Advances in Mechanical Engineering

Wang, Jianlei; Lei, Longsheng; Li, Jianke; Liu, Chenyang; Jia, Qian; Fan, Xingyu; Cui, Yahui

doi: 10.1177/16878132241248154pmid: N/A

The function of the turbo-pump shaft within the liquid rocket engine is rendered exceedingly complex due to the operation in an environment characterized by drastically low temperatures, elevated velocities, and high pressures. Given these operational conditions, it is highly plausible that a two-phase flow might form within the liquid film located on the terminal face of the mechanical seal. This liquid-vapor mixture significantly modifies the fluid lubrication pattern across the end faces and poses consequential implications on the overall sealing stability. In this study, the phase change characteristics of the fluid in the seal clearance were investigated based on the Laminar and Mixture multi-phase flow models in a spiral groove mechanical seal. The behaviors of two-phase flow characteristics and phase transition under extreme temperature, rotational speed and pressure with liquid nitrogen media were studied. The sealing performance was quantified through metrics including the leakage rate, opening force, and internal gas phase volume ratio. The findings offered valuable insights into the role of operational conditions in influencing the phase change of the liquid film. Moreover, we discerned and explicated the intricate interconnections between the leakage rate, the opening force, and the phase change behavior of the liquid film.

Kaya, İsmail; Baykara, Cemal

doi: 10.1177/16878132241248072pmid: N/A

Efficiency is a concept that evaluates the optimal utilization of resources, including time, energy, finances, or materials, in order to accomplish a particular goal or objective. As widely acknowledged, energy losses occur in systems involving relative motion between interacting machine elements due to friction. In the case of a gearbox, these losses can arise from tooth friction in the gear mechanism, friction in sealing elements, friction in roller bearings, and the influence of the lubricant used in the system, all of which are subject to environmental conditions. This study aims to experimentally determine the efficiency of the gearbox under various operating conditions by considering the gearbox as a comprehensive system encompassing all its components. A measurement system was designed in order to obtain the efficiency of a gearbox. Experiments and measurements were carried out via software support. The measurement system contains two torque transducers, electrical resistive load device, an electrical motor with temperature measurement thermocouple, and two stage helical gearbox. In experiments conducted through computer commands, input revolutions were incrementally increased with 400 rpm intervals within the range of 700–2700 rpm. Moreover, experiments were carried out at different lubricant levels in the gearbox. At the same time lubricant temperature was measured and effects to the gearbox efficiency were investigated. Subsequently, different lubricant with distinct viscosity indices were employed. As a result of this experimental design, regime efficiency values were obtained for each case. Thus, power loss of the gearbox system has been determined. These results were examined using a general full factorial design. Analysis of variance (ANOVA) tables were created and the effects of the parameters on the system and the efficiency results were determined by checking whether the parameters were interacting or not. Finally, regression analysis was performed and the regression function was obtained in order to develop a predictive model to estimate the efficiency of a gearbox.

Li, Jie; Chen, Dantong; Si, Jiahui

doi: 10.1177/16878132241244889pmid: N/A

With the rapid growth of the new energy vehicle industry, the number of end-of-life power batteries, which serve as the technological core, is also increasing significantly. Unfortunately, this rise in retired power batteries has led to severe environmental pollution and resource wastage. The detection of shell bolts in power batteries has thus become a crucial step in the recycling and disassembly process. To address this issue, this research proposes a detection method for end-of-life power battery shell bolts. Based on market analysis, the target bolt for the retired power battery shell was identified. The bolt images were collected and preprocessed to create a custom dataset on the experimental platform. Four popular object detection algorithms were compared, and the YOLOv8 model is selected to improve with EMA module. The improved YOLOv8 model achieves 98.9% for mAP_0.5, which increases more than 2 percentage points. Based on the repeatability of bolt recognition, this detection method can be used for the identification of bolts in other battery shells, providing a theoretical foundation for promoting the robotic disassembly of battery shells.

Jiang, Fan; Li, Kai; Wu, Honghua; Luo, Shihui

doi: 10.1177/16878132241242953pmid: N/A

The 120-type air brake system is unique around global rail industry and critical for Chinese freight train operation. Existing research about its simulations does not include detailed models for the emergency brake valves. This paper filled this research gap by developing a detailed fluid dynamic air brake system with a focus on the emergency brake valve. The working principle of the emergency brake vale was reviewed. The brake system model was based on gas flow governing equations (mass and momentum) and orifice flow equations. The model was validated by comparing with measured data from a 150-wagon train. Four braking scenarios were compared. The simulated maximum cylinder pressure was only 5 kPa out of the range of the measured data. The maximum difference regarding the time when cylinder pressure reaches maximum pressure was 4 s. The simulation results have also shown variable switch pressure points for the two-stage brake valve. This is agreed by the measured results and was not shown in previously published research.

