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Fault diagnosis method of gear based on lifting wavelet packet and combined optimization BP neural network
Get PDFAiming at the problem of weak signal signature recognition of gear faults, a gear fault diagnosis method based on lifting wavelet packet and combined optimization BP neural network is proposed. The initial non-sampling prediction and update operators are calculated by Lagrange interpolation subdivision based on the principle of lifting wavelet, and the adaptive redundancy lifting wavelet packet decomposition and reconstruction algorithm is constructed. The network parameters of the number of hidden layers and the quantity of nodes, initial weights and thresholds of BP neural network are optimized by genetic algorithm (GA). The Levenberg-Marquardt (LM) algorithm is used to improve the search space of the network. Through experimental analysis, the results show that the gear fault diagnosis method proposed in this paper not only has high diagnostic accuracy, but also increase efficiency
Experimental study of self-sustainable hybrid solar photovoltaic cleaning mechanism coupled with water distillation unit
Get PDFIn the present research work a novel self-sustainable hybrid solar photovoltaic cleaning mechanism coupled with water distillation unit has been proposed. The experiments were conducted on the PV (photovoltaic) modules at Bennett University, Greater Noida A-block terrace from 7th to 13th October, 2019. Post installation, the average efficiencies of the solar PV module system with and without cleaning were compared to obtain a hike by 1.34 %. The water used for cleaning was recycled using a single slope basin type solar still which indicated a working efficiency of 67.94 %. On an average the solar still yielded 5.3 Litres of pure water every day during the experiment with a TDS (total dissolved solids) level of 104 ppm
Vibration analysis of cantilever beam in time domain and frequency domain using Arduino platform
Get PDFIn this paper, analysis is made in the field of mechanical vibrations using Arduino and MATLAB code. Test was conducted on a cantilever beam to extract the first three natural frequencies. Two specimens made of Aluminium and Mild Steel were considered for the analysis. The frequencies were first determined using experimental setup utilizing Arduino and MATLAB, later verified with the help of two methods: (1) Traditional “strike method” using 8-channel FFT analyser with Data Acquisition System (2) Analytical solutions available in Robert D Blevins for idealized continuous beam model. The results obtained for both specimens through these methods were compared with Arduino MATLAB code and found to be in very good agreement. Hence, in this work an attempt is made with the use of Arduino to extract few frequencies for simple structures which is less expensive, fast and provides reasonably good results and can be a substitute for FFT analyser, which is very expensive and time consuming
Assessment of foot trajectories and ground reaction force in a trans-femoral amputee with Jaipur Knee and 3R20 knee joints
Get PDFIn developing countries like India, unilateral transfemoral amputees encounter with the challenge to select and evaluate the knee joint performance. This study aims to evaluate the response of knee joint on vertical ground reaction forces (vGRFs), walking speed, range of motion (ROM) of joints like hip, knee and ankle joints in first two weeks and enhanced response. Movements of different joints were recorded through VICON motion analysis system. Vertical ground reaction forces were captured through AMTI strain gauzed force plate. It has been observed that in two weeks normalized speed increases 0.41 to 0.49 with 3R20. Range of motion of joints was observed with interesting fact that in general with 3R20, joints angle their respective ROM were more than Jaipur Knee but in same cases in second half of gait cycle Jaipur Knee responded better than 3R20 knee joint
Simulation on metro railway induced vibration. Part I: effect of out-of-round wheels
Get PDFThis paper discussed the effect of out-of-round wheels on simulation of rail dynamic behavior in the frequency range for ground vibration and ground-borne noise. A train-track interaction model was built by software Simpack and Abaqus. The input roughness was measured from a worn wheel and was applied moving on perfect smooth rail surface in different train speeds. Simulation results indicated that out-of-round wheel would affect the calculation result that could not be neglected, as the affected frequency range would be lower enough to influence the ground vibration (1-80 Hz) and ground-borne noise (16-250 Hz)
PCA based health indicator for remaining useful life prediction of wind turbine gearbox
Get PDFFault prognosis of wind turbine gearbox has received considerable attention as it predicts the remaining useful life which further allows the scheduling of maintenance strategies. However, the studies related towards the RUL prediction of wind turbine gearbox are limited, because of the complexity of gearbox, acute changes in the operating conditions and non-linear nature of the acquired vibration signals. In this study, a health indicator is constructed in order to predict the remaining useful life of the wind turbine gearbox. Run to fail experiments are performed on a laboratory scaled wind turbine gearbox of overall gear ratio 1:100. Vibration signals are acquired and decomposed through continuous wavelet transform to obtain the wavelet coefficients. Various statistical features are computed from the wavelet coefficients which return form high-dimensional input feature set. Principal component analysis is performed to reduce the dimensionality and principal components (PCs) are computed from the input feature set. PC1 is considered as the health indicator and subjected to further smoothening by linear rectification technique. Exponential degradation model is fit to the considered health indicator and the model is able to predict the RUL of the gearbox with an error percentage of 2.73 %
Comparative study for modal analysis of circular plates with various cutouts and end conditions
