Browse Topic: Powertrains

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Influence of Roundness and Geometric Errors on Lubrication Performance of Engine Journal Bearings2026-99-03218/14/2026
This paper focuses on the critical issue of lubrication performance in journal bearing manufacturing, employing numerical simulation techniques to investigate how manufacturing errors from processing accuracy impact lubrication behaviors. As core components in mechanical systems—especially diesel engine crankshaft bearings operating under complex conditions—journal bearings’ lubrication performance directly determines equipment stability, energy efficiency, and service life. Manufacturing deviations-induced poor lubrication can cause increased friction, severe wear, or even failures, underscoring the research’s practical value. The study constructs a refined numerical model based on the Navier-Stokes equations within the Computational Fluid Dynamics (CFD) framework, ensuring it reliably depicts fluid flow in bearing clearances. It then systematically analyzes the lubrication responses of diesel engine crankshaft bearings under diverse operational scenarios, varying key manufacturing-related parameters: roundness degrees and clearance dimensions, which mimic real production discrepancies like tool wear or machining vibration. Additionally, the research explores shaft center trajectory variations under two extreme operating conditions, as shaft movement reflects the lubrication film’s loadbearing and stability capacities. Surface roundness and clearance are identified as pivotal to journal bearing performance: they significantly alter oil film thickness distribution—critical for avoiding metal contact—and determine the maximum fluid pressure within bearings, a key load-bearing indicator. Moreover, the amplitude and phase angle of roundness fluctuations (often overlooked) exert substantial impacts on lubrication stability and load-bearing properties, offering insights for optimizing manufacturing processes to mitigate such adverse effects: -Journal bearings. -hydrodynamic lubrication. -Form error.
Liu, Jun, Liu, Deliang
Research on the Fault Diagnosis Method for Key Components of Inertial Friction Welding Equipment2026-99-03098/14/2026
Inertial Friction Welding (IFW) equipment is essential for the welding process of aircraft engine shaft components. However, the absence of comprehensive fault-handling standards for domestically produced inertial friction welding equipment has hindered its further development. This study focuses on the connecting rod and motor of the 30T-IFW equipment, employing a model-based fault detection method. Through simulation, the deformation of the connecting rod and the frequency response of motor vibration acceleration under different working conditions are obtained. Additionally, a monitoring platform is proposed to collect real-time data on connecting rod deformation and motor vibration from actual welding equipment. By establishing a quantitative correlation model of connecting rod deformation-force and revealing the coupling mechanism between motor eccentricity faults and modal frequency vibrations, a hybrid diagnostic framework that combines simulation of primitive warning and measurement of calibration is proposed. At last, the simulation and experimental results verify the effectiveness of the fault diagnosis method proposed in this paper.
Yang, Haifeng, Yuan, Mingqiang, Sun, Tao, Liang, Wu, Gong, Maolin, An, Xingyi, Wang, Qisong, Liu, Dan
Design of a Four-Wheel Turning Tobacco Harvester Suitable for Hilly Areas2026-99-03338/14/2026
To address the core requirement of “layered ripeness and non-destructive harvesting” in tobacco-growing hilly regions of China, a specialized tobacco leaf harvester was developed. Considering the challenges posed by scattered plots and complex terrain, a four-wheel steering chassis system was proposed. The platform adopts a four-wheel independent drive and steering (4WID-4WIS) configuration, powered by DC servo motors and integrated with a microcontroller-based ROS system. The resulting drive chain—comprising motors, gear reducers, and off-road tires—achieves a maximum operating speed of 0.5 m/s. A novel rotary cross-blade harvesting module was designed in conjunction with a conveyor-based transmission mechanism, enabling stratified harvesting and leaf transport. Full-condition field tests were conducted. In terms of mobility, the harvester achieved stable operation at 0.5 m/s on cement roads, 0.1–0.2 m/s in fields, and demonstrated slip-free climbing on 20° slopes. In terms of harvesting performance, the system’s adjustable modules accommodated varying plant heights; however, issues with blade grip were observed when handling irregularly slanted stalks, affecting collection efficiency. During continuous field entry and exit operations, no mechanical failures occurred, verifying the prototype’s operational stability. This study introduces an innovative combination of omnidirectional mobile chassis and stratified blade modules, offering technical support for the modernization of tobacco agriculture. Further refinement of the harvesting strategy will be pursued to enhance practicality.
