Journal of Engineering and Thermal Sciences
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Rolling bearing health status assessment based on ITD-GMM method
Get PDFThis paper proposed a Rolling bearing health state assessment based on ITD-GMM method to fully dig the favorable information of the vibration signal from the rolling bearing with decline trend. By data analytic, the six components of vibration signal were calculated, and each component has three feature vectors. Finally, the performance of rolling bearing was quantified, and the curve of performance was acquired. The experimental results indicate that the method is feasible and effective for the assessment of rolling bearing
Torsional analysis of the engine computational model
Get PDFThe paper deals with basic behaviour and torsional analysis of the engine computational model. This computational model is assembled from own blocks which are created using the basic elements of Simulink software. The paper describes individual blocks and whole assembly of the engine computational model. The simulation of this diesel model was done to verify its function. In conclusion, torsional analysis was carried out
Research on dynamic characteristics of spiral basilar membrane after replacing artificial auditory ossicle based on the reconstructed human ear model
Get PDFIn this paper, PATRAN software was used to establish a complete 3D finite element model of human ears, and it was then combined with NASTRAN software to analyze frequency responses. This paper conducted a detailed analysis on the dynamic parameters including umbo and stapes displacements of normal human ears under sound pressures 90 dB and 105 dB. The numerically computational results were compared with experimental data. When the analyzed frequency was less than 1000 Hz, the computational result of numerical simulation was well consistent with the upper limit. When the analyzed frequency was more than 1000 Hz, the computational result of numerical simulation was well consistent with the lower limit. Therefore, the numerically computational model was reliable. In addition, based on the verified model, this paper studied vibration characteristics of spiral basilar membrane after replacing artificial auditory ossicle based on the whole hearing system, and found that vibration characteristics of spiral basilar membrane had an obvious change at low and high frequencies after replacing artificial auditory ossicle TORP. Using finite element method to analyze vibration characteristics of spiral basilar membrane can well predict the hearing recovery effect after replacing artificial auditory ossicle. Compared with normal ears, the vibration level of spiral basilar membrane after replacing artificial auditory ossicle has slowed down in 100 Hz-600 Hz, 2000 Hz-4000 Hz and 7000 Hz-10000 Hz, and has been strengthened in 600 Hz-2000 Hz and 4000 Hz-7000 Hz, which provided some help for the hearing recovery at the high-frequency band
Analytical modeling of a thin-walled cylindrical workpiece during the turning process. Stability analysis of a cutting process
Get PDFThe purpose of this work is to develop a mathematical model of the dynamics of turning a thin-walled cylindrical shell. This model uses a finite number of degrees of freedom and takes into account the variability of dynamic compliance. It is then possible to obtain estimates of the boundaries of stability of the continuous cutting process. The model is based on the theory of shells with application of Galerkin’s method in conjunction with the expansion of the displacement field in beam and trigonometric functions. On the basis of the developed model, an algorithm designed for constructing boundaries of stability of turning of the thin-walled cylindrical parts is presented and compared to experimental results. A strategy to define matter removal sequences is proposed
Simplified calculation method for transverse seismic response of aqueducts considering fluid-structure interaction
Get PDFAqueduct is the key structure in water conveyance engineering, which may be damaged during earthquake. Although numerous water conveyance designs have been built, the current state of researches on aqueduct aseismic design is inadequate. In this paper, based on the fluid-structure interaction dynamics and response spectra analysis, a simplified analysis method was proposed to evaluate the transverse seismic response of aqueducts, and the simplified calculating results were compared with the results of the nonlinear finite element calculation of fluid-structure interaction and experimental results. The results showed that the simplified analysis method put forward in this paper could be used to evaluate the transverse seismic response of aqueducts. In the condition that the pier height is less than 40 m, the first-order lateral vibration mode of the aqueduct has a higher model contribution rate; the simplified calculation method can achieve extremely high accuracy. The simplified calculation precision decreases as the height increases when the pier height exceeds 40 m
The net power control of hydraulic-electricity energy regenerative suspension
