Experimental study and comparative analysis of pitting fault in spur gear system
By Kemajou Herbert Yakeu Happi, Bernard Xavier Tchomeni Kouejou, Alfayo Anyika Alugongo
This paper uses a dynamic six-degree-of-freedom model that considers torsional and lateral motions to predict the impact of pitting on vibration parameters in a spur gearbox for various operating speeds and torque loads. The study examines the dynamic characteristics of a gearbox with localized pitting damage on a single gear tooth using theoretical and experimental approaches. The research analyzes the forced vibrations of a single-stage spur gear system with pitting damage, which includes variations in mesh stiffness, damping, and gear error excitation, to identify symptoms of default. The equation of motion for the rotary gearbox system is established using the Lagrangian method in tandem with Short-Time Fourier Transform (STFT) and frequency-RPM map fault diagnosis. During real-time vibration monitoring, vibration signals are captured via accelerometers and processed in both the time and frequency domains using the LabVIEW data acquisition signal processing package to extract diagnostic information. The experimental findings demonstrate how vibration analysis combined with time-frequency processing can recognize machine conditions even in harsh operational conditions. Moreover, the experimental results indicate a significant similarity with the theoretical analysis and validate the effectiveness of the RPM frequency technique-based pitting detection method, which can be an asset in gear fault monitoring.
A simple harmonic quantum oscillator: fractionalization and solution
A quantum mechanical system that mimics the behavior of a classical harmonic oscillator in the quantum domain is called a simple harmonic quantum oscillator. The time-independent Schrödinger equation describes the quantum harmonic oscillator, and its eigenstates are quantized energy values that correspond to various energy levels. In this work, we first fractionalize the time-independent Schrödinger equation, and then we solve the generated problem with the use of the Adomian decomposition approach. It has been shown that fractional quantum harmonic oscillators can be handled effectively using the proposed approach, and their behavior can then be better understood. The effectiveness of the method is validated by a number of numerical comparisons.
Feedback force and velocity control of an arm exoskeleton to assist user motion
The paper proposes a feedback force and velocity control of an arm exoskeleton to assist user motion. The original published control so-called feedback hybrid force and position control was based on the force and position control and was designed to assist user motion. This original control was successful at providing assist for the user’s arm. This article presents an improved control scheme called the feedback force and velocity control. The proposed control is designed to regulate the velocities of joints of the exoskeleton and the feedback forces on links to assist user motion. The design and optimization of the feedback force and velocity control are realized by the Balancing Composite Motion Optimization (BCMO). The numerical method is realized in the paper to show that the proposed control is better than the original control in terms of less oscillation and fast response.
Optimizing mechanical properties of virgin and recycled PLA components using Anova and neural networks
The increasing demand for polymers in additive manufacturing (AM) has led to a significant increase in plastic waste, with over 300 million metric tons used in recent years. This research article explores the use of Poly Lactic Acid (PLA) as a biodegradable thermoplastic recycled material for 3D printed components, comparing its properties with virgin PLA and discussing solutions for variation and mechanical features improvement. Fused Deposition Modeling (FDM) is a widely used additive manufacturing process that allows for the creation of three-dimensional objects by depositing molten material layer by layer. This study investigates the impact of infill density, layer thickness, and raster angle for recycled 3D printing material, focusing on their dimensions and their influence on processing efficiency. This research paper aims to investigate the mechanical effects of recycled 3d printed components which are printed by using FDM with the combination of different process parameters compared with virgin PLA. From results optimal process parameters are found to enhancing quality and performance of recycled 3D printed components. Later results are compared by Analysis of Variance (ANOVA) as a statistical tool and also with ANN technique, which minimizes error deviation.
Improving piano music signal recognition through enhanced frequency domain analysis
Feature extraction is a crucial component in the analysis of piano music signals. This article introduced three methods for feature extraction based on frequency domain analysis, namely short-time Fourier transform (STFT), linear predictive cepstral coefficient (LPCC), and Mel-frequency cepstral coefficient (MFCC). An improvement was then made to the MFCC. The inverse MFCC (IMFCC) was combined with mid-frequency MFCC (MidMFCC). The Fisher criterion was used to select the 12-order parameters with the maximum Fisher ratio, which were combined into the F-MFCC feature for recognizing 88 single piano notes through a support vector machine. The results indicated that when compared with the STFT and LPCC, the MFCC exhibited superior performance in recognizing piano music signals, with an accuracy rate of 78.03 % and an F1 value of 85.92 %. Nevertheless, the proposed F-MFCC achieved a remarkable accuracy rate of 90.91 %, representing a substantial improvement by 12.88 % over the MFCC alone. These findings provide evidence for the effectiveness of the designed F-MFCC feature for piano music signal recognition as well as its potential application in practical music signal analysis.