Guo, Ting, Gu, Jin, Li, Wen, Tang, Xiaoming, Long, Chao, Yang, Dongchao
Research on Asymmetric Gear Stiffness2026-99-03328/14/2026
To meet the need for optimizing the dynamic performance of asymmetric gear transmissions operating under high-speed and heavy-load conditions, this study presents a refined stiffness modeling approach. A tooth-surface contact stiffness model is formulated based on Hertzian contact theory. By integrating the energy method, a coupled stiffness model is established that incorporates bending, shear, axial compression, and foundation stiffness components. Stable curves depicting the variation of mesh stiffness with the path of contact are subsequently derived by leveraging the principle of stiffness superposition. The findings demonstrate that the proposed mathematical model accurately represents the stiffness behavior of asymmetric gears as governed by the changing contact length, thereby providing a theoretical foundation for enhancing gear dynamics and extending the service life of transmission systems.
Zhao, Zeyi, Sun, Xiaoyan, Wu, Ziheng, Tang, Xin, Liu, Yanxia, Li, Fajia
Design and On-Vehicle Validation of a Clutchless Electro-Pneumatic Gear-Shifting System for a Formula Student Race Car2026-01-50698/14/2026
Gear-shift execution is critical to power delivery, vehicle acceleration, and driver workload in Formula Student racing vehicles. Conventional shifting solutions for sequential gearboxes are often limited by driver-dependent operation, insufficient actuator authority, incomplete torque coordination, or the absence of closed-loop gear-state confirmation. This study develops and validates a clutchless electro-pneumatic gear-shifting system for a CF700-powered Formula Student vehicle equipped with an integrated sequential dog-engagement gearbox. The system is treated as a shift-assist form of automated manual transmission, in which the driver retains gear-selection authority while shift actuation and engine torque coordination are performed electronically. Although pneumatic shifting systems are already established in motorsport applications, the present work focuses on their vehicle-specific integration through measured shift-load characterization, geometry-based actuator design, gear-position-based closed-loop control, and electronic-throttle-assisted torque intervention. Vehicle tests were conducted under straight-line acceleration, high-speed obstacle-avoidance, and endurance-oriented training conditions. Across 76 recorded shift events, no failed gear transition or missed target-gear confirmation was observed. In straight-line acceleration tests, the mean target-gear confirmation time for recorded upshifts was 96 ± 5 ms, and the representative gear-position transition interval was approximately 20 ms. The full Engine Control Unit (ECU)-controlled upshift event was 0.50 ± 0.10 s because it included the calibrated low-torque dwell and torque-recovery phase, and should therefore be interpreted as a control-event window rather than the mechanical shift duration. After powertrain-specific actuation and torque-control calibration, the developed system provides an implementation basis for similar electronically controlled sequential-gearbox racing platforms, with potential to reduce shift time and driver workload and to support improved autocross drivability and performance.
Cao, Yuanyi
Dynamic Response Analysis of RV Reducers with Time-Varying Stiffness2026-99-09088/7/2026
As a high-precision transmission core component, the RV reducer’s performance depends on the time-varying stiffness of its core components. Building a time-varying stiffness model is essential for studying its dynamic characteristics. This paper addresses the lack of key factors in existing dynamic studies by creating a multi-factor coupled dynamic model. It analyzes the time-varying stiffness of the crankshaft bearing, involute gear, and cycloid gear-pin gear. The study also focuses on building a dynamic analysis model for the crankshaft bearing. By measuring changes in oil film thickness and initial assembly clearance caused by temperature rise, it explains how combined clearance affects bearing performance. To verify the model, a domestic RV reducer is modeled and assembled in SolidWorks. The simplified model is imported into ADAMS for simulation. Under set load and speed conditions, dynamic parameters like angular velocity and acceleration of core components are obtained. This provides a more scientific analysis method and data support for understanding the dynamic characteristics and improving the transmission performance of RV reducers.