Get PDFFor achieving the control of hydraulic-electricity energy regenerative suspension (HERS), a novel control algorithm, net power control (NPC), is applied in this study. A HERS unit as a new energy reclaiming suspension device is equipped with an energy-harvesting hydraulic-electricity shock absorber (HESA). The composition and classification of HESA damping force were analyzed based on the basic working principle of HESA. Thus, the mathematical model of HESA damping force is deduced as a function of suspension dynamic speed and load current. A series of experiments were made to verify the reliability of the model. Based on the energy flow analysis of the suspension system, the net power flowing into the suspension is calculated. In order to minimize the vibration acceleration of the vehicle body, a novel net power control is proposed. The comparison result indicates the control effect of NPC is more significant than skyhook control, especially in the high excitation frequency. Also, the HERS bench test was carried out to verify the feasibility of NPC. The related results show that the maximum acceleration of the vibration is improved by 34.23 % with NPC on bump pavement excitation. And on B-class random road, the root mean square (RMS) value of the sprung mass vibration acceleration is reduced by 65 %. Furthermore, the influence of suspension dynamic velocity and deflection on the optimal control load current is obtained
Vibration dissipation of an axially traveling string with boundary damping
Get PDFAt present, the control of vibration problem of many engineering equipment can be simplified as a study on transverse vibration of axially traveling string system. In this paper, transverse vibration control and energy dissipation of axially traveling string system is investigated by using a boundary viscous damper. By analyzing the nature frequencies of the fixed length and the variable length of the string system, the resonance frequency of the external concentrated force is obtained. The amplitude and the energy reflection ratio of reflected wave to incident wave is investigated respectively by the force equilibrium principle and the energy equation at the boundary. According to amplitude and the energy reflection ratio, the range and the optimal value of damping coefficient are obtained. The effect of vibration dissipation with a viscous damper and an external concentrated force at the left boundary is investigated respectively by the numerical simulation
Analysis on shear lag effect of three-span continuous curve steel box-section girder
Get PDFAnalysis on shear lag effect of curved box-section girder use finite element analysis software, by change three-span continuous curve steel’s space geometry parameter into explore basic model, which study different central angel and different curvature radius influence take part act on three span continuous curve steel box-section girder. By analysis on shear lag effect of different central angel, we can draw a conclusion that the shear lag effect on inner side and outer side can appear a simultaneity. When inner side joint point approach plus max, in the same time the outer side joint point approach minus max. When curve box-section girder in earthquake effect, the inner side is much larger than outer side. When other factors are not change, the change of central angel influence a lot on shear lag effect. The central angel is smaller, the bigger shear lag on midspan’s inner side than outer side. When only change curve radius, the smaller curve radius is, the bigger on midspan’s outer side than inner side
Faulty bearing features by variational mode decomposition
Get PDFThis paper proposes a hybrid method based on Variational Mode Decomposition method (VDM) for detection of faulty bearing frequencies. The application of this method calls for a determination of the number of relevant frequencies K and a balancing parameter α; these are the key parameters of the VDM method. The operational modal analysis method and correlation coefficients are used respectively to estimate theses required parameters. The proposed method has been applied on experimental bearing signals at their early stages of degradation from 50 µm to 200 µm, as well as at an advanced stage of 2 mm. Results show a good identification of faulty bearing frequencies, which allows for the determination of the degradation severity
Design and finite element simulation of an ultrasonic transducer of two piezoelectric discs
Get PDFWith the developing of ultrasound technology and expending of it’s application scope, new requirements for the structure and the energy radiation of the transducer are presented. A reasonable design and manufacture of the transducer ensures that the energy can be transmitted with minimal loss. Based on the longitudinal vibration equation, a sandwich piezoelectric transducer which can be used in the field of precision machining, medical and other fields is designed and simulated in this paper. Different from the ordinary transducer, the front cover of this transducer is also a horn which can amplify the output amplitude compared to an equal section circular bar. ANSYS15.0 is used to calculate and analyze the transducer model with using HyperMesh (HM) software to generate the mesh to ensure the quality of the mesh. The finite element analysis software can calculate the transducer modal and harmonic response, and the results can be used to compare with theoretical design. The design frequency of the transducer is 20 kHz, the error between the simulation and the theoretical value is less than five percent, the result obtained by ANSYS is very close to the theoretical design