Nkrumah, Jacob Kwaku; Cai, Yingfeng; Jafaripournimchahi, Ammar

doi: 10.1177/16878132231220355pmid: N/A

The automotive headlight stands out as a critical vehicle component, particularly emphasized during nighttime driving. The high beam, designed for optimal driver visibility on long-distance roads, traditionally relies on manual control by the driver. However, this manual control poses challenges, particularly when the high beam light temporarily blinds oncoming drivers. The resultant dazzle for drivers of opposing vehicles is a significant concern. In response to these issues, there is a growing demand for adaptive and intelligent headlights that can autonomously adjust beam intensity. The intelligent headlight system takes on the responsibility of modifying the beam intensities without requiring explicit input from the drivers. This study aims to systematically review various approaches to controlling intelligent headlight beam intensity. The paper identifies four prominent approaches to intelligent headlight beam intensity control, recognized as widely used techniques. Furthermore, the study uncovers intriguing connections between some of these intensity control approaches. A survey on utilization rates indicates that sensor-based and machine learning (ML)-based intensity control approaches are the most commonly employed methods by automotive headlight designers. The paper concludes by providing insights into the future prospects of intelligent headlight technology, offering guidance for future researchers in this field.

Zhang, Hongyuan; Li, Shuo; Sun, Hongyun

doi: 10.1177/16878132241240928pmid: N/A

Time-varying meshing stiffness is one of the important excitations of gear transmission system, and its accurate calculation is an important basis for gear dynamics research. This paper proposes an improved potential energy method to calculate the theoretical time-varying meshing stiffness of healthy gears and helical gears with root crack faults, taking into account the non coincidence between the tooth root circle and the base circle of the helical gear, as well as the angle of the tooth root transition circle, the simulation results of KISSsoft were used to verify the rationality and effectiveness of the improved method; analyzed the influence of basic parameters and fault severity of helical gears on time-varying meshing stiffness. The results show that the accuracy of meshing stiffness obtained by the improved method has increased by about 5%; changes in the basic gear parameters cause changes in the contact ratio, which in turn leads to changes in the fluctuation and average value of the gear meshing stiffness; the fluctuation of meshing stiffness is in the minimum value when overlap contact ratio is close to an integer, the fluctuation of meshing stiffness is in the maximum value when total overlap is near an integer; the variation of crack depth and angle leads to local attenuation of time-varying meshing stiffness of helical gears. As the degree of failure increases, the local attenuation of meshing stiffness becomes more pronounce and compared to crack angle, meshing stiffness is more sensitive to changes in crack depth. Compared with the traditional potential energy method, the improved method improves the calculation accuracy of the time-varying meshing stiffness of helical gears, which is highly practical in the accurate calculation of helical gear meshing stiffness excitation and provide the theoretical basis for the calculation of the meshing stiffness of helical gears.

Zhang, Jiaqi; Xue, Bin; Liang, Jun; Guo, Yuanming; Li, Tiejun; Li, Detang; Xie, Yonghe; Wang, Jun; Hong, Yongqiang

doi: 10.1177/16878132241241428pmid: N/A

Marine sediments are important for research in scientific fields such as marine geology, environmental testing of waters, marine biology and seabed resource exploration. Among them, mud miner is an important way to obtain sediments. However, due to the complexity of the marine environment, the seabed sampling operation is a relatively difficult and complicated project. The structural design of the sampler, the operation mode, and the interaction between the sampler and the sediment affect the sampling effect, which leads to the low efficiency of the sampler operation. In order to investigate the main factors affecting the drag force of the sampler during seafloor sampling, this paper takes a simple and portable anchor-type mud collector surface sediment sampler as a study. This paper introduces the mechanical structure and working principle of an anchor-type mud collector, establishes a mechanical model of the mud collector seafloor sampling process and derives the main factors affecting the dragging force: internal friction angle; the horizontal angle of the bi-directional shaft rod; undercut angle β of bottom cover and dragging speed. A FEM-SPH method based on the coupling of the finite element method (FEM) and the smooth particle hydrodynamics method (SPH) was proposed to simulate the dynamic process of mud collector subsea sampling, and the mechanical data of fine sand and clay were obtained through land-based experiments. Based on the comparison between experimental data and numerical simulation data, the simulation validity of the FEM-SPH method was verified. The results show that the drag force of the clay was greater than that of the fine sand in the experiment of cutting the lower cover of the mud collector into the fine sand and clay, the internal friction angle of the clay is greater than that of the fine sand; with the increase in horizontal inclination angle and the decrease in undercut angle, the dragging force gradually increased; The dragging speed ranged from 0.2 to 0.6 m/s, with an increase in the mass of clay and fine sand collected with increasing speed, resulting in a gradual increase in dragging force. This paper provides a new method to study the force of the mud collector, provides a theoretical method to reduce the intensity and difficulty of manual work in the sampling process and increase the efficiency of sampling.

