Mechanics

Asymmetric Helical Gears Bending Stress Calculation Formula

Xuezhong FU, Yuxin JIN, Malong ZHAO; Fa CAO — Sat, 08 Mar 2025 00:00:00 +0200

Aiming at the limitation that the traditional symmetrical gear stress calculation formula cannot be applied to the new asymmetric helical gear, a calculation method of tooth root bending stress of asymmetric involute helical gear are proposed in this paper. According to the meshing principle, the digital tooth surface model of asymmetric involute helical gear is established. The distribution characteristics of tooth root bending stress are analyzed by finite element method, and the relationship between tooth root bending stress and pressure angle is studied. On this basis, the influence coefficient of pressure angle is proposed. Combined with multiple regression analysis, an analytical formula for calculating the bending stress of tooth root without finite element method is proposed. By comparing with the calculated values of the finite element method, the error rate of the theoretical formula is 6.52%, which verifies its accuracy. The research results show that the asymmetric helical gear exhibits excellent tooth root bending bearing capacity under high pressure angle conditions, which provides key theoretical support and calculation tools for the design of high-performance asymmetric gears.

Many-Objective Production Scheduling Optimization Method for Aluminum Alloy Creep Forming Operation

Sang YANWEI, Ma YINGRU, Xu YAN, Zhu ZONGMING, Fang WENJUN, Peng YUBO — Sat, 08 Mar 2025 00:00:00 +0200

Due to the increasingly customized product requirements of customers, the production characteristics of the aluminum alloy creep forming components production line have changed to multiple varieties and small batches. As a result, it has the problems of complex production organization, low production efficiency. As far as we know, this is the first time to study the production scheduling problem of the aluminum alloy creep forming component production line. The whole-process production scheduling model is established. Multi-population coevolutionary optimization algorithm (MPCOA) is proposed. The MPCOA method uses three subpopulations for collaborative optimization. The sharing and integration of search information is realized through the interaction between subpopulations. For the optimization of the first subpopulation, an improved VAEA (vector angle-based evolutionary algorithm) which integrates the large neighborhood search is proposed. It can help to mine global information, and avoid local optimization. For the optimization of the second subpopulation, to get uniformly distributed solutions and improve the convergence, an improved decomposition-based method is proposed, which uses an improved Tchebycheff function and adaptive update weight vector mechanism. Computational experiments are performed by using industrial datasets and engineering production data. The competitiveness and superiority of the whole-process production scheduling model and the MPCOA method are demonstrated.

Development and Research of Technologies and Methods of Electro-flocking in the Decoration of Packaging Products

Olha SAVCHENKO , Edmundas KIBIRKŠTIS — Sat, 08 Mar 2025 00:00:00 +0200

The aim of this work is to analyze the modern electroflocking technology and to develop a new method for printing a color image on white flocked material. For packaging material, High Density Fiberboard (HDF) with a 3 mm thick white painted coating was chosen. Printing was carried out using DTI InkTec sublimation inks on an Epson L132 inkjet printer, followed by image transfer in an Amazon MAX 400C heat press. The image was applied to a 0.5 mm thick SEF FiberPlus thermal transfer sublimation flock film, which contains exclusive polyester microfibers and 100% polyurethane resins. Cutting of the packaging components was performed using a TS1390 CO₂ laser cutting machine with a wavelength of 10.6 µm. Image quality was evaluated using operational control scales. Microscopic photographs were taken at 60x magnification. Image fixation in the heat press was done using the following parameters: transfer temperature 170°C, transfer time 40 seconds, and pressure 3.0 bar. As shown by microscopic studies, the reason for the reduced optical density of the printed image with sublimation inks on flocked film is its high porosity. Therefore, to enhance the decorative effect and give the packaging an attractive velvety appearance, it is advisable to use a combination of printing on flocked material with cutting out several differently shaped and colored images from the flocked material.

