Journal of Engineering and Thermal Sciences
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Acoustic emission localization on ship hull structures using a deep learning approach
Get PDFIn this paper, deep belief networks were used for localization of acoustic emission events on ship hull structures. In order to avoid complex and time consuming implementations, the proposed approach uses a simple feature extraction module, which significantly reduces the extremely high dimensionality of the raw signals/data. In simulation experiments, where a stiffened plate model was partially sunk into the water, the localization rate of acoustic emission events in a noise-free environment is greater than 94 %, using only a single sensor
Cognitive design of products for engineering and vibromechanics by criterion of minimization labor input of their manufacturing
Get PDFThe basis of the algorithm for determining the labor input are user-configured according to the parameters of its real production. It is shown that in the early stages of designing the designer can minimize the expected cost of the product by changing the design solutions, its head by a reporting engine will evaluate the range of materials and assortments and will issue guidelines to reduce it, and the technology and setters will calculate the final demand for materials and labor. Developed labor regulation system, built on the theory of fuzzy decision trees
Constructed solutions of face gear dynamics associated with engagement impact energy decay
Get PDFFace gear drives are focused by many researchers, due to several strong-points versus traditional spiral bevel gear drives. However, calculation solutions of face gear dynamics associated with engagement impact energy decay are not to be constructed, according to the limited published issues. Thus, in the study, a calculation solution of engagement impact energy decay of face gear drives is proposed, a face gear dynamic model is established, and the dynamic mesh forces of an example case of face gear drives without engagement impacts as well as with engagement impacts and engagement impact suppressions are simulated. The results indicate the fidelity of the proposed calculation solutions of face gear dynamics associated with engagement impact energy decay could be accepted. These contributions would improve the developments of face gear drive modifications and engineering applications of face gear drives in the future
Research on the vibration characteristics of the commercial-vehicle cabin based on experimental design and genetic algorithm
Get PDFMost of the published researches on the vibration isolation performance of the commercial vehicle focus on the suspension system and the power-train system, and few of them focus on the cabin. Moreover, the researches on the cabin mostly focus on how to reduce the interior noise, and the interior vibration characteristics have not received adequate attention. Therefore, this paper tries to research the vibration characteristics of the commercial-vehicle cabin in order to improve ride comfort. Firstly, the vibration characteristic of the cabin was tested on the actual road. Then, the rigid-flexible coupling dynamic model of the commercial vehicle was built, and the computational results were compared with the experimental results. It was found that the results were consistent with each other, which showed that the computational model was reliable. Finally, based on the verified computation model, some parameters that influenced the vibration characteristic of the cabin were explored. As a result, the influencing tendency of each parameter to the cabin vibration under each working condition was obtained, but influencing levels of each parameter cannot be analyzed quantitatively. In order to research the contribution degree of each parameter to the vibration in cabin, DOE (Design of Experiment) method was used for the analysis to provide references for the optimal matching of a cabin suspension system. Then, the vibration in the cabin was optimized based on genetic algorithm to obtain the optimal performance. This research can provide a reference for the other researches on the reduction vibration for the cabin
Influence of motor control characteristics on load sharing behavior of torque coupling gear set
Get PDFThe influence of the control characteristics of a direct torque control (DTC) motor on the load sharing behavior of a torque coupling gear set is studied by establishing a dynamic model of a multi-motor torque coupling system. The effects of run-out errors of the pinions of the torque coupling gear set on the powertrain are analyzed under steady operating conditions. The difference in rotational speed among the pinions becomes apparent, and the load sharing behavior deteriorates when there are run-out errors. The relationship between the control characteristics and load sharing behavior is studied. The difference in rotational speed decreases and the load sharing behavior improves as proportional and integral gains of the speed controller increase
Applied research of the multi-stage torsional vibration damper on controlling the gear rattle