Xuan, Liang, Teng, Shaowei, Huang, Ruizhe, Wan, Zefu, Shao, Mengqi, Yu, Zhishen, Wang, Ziyue
Mechanical Structure Design and Dynamics Simulation of an Exoskeleton Leg Rehabilitation Robot2026-99-09028/7/2026
In response to the challenges of training and rehabilitation for patients with leg dysfunction, this research focuses on two core requirements: “bionic adaptation” and “safety assistance”. It introduces a novel exoskeleton leg rehabilitation robot designed to support diverse rehabilitation exercises for individuals with leg disabilities during therapy. The robot system consists of a lumbar support structure, thigh mechanical components, calf mechanical components, leg fixation straps, and foot mechanical structures, and achieves multi degree of freedom motion simulation through three main joints: hip joint, knee joint, and ankle joint. Each mechanical leg has three independent degrees of freedom, which can effectively simulate the natural movements of the human lower limb, such as flexion, extension, abduction, etc., during the gait cycle, thus meeting the functional needs of patients for different movement modes during rehabilitation training. On the basis of structural design, this study further utilizes multi-body dynamics simulation software ADAMS to conduct kinematic and dynamic analysis of the exoskeleton robot. By simulating the joint torque of the exoskeleton legs under ideal working conditions, the rationality and smoothness of the mechanism design are verified. The simulation results not only reflect the performance of the robot in typical rehabilitation actions, but also provide a theoretical basis and data support for the selection and parameter matching of key execution components (such as servo motors, reducers, etc.), laying an important foundation for the physical development and control strategy optimization of the robot system.
Mu, Xiaoqi, Ma, Chao, Li, Weijie, Pu, Shuai, Liu, Jiaqi, Wang, Ruiyin, Zhang, Xiaodong
Research on Parameter Matching of Electric Vehicle Powertrain System2026-99-09058/7/2026
This paper focuses on the parameter matching of key components and the improvement of overall vehicle performance for a certain front-wheel drive pure electric vehicle. Firstly, based on the target performance of the vehicle, the rated/peak power, speed, and torque of the permanent magnet synchronous drive motor, as well as the capacity, voltage, and series-parallel scheme of the LiFePO4 power battery, are systematically calculated. Meanwhile, the gear ratio of the transmission system is determined based on the dual constraints of the maximum speed and the maximum gradeability. Subsequently, the vehicle model is built using AVL Cruise, and the maximum speed, 0-100 Km/h acceleration time, maximum gradeability, and NEDC range are simulated and verified under steady-state and transient conditions. The results show that the maximum speed of the prototype vehicle reaches 139 Km/h, the 0-100 Km/h acceleration is 7.98 s, the maximum gradeability is 33.2%, the power consumption per 100 Km is 12.12 KWh, and the range is 485 Km, all of which are superior to the design indicators. The research verifies the rationality of the proposed parameter matching scheme and can provide a theoretical basis and engineering reference for the forward development of the power system of pure electric vehicles of the same level.
