, and the relationship between the coefficient of synchronous ability and the geometric parameters of the system is discussed. It can be found that synchronization ability of the system is gradually increased with the increase between two motors mounting distance; meanwhile the larger difference of the mass between the two unbalanced rotors, the more difficult to implement synchronous operation of the system. Moreover, the stable phase difference of the vibrating system being as the key determinant to reach synchronization is discussed numerically. The research result shows that the synchronous behavior of the system is influenced by rotation direction of the rotors, mounting position of two motors, and mass ratios between unbalanced rotors and vibrating body. The correctness of theoretical analyses is verified by simulation results with Runge-Kutta method
Coupling characteristic analysis of ship shafting design parameters and research on multidisciplinary design optimization
Get PDFIn the design process of traditional ship shafting, the design quality is generally hard to get guaranteed for the lack of discipline coupling. In this paper, Multidisciplinary Design Optimization (MDO) is innovatively introduced to ensure design quality. Multidisciplinary decomposition of shafting can help to construct the MDO model of ship shafting based on multidisciplinary feasibility method. Then the sub-discipline model of shifting design can be further established, including calibration neutron discipline model, whirling vibration model, and dynamic stiffness of radial oil film bearing model. Collaborative operation is implemented by the multidisciplinary model of shifting to obtain the experimental results. Based on Radial Basis Function (RBF) neural network, the responsive surfaces of variable, bearing load, and support stiffness can be constructed, in the meanwhile the dynamic stiffness decoupling of vibration model can be obtained. Fireworks algorithm is used to establish multidisciplinary optimization of seven-dimensional design variable. The results show that MDO helps improve the quality of shafting alignment and whirling vibration. The work in present paper also provides insight for the future optimization of research methods, design quality, and engineering experiments
Optimal strain sensors placement to analyze the modal parameters of the sorting arm
Get PDFThe dynamics of light cantilever structure are complex under high-frequency reciprocating motion, and they cannot be obtained through simulation analysis. Therefore, it is necessary to use experimental analysis methods to study. At present, the main experimental method is to collect the vibration response of the sensors on the structure and then to analyze the dynamics. However, for light cantilever structure, the additional mass of the sensors changes the dynamics of the structure significantly, resulting in large errors in the results. The paper takes the sorting arm of LED chip sorting machine as the research object. An on-line identification of vibration experiment is carried out to obtain the dynamics of sorting arm with using of strain gauges, which avoided the error of the attached mass of the sensors. In addition, the result of experimental comparison verifies that using the strain gages can measure each mode of the arm structure more accurately. The method provides the guiding principle and basis for the dynamic optimization of the sorting arm mechanism
Mitigation of train-induced vibrations on nearby high-rise buildings by open or geofoam-filled trenches
Get PDFThe vibrations induced by moving trains especially in close distances with high-rise buildings can be destructive. The high technology of wilding rails induced a high train velocity which is associated with high vibrations. The buildings near the railways suffer from the train-induced vibrations. In this paper, a 3D FEM model was constructed to study the train-induced vibrations on a nearby high-rise building (HRB), show its response and investigate the most suitable technique to mitigate the effect of the train-induced vibrations by an open trench or a geofoam-filled trench. Three trench parameters were investigated to enhance the mitigation performance, the distance from the trench to the HRB, the trench depth and the use of either open (empty) trench or geofoam-filled trench. The geofoam-filled trench technique improved the dynamic response of the structure. Thus, trenches filled with geofoam can be considered a protection technique for high-rise buildings constructed near moving trains
Particle stratification of a vibrating screen with translation-swing composite motion
Get PDFWith the development of science and technology, more and more demand was proposed in the sieving industry. The sieving theory has been used to optimize parameters of vibrating screen to achieve a higher screening efficiency. Perfecting the sieving theory was became the main goal of most scholars to study the vibrating screen. Stratification as part of sieving theory research, the screening process and screening result was deeply influenced by stratification. In this paper, the sedimentation difference was defined to make the stratification became a numerical description. The discrete element method (DEM) has been used to simulate the screening process about the vibrating screen with translation-swing composite motion. The relationship between screening efficiency and sedimentation difference under each parameter is established and the effect of stratification on screening efficiency is studied under various single parameter conditions including vibration frequency, amplitude, vibration direction angle, swinging frequency, and swinging angle. The conclusions are: sedimentation difference is closely related to screening efficiency, the screening efficiency had obviously a positive correlation with the sedimentation difference. Combined with the value of the sedimentation difference, a better positive stratification is meaningful to the screening process and screening efficiency