Get PDFThe gear rattle noise of automobile transmission, which belongs to broadband noise, tends to attract the driver’s increasing attention. This paper performs a test on the noise, vibration and harshness (NVH) performance of power train in a passenger car. The results of the test show that the angular acceleration of the input shaft in the transmission increases with the increase of the angular acceleration of the flywheel, and excessive fluctuations of angular acceleration lead to the generation of the gear rattle in transmission. In this paper, a mathematic model of torsional vibration under the working conditions of acceleration, constant speed and deceleration has been established by taking a pair of helical gears as an example. The solving model of the mathematic model is set up by Matlab/Simulink and numerical solution has been solved. The theoretical analyses show that the ability of the traditional single-stage torsional vibration damper to attenuate fluctuations of angular acceleration is limited, while the multi-stage torsional vibration damper can attenuate larger fluctuations of angular acceleration, and the power train can provide good comfort and low fuel consumption. The experimental results in this paper are in accordance with above theories. Dynamic model of torsional direction of helical gears built in this paper is of great significance to the analysis of dynamic characteristics of gears. The multi-stage torsional vibration damper proposed in this paper can attenuate larger fluctuations of angular acceleration effectively, which plays an important role in controlling gear rattles, meanwhile it can enhance the riding comfort of a vehicle and reduce fuel consumption
The polynomial dimensional decomposition method in a class of dynamical system with uncertainty
Get PDFIn this paper, polynomial dimensional decomposition (PDD) method is applied to study the dynamical model for the first time. PDD method can reserve the amplitude-frequency characteristics of the exact solution which is obtained by the Monte Carlo simulation (MCS) method except the frequency close to the resonance, the perturbations appear around the resonance frequency. All these results are shown on the two degrees of freedom (DOF) spring system with uncertainties; the dynamical characteristics of stiffness and hybrid uncertainty uncertainty are studied in seven cases respectively. The higher PDD order approximates better to the MCS results
Effects of oil film properties on roller bearing with light loads under various slip factors
Get PDFIn this paper, ideal and general kinematics and models of roller bearing were built, and the oil film thickness for a roller bearing under a light load was analyzed with different slip factors. And then a new method to calculate the oil film thickness by considering a double slip ratio was developed, and the effects of different slip factors such as the slip ratio, inner ring speed, and radial load on the oil film thickness were investigated systematically. Under a zero slip ratio, the results showed that the film thickness increases with the inner ring speed. The radial load shows the reverse trend, and different slip factors affect the oil film properties differently. In the case with double slip ratio, the results showed that the film thickness slightly decreases as the roller slip ratio increases, whereas the cage slip ratio shows the reverse trend. The roller and cage slip ratios have different effects on the oil film thickness. The oil film distribution is affected by the combined action of the two slip ratios, the inner ring speed, and the radial load. The cage slip ratio can often be considered to be the main factor for calculating the oil film thickness
Stability enhancement method and experiment of orchard vehicle control
Get PDFStudy on orchard working vehicle rollover and tipping prediction is important to maintain vehicle stability control in complicated operation conditions of orchard. Existing rollover and tipping prediction models for vehicles can not directly apply to orchard working vehicle, which structure and loading are changing under operation. So it is necessary to move ahead study on orchard vehicle bodywork posture prediction and rollover and tipping prediction by theoretical analysis, mathematical modelling, real vehicle test and other methods. In this paper, firstly, we establish orchard working vehicle dynamic model, analyses variation of key parameters during vehicle instability state, and look for characteristic parameters of vehicle instability. Secondly, active safety control algorithm which based on posture detection of vehicle body is researched. Finally, control model is verified and optimized by scaled test
Spare support model based on gamma degradation process
Get PDFSpare parts ordering is very important in the domain of system support based on condition-based maintenance. For a single-unit system with condition monitoring, a joint degradation and spare parts ordering model is established in this paper to achieve the lowest total cost rate as the objective. The degradation process of system is assumed to be followed a gamma process. A decision on optimal spare ordering time by the improved cost rate model based on the proposed degradation model is made. Finally, a case analysis is implemented to demonstrate the effectiveness of the proposed model in this paper. Analysis results show that the proposed model can reduce the cost rate effectively