He, Yuefan, Zhang, Baoping, Tang, Shujian, Chen, Hanbang, Jin, Biao
Automotive Engineering: August 202626AUTP088/6/2026
2026 Toyota RAV4 just the first to benefit from Arlene and Toyota's Woven City A dispatch from the automaker's "let's just try it" city finds hydrogen fuel cells, automated parking robots, and a robust spirit of innovation. Go ahead, lean into AI and smart testing HBK and VI-grade's Smart Prototypes Summit shows again just how fast the auto industry is moving. Fastener specification for EVs: what engineers need to know Breaking down the critical differences in fastener selection for EV platforms. The missing layer of engineering The next generation of materials and automotive breakthroughs will depend on a better understanding and engineering of microstructure. Editorial ITF Summit 2026: Engineering resilience The Navigator Planning a trek across America with dogs in EVs Mercedes AMG EV has three electric motors and the sound of a V8 Glazing creatively at Sekurit Imagine Lab Slate's modem-free pickup brings privacy back to driving 1.5 million km later: How Huber+Suhner connects the gangway GM Energy places bets on sodium batteries Road Ready Four electric SUVs, five states, 16 beagles Product Briefs Spotlight: Noise & vibration tech, machine tools Q&A The changing value of in-car data
Delay-Compensated Active Anti-Roll Bar of Tractor-Trailers Using Two-Dimensional Piston Pump Electro-Hydrostatic Actuators02-19-04-00278/5/2026
As tractor-trailers are essential to global logistics, their roll stability during emergency maneuvers is a critical safety concern. This paper presents a novel delay-compensated active roll control strategy for tractor-trailers using a two-dimensional piston pump electro-hydrostatic actuator (EHA). Unlike existing advanced strategies that assume ideal actuator behavior, this approach specifically targets the inherent response delay in high-tonnage applications. A detailed EHA model, including pump flow characteristics and hydraulic mechanics, was developed and validated through step response experiments. A seven-degree-of-freedom vehicle dynamics model and a model predictive controller were also constructed to compute the required anti-roll moment under emergency driving conditions. In order to address the EHA actuator’s response delay, a delay feedforward controller (DFC) was designed, integrating acceleration feedforward, feedback regulation, and delay disturbance estimation. TruckSim–Simulink co-simulations under double lane-change (DLC) maneuvers at 40 km/h, 60 km/h, and 80 km/h show that DFC improves displacement tracking and reduces peak trailer roll angle by up to 15% compared to a velocity-feedforward proportional-integral-derivative (VFPID) controller. It also enhances control efficiency, as evidenced by lower average motor speeds and pressure response of EHA. The system demonstrates high power-to-weight ratio and efficient tracking capabilities under dynamic conditions. Although active control provides limited benefit at low speeds, the proposed strategy effectively improves roll stability and driving safety under dynamic conditions.
Chen, Lijie, Yin, Yuming, Zeng, Yuhang, Ruan, Jian, Li, Hangqi, Sun, Peng
683 Guidance for Electronic Shop Reports in Aviation MaintenanceARINC683 (Current)8/4/2026
The purpose of this standard is to provide guidance for the content, format and two-way electronic exchange of data between a Service Provider and the Customer. The standard is focused on the production of an electronic Shop Findings Report by the Service Provider, and to promote automated electronic data exchange.
Aviation Maintenance Committee
Microwaves Enable 3D Printing of High-Performance CeramicsTBMG-555448/1/2026
3D printing could change how we build parts for jet engines and power plants, but the process leaves microscopic holes that cause the materials to shatter. Published in International Journal of Extreme Manufacturing, Professor Fangyong Niu’s team in Dalian University of Technology have fixed the problem by doing something unconventional: They added a microwave.
The Influence of Time-Varying Meshing Stiffness on the Vibration Characteristics of Gears in Electric Drive Axle Reducers2026-99-02057/31/2026
The dynamic characteristics of the electric drive axle of the new energy commercial vehicle is an important performance to evaluate its quality, and the dynamic performance of the two-stage helical gear transmission system in the electric drive axle reducer directly reflects the dynamic performance of the electric drive axle. This study focuses on the secondary gear transmission system of the electric drive axle reducer of the new energy commercial vehicle, and mainly studies the influence of the tooth surface contact stiffness with the change of meshing on the vibration performance of the transmission system. Through establishing the coupled nonlinear dynamic model of torque-begear shaft of high-speed helical gear, the dynamic equations of the system under the influence of time-variable contact mesh stiffness are derived. Taking gear error excitation and support stiffness into consideration, a 3D model software is used to build the simulation virtual model of bevel gear of electric drive axle reducer, and the dynamic simulation analysis of its transmission system is carried out. By setting different tooth contact stiffness coefficients, the variation rules of translational vibration acceleration, angular acceleration and spectrum response of transmission gears are studied systematically. Simulation results indicate that selecting the contact stiffness coefficient within 80% to 90% of the average mesh stiffness value leads to improved meshing performance in the gear transmission system of an electric drive axle reducer. This configuration results in reduced vibration amplitude, narrower sidebands, and decreased dynamic transmission error, thereby effectively enhancing the NVH performance of the transmission system. The findings also provide an important reference for optimizing the meshing behavior of electric drive axle reducers.