Pan, Like; Peng, Peihuo; Xing, Tong; Yang, Caizhi; He, Fan

doi: 10.1177/16878132241239799pmid: N/A

The increase of the running speed of electric train has a certain influence on the dynamic performance of coupling of conductor rail and collector shoe. In this paper, the mechanical characteristics of coupling vibration between shoe and rail for high-speed trains are studied by using a numerical simulation method, and the effects of train speed on the vibration law of shoe-rail interaction system are analyzed. The results show that both the maximum displacement of the rail and the maximum contact force between the shoe and the rail increase with the increase of the train speed. The bending moment of the rail, the maximum displacement of the shoe, the elastic and viscous forces of the shoe all decrease first and then increase. In particular, when the train speed increases from 275 to 300 km/h, the displacement, bending moment, contact force, and other mechanical quantities increase significantly, which indicate that it will lead to a sharp increase in vibration degree when the train speed exceeds 275 km/h. Therefore, in the case of actual operating parameters in this paper, it is recommended that the train speed does not exceed 275 km/h.

Li, Gang; Xu, Han; Ruan, Zhiyong; Liu, Qianjie; Gan, Yu; Yu, Lifan; Zhu, Wencai; Hu, Guoliang

doi: 10.1177/16878132241241435pmid: N/A

The performance of a semi-active suspension depends on the quality of the control algorithm. Considering the limitations of conventional PID controllers within intricate nonlinear systems, such as imprecise parameter tuning and performance deterioration, we introduced a fractional-order PID (FOPID) control strategy for vehicle semi-active suspension, this approach amalgamates fractional-order theory with conventional PID control to enhance both the controllable scope and precision of the suspension system. Research on semi-active suspension control was conducted using a nonlinear dynamic model of a quarter vehicle. Simulations and analyses were performed utilizing random road excitation and impact road excitation as input signals for both FOPID control, Fuzzy-PID control, and conventional PID control strategies. The analysis findings demonstrated that in the presence of random road excitation, the semi-active suspension system controlled by FOPID reduced vehicle body acceleration by 18.9%, in contrast to a 14.7% reduction by the Fuzzy-PID-controlled suspension, and a 12% reduction achieved by the PID-controlled suspension when compared to the passive suspension. In response to impact road excitation, the suspension system under FOPID control effectively mitigated the peak value of vehicle body acceleration by 29.4%, surpassing the 25.2% reduction achieved by Fuzzy-PID-controlled suspension, and the 24.6% reduction achieved by the PID-controlled suspension. The simulation outcomes substantiated that ride comfort and handling stability of the semi-active suspension system were effectively improved by the implementation of FOPID control.

Qu, Dongyue; Han, Jiyuan; Zhan, Yong; Zhang, Hongyi; Xu, Jian’an

doi: 10.1177/16878132241241466pmid: N/A

Machining-induced residual stress (MIRS) in thin-walled components affects their machining accuracy, especially for large-size thin-walled components. This study focuses on the bodies of marine diesel engines, exploring the distribution of MIRS and distortion caused by the gravity-coupled machining residual stress during the boring process of the main bearing hole. The research obtained the distribution of MIRS and the machining distortion based on the finite element method and the mapping method. It examined the influence rules of various parameters, such as the cutting speed, feed, and depth of cut, on MIRS and machining distortion. The study shows that cutting speed, feed, and depth of cut are vital factors affecting MIRS and machining distortion. For the machining distortion of large-size and thin-walled components, their own weight is an essential factor that cannot be ignored. By optimizing the wall thickness, the distortion range can be effectively controlled, supporting the lightweight design of the structure.