Latest from engineering
Research on stress through photoelastic experiment and finite element method considering sliding wear
Sliding contact on the contact interface of friction pairs is a common type of contact. The sliding wear caused by sliding contact has an obvious influence on the stress in the contact area. In this study, the photoelastic experiment and finite element method are adopted to study variation laws of stress in the contact area. The results show that the stress in the contact region is very concentrated, and the contact half-width gradually ascends with the increase of sliding wear. The stress intensity in the contact region and von Mises stress at the contact centre decrease with the increase of wear depth. In the case of a wear depth of less than 0.3 mm, the stress intensity and the contact stress decrease rapidly with the growth of wear depth. When the wear depth exceeds 0.3 mm, the influence of wear depth on the stress intensity and contact stress is small. The results of this research clarify the effect of sliding wear on the stress in the contact area, and provide a reference for studying the contact issues.
Influence of sliding wear on contact characteristics based on 3-D wheel/rail contact model
During the process of starting, braking and running of the train, sliding contact between wheel and rail occurs. The wear caused by sliding contact exerts a noteworthy influence on the contact characteristics of wheel/rail. To analyze these characteristics, a three-dimensional wheel/rail contact wear model is established, and the contact characteristics at different wear depths are studied. The results indicate that at initial contact, the wheel/rail contact patch is approximately elliptical in shape and its area is 122.5 mm2. The von Mises stress of the wheel and rail is maximum in the subsurface at a distance of 2 mm from the contact interface, with maximum values of 559 MPa and 628 MPa respectively. When the wear depth is less than 0.5 mm, the wear depth, contact area and size increase quickly. As the amount of wheel contact wear increases, the maximum contact stress gradually decreases and the contact stress becomes uniform. In addition, the calculation results indicate that the contact patch shape does not always remain elliptical, the shape can change from elliptical to rectangular as the wear depth increases. As the increasing of wear amount, the contact stress gradient on the inner side of wheel contact surface increases.
Seismic reinforcement effect and vibration test of externally attached substructures in a selected Japan school building
In the long-term seismic work in Japan, an effective seismic reinforcement design system and reasonable seismic reinforcement technology have been developed, which is worth learning from. In this paper, the seismic reinforcement of a school building in Japan is taken as an example. Firstly, an overall reinforcement scheme of external prestressed precast concrete (PC) frame and steel brace is proposed. Then, based on the calculation results of seismic reinforcement and the ambient measurement before and after seismic reinforcement, the effectiveness and rationality of the seismic reinforcement method are analyzed. The results show that the seismic reinforcement method of attached substructures changes the original structural system, and solves the problems of excessive deformation and insufficient seismic performance. The reinforcement method improves the story stiffness of the structure, and the vibration period of simple harmonic motion after the implementation of seismic reinforcement is reduced by 0.845 times at most. The research results can provide reference for seismic reinforcement design and performance evaluation of existing school buildings.
Rolling bearing compound fault diagnosis based on spatiotemporal intrinsic mode decomposition
Aiming at the vibration signal characteristics of multi-channel rolling bearing complex faults containing various shock components, a rolling bearing complex fault diagnosis model based on spatiotemporal intrinsic mode decomposition (STIMD) method and fast spectral kurtosis method was proposed. The spatiotemporal intrinsic mode decomposition method combines the signal atomic decomposition method with the idea of signal blind source separation. Through the fast independent component analysis and the nonlinear matching pursuit method of the established overcomplete dictionary base, various fault mode components are separated. The initial phase function selected based on the high kurtosis fault frequency band obtained by the fast spectral kurtosis method can better fit the bearing fault frequency domain characteristics, so that the spatiotemporal intrinsic mode decomposition method can more accurately separate various impact components in the vibration signal. The simulation model of bearing compound fault was established and the data collected from fault diagnosis experiment platform were used to verify that the STIMD method was effective in solving the problem of rolling bearing compound fault diagnosis. By analyzing the kurtosis changes under different signal noise ratio (SNR) conditions and comparing the simulation results with the fast independent component analysis method, it shows that the kurtosis index decomposed by the proposed method is more able to prove the existence of faults under the condition of low SNR, that is, the impact is completely covered by noise. Therefore, a spatiotemporal intrinsic mode decomposition method with fast spectral kurtosis optimization can solve the problem of blind source separation in the field of composite faults of multi-channel rolling bearings and realize composite fault diagnosis.