Pan, Yunping, Song, Junchen, Du, Shuai, Wu, Changquan, Liao, Lieping
Design and Analysis of a Large Hydraulic Cylinder Maintenance Device2026-99-02147/31/2026
Addressing the challenges in maintaining large hydraulic cylinders and the lack of specialized equipment, this study presents a dedicated maintenance system developed through a case study of a large hydraulic lifting cylinder. Through a comprehensive analysis of maintenance requirements, we developed a six-component maintenance system comprising a foundation base, a mounting bracket, a cylinder support frame, a piston rod bracket, a drive cylinder bracket, and hydraulic components. The paper systematically explains the structural configurations and functional specifications of each component, details the operational workflow of the maintenance system, and conducts theoretical design and strength verification for critical load-bearing brackets using principles from theoretical mechanics and structural mechanics. A static analysis module from ANSYS Workbench finite element software was employed to validate the overall structure. Results demonstrate that the key components meet operational strength requirements. This innovative maintenance system proves highly feasible and serves as a valuable reference for designing similar hydraulic cylinder systems.
Qiao, Xiaodong, Du, Chao, Long, Yuheng
Research on the Axial Assembly Stress and Fatigue Life of 60-Series Harmonic Reducers2026-99-01917/31/2026
This study presents a systematic investigation into the assembly stress and fatigue life of 60-series harmonic reducers. A sophisticated finite element simulation model is constructed to precisely simulate the real assembly process and calculate stress distribution in the flexspline under axial assembly errors. In addition, corresponding fatigue life tests are designed to explore the influence of different axial assembly errors on the number of rotation cycles and transmission efficiency of the harmonic reducer. By comparing the predictions of the fatigue life mathematical model with the test data, a reliable fatigue life prediction method is established, providing a solid theoretical basis for the whole-machine assembly process and reliability design of this series of harmonic reducers.
Du, Yuefei, Qiu, Haodong, Fan, Yong, Li, Ziyuan, Dong, Yi, Zhang, Chi, Li, Chenzheng, Li, Yuan
Research on Electromagnetic Characteristics Calculation of Small Lead Bismuth Ring Linear Induction Electromagnetic Pump Device2026-99-02017/31/2026
Compared to traditional reactors, lead-bismuth eutectic reactors (LBE) have higher neutron economy and stability. As a device for driving the coolant, the electromagnetic pump features non-contact operation, simplifying the sealing apparatus and achieving complete sealing inside the pump. It meets the requirements of miniaturization and modularity, while offering excellent flow regulation performance. Its input parameters determine the output performance in both performance analysis and structural design of lead-bismuth electromagnetic pumps . This article focuses on a small-scale annular linear induction electromagnetic pump (ALIP) as the simulation object and establishes an electromagnetic pump model. Based on Maxwell’s equations and N-S equations, and with the background of three-dimensional multiphysics coupling of electromagnetic field, flow field and heat transfer field, the coupling mechanism between the flow velocity of LBE and the Lorentz force was studied in detail. From the perspective of electromagnetic-flow coupling, the influence of different coil turns, input currents, and excitation frequencies on the Magnetic flux density and pressure of electromagnetic pumps was analyzed. Finally, a comprehensive analysis of the output characteristics of ALIP under various input parameters is performed, and the research results provide a theoretical reference for the design and optimization of lead-bismuth ALIP.