Get PDFThe applicational use of structural members in engineering and technology may take the form of a circular plate, for such members it becomes important to predict the vibrational characteristics when operated closer to resonance phenomena. In addition to, the effect of the cutout in the circular plate has a significant effect on modal characteristics. The part of the research work entitled in this paper emphasizes on the modal analysis of a circular plate with clamped boundary condition determined by the characteristics equation and mode shapes of the plate using FEM. The effects of inclusion of cut-out on the vibrational characteristics are discussed. The subject of the analysis was a circular plate considered with certain modifications i.e. free circular plate without cutout clamped on the outer periphery, circular plate with cut-out clamped on the outer periphery, circular plate with cutout clamped on the outer and inner periphery. The methodology applied to conventional material based circular plate is extended to Glass epoxy circular plate with the same set of modifications. The values of natural frequencies for various cases are tabulated and corresponding mode shapes are illustrated
A study on the behavior of structures based on the rocking motion of rigid cores involving pre-compressed springs and viscous dampers
Get PDFTo create a partial rocking mode in a building structure during an earthquake, two or more rigid cores with joint connection to the foundation, and capable of moving in the two main directions of the building’s plan, can be used. A rigid core with a hinge connection to the foundation is essentially unstable. However, two rigid cores can be connected together by springs and dampers in certain floors to create a stable structure. At the same time, the structure shows a rocking behavior in which the building moves almost as a rigid body. In fact, the effects of all modes other than the fundamental one is almost eliminated. The use of yielding or friction dampers leads to permanent displacements in the structure in an earthquake. Therefore, in this study pre-compressed springs were employed, which do not create any permanent displacement. The pre-compressed springs were used to provide the structure with initial stiffness and prevent any displacement by small forces. Since an elastic spring does not have any damping, it was decided to control the structural displacements by viscous dampers in certain floors. Finally, the proposed structure underwent static and time-history analyses in plastic range, and the results suggested the desirable behavior of the proposed structure. In particular, there were no permanent displacements left in the structure after the earthquake
Automatic condition monitoring of electromechanical system based on MCSA, spectral kurtosis and SOM neural network
Get PDFCondition monitoring and fault diagnosis play the most important role in industrial applications. The gearbox system is an essential component of mechanical system in fault identification and classification domains. In this paper, we propose a new technique which is based on the Fast-Kurtogram method and Self Organizing Map (SOM) neural network to automatically diagnose two localized gear tooth faults: a pitting and a crack. These faults could have very different diagnostics; however, the existing diagnostic techniques only indicate the presence of local tooth faults without being able to differentiate between a pitting and a crack. With the aim to automatically diagnose these two faults, a dynamic model of an electromechanical system which is a simple stage gearbox with and without defect driven by a three phase induction machine is proposed, which makes it possible to simulate the effect of pitting and crack faults on the induction stator current signal. The simulated motor current signal is then analyzed by using a Fast-Kurtogram method. Self-organizing map (SOM) neural network is subsequently used to develop an automatic diagnostic system. This method is suitable for differentiating between a pitting and a crack fault
Experimental study on secondary bearing mechanism of weakly cemented broken rock mass
Get PDFIn order to study the secondary bearing mechanism of weakly cemented broken surrounding rock, the surface of granite, limestone and mudstone broken rock samples were poured by cement slurry, and the weakly cemented rock mass was formed by static pressure infiltration method, and then an uniaxial loading test was carried out. The results show that the weakly cemented broken rock mass has a certain bearing capacity, but the bearing capacity is low, and the dispersion is high. The secondary bearing capacity of weakly cemented rock mass is affected by factors such as broken rock strength, rock particle size and rock gradation. The larger the rock particle size and strength are, the higher the secondary bearing capacity of the weakly cemented rock mass is. The average bearing capacity of the mudstone weak cementation specimen is 18.77 kN, and the residual bearing capacity is 1.46 kN, and a dispersion coefficient is 0.34. The average bearing capacity of granite is 343.65 kN, and the residual carrying capacity is 25.81 kN, and a dispersion coefficient is 0.11. The average bearing capacity of limestone is 367.22 kN, and the residual carrying capacity is 22.78 kN, and a dispersion coefficient is 0.3. After a certain grading, the average residual secondary bearing capacity of the weakly cemented rock mass is obviously improved, and the dispersion coefficient of peak bearing capacity is reduced. The grading scheme 1 has an average peak carrying capacity of 330.06 kN, a residual carrying capacity of 34.56 kN, and a dispersion coefficient is 0.07. The averaging scheme 2 has an average peak carrying capacity of 297.8 kN, a residual carrying capacity of 29.86 kN, and a dispersion coefficient is 0.14. The cementation regeneration mechanism of the broken rock mass mainly includes the cement-bonding effect of the cement slurry inside and on the broken rock mass. Under the loaded condition, the internal load-bearing network of the broken rock mass is the main mechanism for the secondary load of the broken rock mass, and the stability of the force-chain network is affected by the constraint. After the loss of the confinement, the force chain network fails, and the residual secondary bearing mechanism of the weakly cemented broken rock mass is transformed into the friction between the broken rock masses in the residual core rock pillar