Aerodynamic Shape Optimization of Simplified Ground Vehicle (Ahmed Body) using Passive Control Devices

Ahmet ŞUMNU, Yüksel ERASLAN — Sat, 08 Mar 2025 00:00:00 +0200

The present study aims to control the flow separation on the simplified ground vehicle (Ahmed Body) utilizing cylindrical roughness elements and vortex generators (VG) as passive control devices. To simulate the flow over the solid body, the Computational Fluid Dynamics (CFD) method was used and combined with aerodynamic shape optimization applied concurrently to obtain the optimal dimensions and position of the passive control devices. Firstly, aerodynamic analysis methodology was validated by conducting also mesh independence study with experimental results from the literature. Later on, by changing the slant surface angle of the model, the analyses were performed to indicate different scenarios and the results were presented visually for each case. Aerodynamic shape optimization is performed using a Genetic Algorithm (GA) on DesignXplorer in ANSYS to find the optimum size and location of the passive control devices that minimize drag force, as an objective. Consequently, the flow separation of the rear end of the body was found to be delayed or suppressed and vortex height is to be reduced thanks to the applied passive control devices. The total drag reduction was achieved by about 10.72%, and 13.37% for the optimal shape and location of the cylindrical roughness elements and VG devices, respectively, comparing to the baseline model.

Transient Simulation of Multi-Physical Field Coupling in Electrochemical Machining Microstructure

Xiang LI, Yuanlong CHEN, Yuanlong CHEN, Hua LIN — Sat, 08 Mar 2025 00:00:00 +0200

Microstructural electrochemical machining involves electric field, temperature field and gas-liquid two-phase flow field with complex coupling relationship. At present, there is no mature technology that can control processes such as ion exchange and liquid-phase mass transfer in the machining. Currently, there is no mature technology to control ion exchange and liquid phase mass transfer etc. in the machining. Therefore, in order to better understand the role of multi-field coupling and machining mechanism in microstructural electrochemical machining, a simulation study based on the multi-physics field coupling model is carried out to reveal the multi-physics field distribution law, which provides a guide for the subsequent research.

Mixed Elastohydrodynamic Lubrication in Micro Wedge-Platform Thrust Bearing Involving Adsorbed Layer

Xiaoying SHAO, Yongbin ZHANG — Sat, 08 Mar 2025 00:00:00 +0200

The film pressure and film thickness distributions, carried load and friction coefficient of the hydrodynamic lubricated micro wedge-platform thrust bearing were numerically calculated when the effects of the surface roughness, the surface elastic deformation and the physically adsorbed layer on the bearing surface were incorporated. The bearing clearance is so small that the effect of the adsorbed layer is significant but in the whole lubricated area there is the continuum fluid film. The flow in the bearing is multiscale and the solution is sought from the multiscale approach. The obtained results show that for the given load, sliding speed and surface roughness, the surface elastic deformation modifies both the film pressure and film thickness distributions, it makes the total lubricating film thickness increased but reduces the maximum film pressure; For the given minimum bearing clearance and sliding speed, the increase of the surface roughness increases both the film pressure and carried load of the bearing but the surface elastic deformation reduces this surface roughness effect especially when the fluid-bearing surface interaction is strong; The surface elastic deformation, the increase of the surface roughness and the increase of the interaction strength between the fluid and the bearing surface all result in the reduction of the friction coefficient of the bearing.