Peng, Chunyu, Xiao, Changzhi
Angular Vibration Model of Frictional plates in High Speed Open Wet clutch2026-99-02347/31/2026
High-speed wet clutches may experience dynamic instability between the friction plates, leading to rattling vibrations and a significant increase in drag torque. This study employs a homogeneous flow model to characterize the gas-liquid two-phase flow within a high-speed clutch. It establishes a dynamic model for the angular oscillation of friction plates. Finite-element numerical simulations and stability analyses were conducted. The results indicate that as the clutch speed difference increases, the density and viscosity of the two-phase flow decrease rapidly, leading to a sharp reduction in fluid stiffness and damping. Consequently, the friction plates become more susceptible to angular oscillation. The stability of angular oscillation is determined by two key parameters: dimensionless comprehensive stiffness and critical frequency ratio. Higher dimensionless comprehensive stiffness and a lower critical frequency ratio enhance oscillation stability. Numerical evaluations of various groove types reveal that as rotational speed and friction plate clearance increase, the fluid stiffness coefficient, damping coefficient, dimensionless comprehensive stiffness, and critical moment of inertia all decrease, thereby reducing angular oscillation stability. Among the tested groove geometries, enclosed grooves and spiral grooves exhibit superior stability due to their strong hydrodynamic effects, yielding the highest dimensionless comprehensive stiffness. The critical frequency ratio for the self-excited angular oscillation of friction plates is approximately 0.5, termed the half-frequency oscillation characteristic. Experimental data validate the proposed angular oscillation model and its frequency response, providing a theoretical foundation for performance prediction and stability optimization in high-speed clutch design.
Cheng, Xu, Peng, Zengxiong, Zhang, Jing, Jin, Jiayin
Design of an Automatic Device for Snow Clearing of Solar Greenhouses2026-99-01467/31/2026
Solar greenhouses in winter or mountainous areas can be at risk of roof snow accumulation, leading to collapse, poor lighting, and sudden drops in temperature. The snow removal technologies presently employed on these greenhouses have the disadvantages of being cumbersome to adjust, being intricately structured, having a high cost, having high energy consumption, and being poorly adaptable to the curvature of the plastic. An intelligent snow removal device for removing snow on a northern solar greenhouse roof, and an automatic alarm safety system were designed to solve the problems. The device consists of a snow-clearing mechanism, a traversing mechanism, and detection-alarm modules. The mechanism for snow removal consists of a crank-slider with a curved guide rail. The snow removal rod is driven by the gear motor, which goes back and forth on the arched top. A bevel gear transmission system drives the gear motor mechanism. Due to this, the transverse mechanism moves with an interrupting jump-action on transverse rails around many different zones. The system for monitoring snow pressure has a distributed sensor that is programmed as a shield using an Arduino software system. The sensors detect the pressure of the snow in real-time. When the snow pressure hits the threshold, it activates the mechanism for coordinated functioning. This mechanism triggers snow clearing when the pressure threshold is achieved to avoid energy consumed through “premature clearing”. It also fits well on the curved surfaces of the greenhouse without any jamming. The snow removal machine’s various components and operations would accomplish full span snow removal and make it possible to overcome high labour intensity, slow manual response, energy waste, and others. The technology can enhance the safety of winter production of northern greenhouse crops and improve the disaster-resistant capacity of modern agriculture facilities. This technology has been granted a patent for invention.
