JVE International
Not a member yet
1200 research outputs found
Sort by
A parametric study on the dynamic response of reciprocating compressor with a revolute clearance joints
Get PDFDue to the friction and manufacturing and assembly errors, the clearance of revolution joints is unavoidable. When the clearance value increases to a certain value, the influence of clearance on the performance of the equipment could not be ignored. In this paper, the contact collision model is used to describe the effect of clearance. The model of reciprocating compressor is simplified properly, and the influence of revolution joint clearance on the system is studied by contact impact function. The influence of parameters on the acceleration of piston is studied by changing the size, position of clearance and velocity of crankshaft. The Lyapunov exponent of crosshead acceleration under the condition of load and no load are compared, which lays the foundation for studying the vibration of reciprocating compressor caused by clearance
On the use of signal smoothness estimates and signal similarity in bearing fault detection
Get PDFThe concepts of signal smoothness and signal similarity are very common in digital signal processing. In this paper, both concepts have been explored in the ball bearing failure diagnostics, where the bearing fault, bearing inner race and outer race faults were analysed. It was found out that the signal smoothness and the signal similarity estimates might reduce computational tolerance in the vibro-acoustic signal analysis. On this basis, numerous experiments have been carried out to demonstrate usefulness of the above-mentioned estimates (as useful parameters of signal features) in the signal quality analysis
Research on mobile robot path planning based on improved artificial potential field
Get PDFArtificial potential field method is one of the commonly used path planning methods. This paper introduces the defects of U-shaped obstacle problem, narrow channel, Local minimum, GNRON. Repulsive force field reconstruction is used to reduce the U-shaped obstacles and to solve the problem that cannot pass narrow channel, using “change target point as the target line” to solve the local minimum problem, for GNRON we use “Reverse repulsion force field” to solve. The feasibility of the algorithm is proved by simulation and analysis
Improved numerical approximation of dry friction phenomena
Get PDFIn the numerical investigation of vibration problems with dry friction it is accepted to use some type of approximation to this phenomenon. Often linear variation of the force of friction in a region around zero velocity is assumed. In this paper trigonometric variation is proposed and comparison of numerical results is performed. From the presented results higher precision of this approximation is observed
Ultimate shear performance and friction sliding response of laminated elastomeric bridge bearings
Get PDFIn major earthquakes, friction sliding of common laminated elastomeric bearings limits the force transmitted from the superstructure to the substructure. Experiments were carried out to investigate the ultimate shear performance and the friction sliding response of laminated elastomeric bridge bearings. First, the hysteresis curve of the common laminated elastomeric bearings present narrow ribbon which meant the energy dissipation capacity induced by the shear deformation was weak. The ultimate shear deformation of the bearings could reach 300 % to 400 % of the elastomeric thickness. The damage of bearings was mainly focused on the rubber layer fracture. Second, the energy dissipation capacity of elastomeric bearings induced by the friction sliding was larger than the shear deformation, and was similar with the lead rubber bearing. Since the total displacement include both elastomer shear deformation and sliding components, the dissipated energy continuously increased with the increasing of the sliding distance. When the tests finished, the bearings were basic intact, only the rubber surface was worn down. Last, the bilinear elastic-plastic model is proposed to take as the theoretical model of the elastomeric bearing with friction sliding for the research and design of bridge in earthquake
Analysis of nonlinear suspension power harvest potential
Get PDFBecause the power consumption of a controlled suspension is huge, the power harvest potential of a nonlinear controlled suspension is analyzed. Instead of simplifying the suspension to a linear model or adopting some control strategies to solve the problem, this paper investigates the effect of the nonlinear characteristics on the power harvesting potential. A mathematic model is introduced to calculate the nonlinear vibration, and the amount of harvested power was obtained using the multi-scale method. A numerical validation is carried out at the end of this study. The results show that the investigated mechanical parameters affect both the vibration amplitude and the induced current, while the electric parameters only affect the induced current. The power harvesting potential of the nonlinear suspension is generally greater than the linear suspension because the frequency band of the actual pavement also contains bandwidth surrounding the body resonance point. The only exception occurs if the vehicle travels on a road with a particular profile, e.g. a sine curve. To optimize harvested power, it is better to consider the nonlinear characteristics rather than simplifying the suspension to a linear model
Propagation of rotational waves in a block geomedium
Get PDFOn the base of assumption that the rotational movements of the chain of the crust blocks and the corresponding rotational waves characterizing the redistribution of tectonic stresses are described by the sine-Gordon equation with dissipation, the dispersion properties of this equation are analyzed. It is shown that the dispersion is manifested in the low-frequency range at high values of the dissipation factor. The presence of anomalous dispersion has been revealed for all values of the dissipation factor. Influence of this factor on dispersion is investigated. Some features of propagation of a stationary shock wave in a geomedium are studied. It has been found that the shock wave front width is directly proportional to the nonlinear wave velocity and to the dissipation factor of the medium, but it is inversely proportional to the nonlinearity coefficient
Sequential fault detection for sealed deep groove ball bearings of in-wheel motor in variable operating conditions
Get PDFSealed deep groove ball bearings (SDGBBs) are employed to perform the relevant duties of in-wheel motor. However, the unique construction and complex operating environment of in-wheel motor may aggravate the occurrence of SDGBB faults. Therefore, this study presents a new intelligent diagnosis method for detecting SDGBB faults of in-wheel motor. The method is constructed on the basis of optimal composition of symptom parameters (SPOC) and support vector machines (SVMs). SPOC, as the objects of a follow-on process, is proposed to obtain from symptom parameters (SPs) of multi-direction. Moreover, the optimal hyper-plane of two states is automatically obtained using soft margin SVM and SPOC, and then using multi-SVMs, the system of intelligent diagnosis is built to detect many faults and identify fault types. The experiment results confirmed that the proposed method can excellently perform fault detection and fault-type identification for the SDGBB of in-wheel motor in variable operating conditions
The modal analysis of three-dimension gun barrel using isogeometric analysis and its application to optimization
Get PDFIn this paper, the Isogeometric Analysis (IGA) is applied to make the modal analysis for 3D gun barrel. The geometry of IGA is modeled by None-Uniform Rational B-Splines (NURBS) which is exact and smooth even at the coarsest mesh level. The first 9 natural frequencies were calculated respectively by IGA and traditional finite element method (ABAQUS), and compared with the test results. The maximum relative error between numerical value and experimental value is less than 3.6 % which verifies the feasibility of numerical model. Six different refinement schemes were analyzed to compare the computational accuracy and efficiency of IGA and ABAQUS. To achieve the credible results, the CPU time of ABAQUS is more than twice of IGA. On this basis, the IGA method is used for the structural shape optimization of gun barrel. The first natural frequency is increased by 6.96 % and the barrel mass is reduced by 4.9 %
Vibration characteristics and modal analysis of a grinding machine
Get PDFThe machine industry has undergone several developments in the past years, and reducing the cost and time required for machine designing is important. In this study, the vibration characteristics of a precision grinding machine were obtained through experimental modal analysis and finite element analysis. The experimental modal analysis employed single point excitation, and the equipment used to determine the frequency response of the grinding machine comprised a hammer, an accelerometer, and a spectrum analyzer. In addition, the resonance frequency, damping factor, and modal shape of the grinding machine were determined. The natural frequency, modal shape, and interface stiffness were determined through finite element analysis. Finally, the theoretical model and the experimental modal analysis models were compared, and get closer to the actual situation of a model to conduct several times analysis. Thus, this paper presents a reliable and convenient method to study the characteristics of machine tools; this method can reduce unnecessary costs and find structural weaknesses in machine designs for improvement