The computational method of substructure’s frequency response function in transfer path analysis
Get PDFThe multi-degree-of-freedom coupled vibration system with “engine-mount-body” as the transfer path was divided into active substructure (engine), passive substructure (body) and linking components (mounts) between active and passive substructure. According to the dynamic equation of multi-degree-of-freedom coupling vibration system, the computational method of the substructure’s Frequency Response Function (FRF) was proposed. For the coupled vibration system of the real vehicle’s transfer path, the computational method of the substructure’s FRF was used to obtain the FRF of substructure and dynamic mount stiffness based on the FRF of system obtained by the hammering test. Combining the dynamic mount stiffness with the vibration acceleration of the active and passive sides of the mount, the operating load was identified based on the mount-stiffness method of the transfer path analysis. Combining the operating load with the FRF of substructure to analyze the contribution of the transfer path, the contribution of each path to the target location (the Z-direction of the front floor of the cab) was presented. The correctness of the computational method of the substructure’s FRF was presented by calculating the vibration isolation ratio of the mount, which provided theoretical support for the research of dynamic characteristics of the substructure and linking components
Early fault diagnosis method for gearbox based on second-order underdamped SR and its application
Get PDFStochastic resonance (SR) has been proved to be an effective method to extract weak-fault signals from gearboxes under strong noise. In this paper, we propose a method based on underdamped second-order SR with a new potential function. In our testing, we added an appropriate amount of Gaussian white noise to the original signal. When it matched the periodic signal and the potential function, the method showed good noise reduction ability, highlighted the fault signal and extracted fault information more effectively than the traditional SR method. The ant colony algorithm was used to optimize the potential parameters of the SR potential model and obtain the best output signal-to-noise ratio (SNR). We verified the proposed method by computer simulation and experimental verification, demonstrating that it produced better output than that of the traditional SR method
Vibration characteristics of Timoshenko stepped beam under moving load considering inertial effect
Get PDFThe vibration of gun barrels would result in the change of impact point, which would further reduce the firing accuracy of weapons. In the past, the calculation model based on the Euler beam theory could not satisfy the accuracy requirements. Based on the Timoshenko beam theory, the vibration equation of the stepped beam is established by invoking continuum transfer matrix method. The forced vibration of the stepped beam under the inertial moving load is solved. The model has better precision than the Euler beam model. The endpoint of the cantilever beam is analyzed. It is shown that the endpoint response increases with the increasing mass and acceleration of moving load, so does the inertial coefficient. With the increase of moving load speed, the endpoint response decreases, and the inertia coefficient increases. Among the three parameters, the mass of moving load is the main factor affecting the inertia coefficient. Furthermore, both free and forced vibrations of other stepped beam shaped structures with arbitrary segments and boundary conditions can be explored by using the proposed method
Dynamic reliability sensitivity analysis for inter-story isolation structure under stochastic excitations
Get PDFConsidering the uncertainties of seismic excitation and stochastic parameters of the Inter-story Isolation Structure, the implicit structural response function is transformed into an explicit one by the Stochastic Response Surface Method (SRSM), combined with a probabilistic collocation method based on the linear independence principle. By using the reliability analysis method based on the first-passage failure, the reliability of isolation structure is analyzed and the sensitivity of the reliability of each sub-structure is further analyzed. The results show that conducting sensitivity research based on reliability analysis can provide an important theoretical basis for an optimized and robust design of a random vibration system. The changes of the stiffness and damping ratio of the Isolation Layer have a great influence on the reliability of the system and have different effects on the reliability of different parts of the system. The analysis results of reliability sensitivity could provide system reliability indexes to rank stochastic parameters by their importance, thus improving the efficiency of the structure reliability analysis and optimization design