January 21, 2024
Phase-shifted beamforming for denoising acoustic reflective signals
By Moli Chen
November 25, 2023
The effect of ambient temperature on the internal ballistic overload of a large-caliber artillery projectile fuze system
By Zilong Yang, Deren Kong, Chunyan Zhang
70th International Conference on VIBROENGINEERING
Advancements in Mechatronics: Integrating Vibrations, Robotics, Measurements and Mathematical Models
October 18-19, 2024
October 1, 2024
Best of engineering
November 27, 2023
Timber-to-timber composite floors connection optimization for vibration and deflection reduction
By Yuri De Santis, Francesca Pancella, Dag Pasquale Pasca, Angelo Aloisio, Massimo Fragiacomo
November 13, 2023
Concordance among three diagnostic methods for determining the position of the mandibular condyle
By Aidé Terán, Alejandro Liévano, Elia Núñez, Héctor Ruíz, Verónica Cabeza, Alejandro Lloret, Miguel Lloret
November 7, 2023
Experimental study on the rheological characteristics and viscosity-enhanced factors of super-viscous heavy oil
By Yang Chen, Jin Luo, Meiyu Zhang, Minglan He
October 8, 2023
Fault diagnosis of low-speed heavy load super large rolling bearing based on deep learning
By Simin Li, Hongchao Wang
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By Peter R. Michael, Danvers E. Johnston, Wilfrido Moreno
The standard for measuring solar irradiance utilizes the units of watts per meter squared (W/m2). Irradiance meters are both costly and limited in the ability to measure low irradiance values. With a lower cost and higher sensitivity in low light conditions, light meters measure luminous flux per unit area (illuminance) utilizing the units of lumens per meter squared or lux (lx). An effective conversion factor between W/m2 and lx would enable the use of light meters to evaluate photovoltaic performance under low solar irradiance conditions. A survey of the literature found no definitive and readily available “rule of thumb” conversion standard between solar irradiance and illuminance. Easy-to-find Internet sources contain conflicting and widely varying values ranging from 688449 to 21000 lx for 1000 W/m2 (1 Sun) of solar irradiance. Peer-reviewed literature contains Luminous Efficacy equivalent values ranging from 21 to 131 lx per W/m2. This manuscript explores the relationship and establishes a theoretical and laboratory measurement guide for the conversion between solar irradiance and illuminance. The conversion factor includes standards data, equipment calibration accuracy, and uncertainty estimates. Solar Irradiance of 1 Sun (1000 W/m2) for an LED-based solar simulator is (116 ± 3) klx and (122 ± 1) klx for outdoor sunlight.
Modal finite element analysis of PCBs and the role of material anisotropy
By Uday H. Kalyani, Mark Wylie
Printed Circuit Boards (PCBs) are epoxy resin-impregnated and cured sheets of counter woven glass fabric (e.g. FR4) laminated between thin sheets of Copper. The nature of the PCB is inherently anisotropic and inhomogeneous but previous modal FEMs of PCBs have assumed isotropic, anisotropic (transversely isotropic and orthotropic) material properties and shown good correlation with test data for specific scenarios [1-3]. This paper details part of a research program aimed at gaining a better understanding of accurately modeling PCB’s dynamic behavior. New investigations into the impact of material anisotropy and, in particular, the effect of material orthogonal plane definition (Ex and Ey) on eigenfrequencies is analysed. A modal FEM of a JEDEC PCB is created, verified, and validated using well established theories by Steinberg and empirical data by others [4, 5]. The relative contributions of Ex, Ey and Ez on PCB eigenfrequencies is examined using a parametric modal FEM, analysing the role of material isotropy verses anisotropy. The impact of transversely isotropic material properties is also analysed for a typical JEDEC PCB. This analysis details the mesh density required for accurately modeling the PCB eigenfrequencies. The results show that a 100 % increase in Ez has only a 0.2 % difference in the eigenfrequency where as a 100 % increase in Ey has a 1.2 % difference in the eigenfrequency. The effect of orthotropic plane definition (alternating Ex with Ey) on the JEDEC PCB amount to a 7.95 % delta in eigenfrequency.
Design and calculation of double arm suspension of a car
Suspension system is one of the challenging portions in designing a vehicle. The complete stability of the vehicle under dynamic conditions depends on the suspension system of the vehicle. Suspension system of a vehicle is interlinked with other systems such as steering, Wheels and Brakes. The main objective of this document is to provide complete guidance in designing and calculation of an independent suspension system with double control arms. The required parameters are calculated on considering a prototype vehicle with gross weight of 350 kg such as required stiffness of shock absorbers, Ride frequency, Motion ratio, Coefficient of damping etc. A CADD model was made with CATIA v5 r20 and SOLIDWORKS on the basis of calculations obtained and stress analysis was carried out for this model in various software such as Ansys. The complete assembled model was tested in LOTUS Shark and the result was obtained.
Coilgun design and evaluation without capacitor
Capacitors with high voltage and capacity values are used in most induction coilguns that are designed and constructed. The fact that capacitors are quite bulky and slow in energy transfer and how a coilgun can be made without using capacitors is the study subject of this article. Two and four coil gun samples were made to find the essential components of an electric gun, and the results are reported in this article. The accuracy of the results is also confirmed by FEMM analysis for these models. The harmony of experimental and theoretical results shows that smaller and low cost portable electrical weapons can be a powerful alternative to firearms in the future.