A Novel Fault Diagnosis Method for Acceleration Sensor Utilizing IEM-Based LLE and WKELM

Zihang GAO — Sat, 08 Mar 2025 00:00:00 +0200

In this study, fault diagnosis method for acceleration sensor utilizing information entropy measurement-based LLE and weighted kernel extreme learning machine (IEMLLE-WKELM) is proposed for fault diagnosis for acceleration sensor. First of all, this article proposes an information entropy measurement-based locally linear embedding (IEMLLE) algorithm to reduce the features of acceleration sensor data. The IEMLLE algorithm is a dimensionality reduction algorithm based on information entropy measurement. The discrimination of the distribution of sample data of the different classes based on IEMLLE is higher than that based on locally linear embedding (LLE) algorithm. Moreover, this article proposes a weighted kernel extreme learning machine (WKELM) algorithm, among which the use of kernel functions instead of hidden layer random feature maps containing activation functions is beneficial for improving the nonlinear processing ability and robustness of weighted extreme learning machine, and the chaos particle swarm optimization (CPSO) algorithm is proposed to optimize the penalty factor and the kernel parameter of weighted kernel extreme learning machine. The experimental results show that IEMLLE-WKELM is the higher fault diagnosis accuracy for acceleration sensor than LLE-WKELM, LLE-ELM, and principal component analysis-extreme learning machine (PCA-ELM).

The Improvement of Detection Precision of Internal Surface Detection System of Main Cylinder

Gui-long WANG, Bo YU — Sat, 08 Mar 2025 00:00:00 +0200

In view of the current status of the inspection of the main cylinder inner surface of the key components in the automobile brake system, an advanced inspection scheme integrating light, machine, electricity and calculation is put forward, the basic structure and the concrete implementation scheme of the detection system are given, and the geometric error elements are analyzed according to the working principle of the detection system, based on the theory of multi-body system and the principle of homogeneous coordinate transformation, the synthetic error model of the detection system is constructed, and the geometric error of the detection system is detected on-line by XL-80 dual-frequency laser interferometer, the existing geometric error data are obtained, the error compensation scheme of the detection system is put forward, and the error compensation verification of the detection system is carried out, it is proved that the proposed method can effectively improve the detection accuracy of the internal surface of the master cylinder.

Shape Optimization of the Aerostatic Bearing Considering Dynamic Performances

Yifei LI — Sat, 08 Mar 2025 00:00:00 +0200

The shape optimization is conducted to improve the dynamic performances of the aerostatic bearing with an air pocket. Firstly, the basic configuration of the air pocket used in the optimization is created, and four typical flow patterns are discussed. And then, the displacement impedance of the air film-floating facility system is studied, and the effects of bearing parameters on displacement impedance are discussed in detail. The approximate model of the displacement impedance is established; the optimization model is built based on the flow analysis, and both the Reynolds number and the maximum Mach number in the bearing clearance are considered in optimization to suppress the micro-vibration. The shape optimization is conducted and the optimum pocket configuration is achieved. Through optimization, the self-excited vibration is reduced, and the capability of the bearing to resist the external dynamic load is enhanced, which means that the operational stability of the aerostatic bearing is improved. The optimization process offers a reference for the bearing optimization in the engineering application.

Study on Simultaneous Identification of External Excitation and Response Reconstruction for Continuous System

Hongqiu LI, Jinhui JIANG, M Shadi MOHAMED — Sat, 08 Mar 2025 00:00:00 +0200

This paper proposes a novel dynamic response reconstruction method based on the Kalman filter which can simultaneously identifies external excitation and reconstructs dynamic responses at unmeasured positions. The weighted least squares method determines the load weighting matrix for excitation identification, while minimum variance unbiased estimation determines the Kalman filter gain. The excitation prediction Kalman filter is constructed through time, excitation, and measurement updates. Subsequently, the response at the target point is reconstructed using the state vector, observation matrix, and excitation influence matrix obtained through the excitation prediction Kalman filter algorithm. An algorithm for reconstructing responses in Continuous System using the excitation prediction Kalman filtering algorithm in modal space is derived. The proposed structural dynamic response reconstruction method evaluates response reconstruction and load identification performance under various load types and errors through simulation examples. Finally, a test system for structural dynamic response reconstruction on simply supported beams is constructed and tested. Results demonstrate accurate excitation identification under different load conditions and simultaneous reconstruction of target point responses, verifying the feasibility and reliability of the method.