Fu, Chengguo, Wei, Shanxiang, Zhang, Rongxian, Ding, Xuefeng, Gao, Yulan
Research and Development of Wheelchair Assisted Intelligent Boarding and Landing Device for Barrier-Free Bus Based on TRIZ Theory2026-99-01477/31/2026
With the intensifying global trend of population aging, enhancing public-transport accessibility for seniors and people with disabilities has become critical. Current wheelchair-assist boarding devices on low-floor buses suffer from cumbersome operation, excessive space occupation, poor adaptation to varying curb heights, and an inability to modulate power output dynamically, all of which compromise travel convenience. This study applies TRIZ theory to solve these problems. Functional analysis, causal-chain analysis, and the nine-screen method were used to identify key issues: excessive space use, insufficient dynamic power adjustment, poor curb-height adaptability, and the lack of self-service capability. TRIZ tools— including the contradiction matrix, substance-field models, and the Ideal Final Result (IFR)—generated conceptual solutions such as a foldable ramp, an adaptive tilting mechanism, an intelligent power-assist system, and an automatic extension device. The resulting integrated unit employs a planetary-gear train combined with a four-bar linkage for compact folding, a servo motor with torque-limiting springs for adaptive height adjustment, torque sensors for real-time power modulation, and a scissor-type telescoping mechanism for automatic stowage. Experimental validation through 50 trials showed that the device completes extension/folding in 7 s, achieves angle adjustment within 3.5 s, covers a pitch range of 0°–43°, and attains a 100 % extension success rate. These features significantly increase automation, adaptability, and user independence, thereby improving the quality of accessible bus services.
Zhu, Zongchuang, Hu, Zhiyong, Liu, Zeshuo, Liu, Yijia, Zhang, Ziqian
Design and Optimization of Hollow Rotating Traveling Wave Ultrasonic Motor Based on Laser Beam Expander2026-99-01547/31/2026
To meet the critical need for rapid response and miniaturization in laser beam expander drive systems, this study proposes an innovative actuation solution based on a hollow rotary traveling-wave ultrasonic motor. By thoroughly analyzing the optical adjustment mechanism of laser beam expanders and the electromechanical coupling behavior of ultrasonic motors, the motor structure was systematically optimized. Using a multiphysics coupling approach, the performance of stators fabricated from three distinct materials was compared, and parametric optimization was conducted. Experimental verification confirms that the developed ultrasonic motor precisely matches the load characteristics of beam-expanding optics while fulfilling the stringent requirements for both fast response and compact design. This research provides a reference for the miniaturization drive of high-precision optical systems, with promising applications in space optics and precision instrumentation.
Qiu, Haihui, Niu, Chuanhu, Xiao, Zhong, Xu, Zhangfan, Li, Jialiang, Pan, Song
Development and Technical Verification of A Lunar Dust Environment Simulation Mechanism2026-99-01757/31/2026
Lunar dust consists of extremely fine particles and exhibits electrostatic charging properties and electrostatic adhesion. These characteristics cause lunar dust to be highly susceptible to mobilization during lander touchdowns, rover traversals, and human activities, forming widely distributed dust clouds. Lunar dust contamination not only abrades spacecraft and equipment to impair their performance but also poses a threat to astronauts’ safety. To verify the impact of the lunar dust environment on exploration equipment components, a simulation mechanism adaptable to the thermal vacuum test environment was designed. This mechanism is integrated into the lunar environment simulation system and uses a vacuum stepper motor to drive a ratchet mechanism, enabling precise vibrational injection of simulated lunar dust. It mainly consists of a pretreatment mechanism, a particle sedimentation mechanism, a shielding mechanism, and an ultraviolet (UV) irradiation system. Considering the vacuum operating environment, alternating high and low temperature conditions, as well as the strict requirements for the mechanism’s compact size and high reliability, this paper analyzes in detail a series of problems encountered during the development of the mechanism and their corresponding solutions. Stainless steel and polytetrafluoroethylene (PTFE) were selected as the main materials for the mechanism. Meanwhile, active temperature control measures were adopted to actively regulate the temperature of components such as the motor. Ultimately, the mechanism can withstand alternating high and low temperatures ranging from -150°C to 150°C and a vacuum environment of 5 × 10^–6 Pa. Under this environment, the mechanism can achieve vibration frequency adjustment within the range of 1-5 Hz, and realize the sedimentation of simulated lunar dust particles with a particle size of less than 200 μm over an area of 150 mm × 150 mm. After sedimentation, the simulated lunar dust particles can be charged through the photoelectric effect.
Xu, Menglong, Lv, Shizeng, Li, Guohua, Gong, Jie
Study on the Electromechanical Coupling Torsional Vibration Characteristics of Electric Drive Transmission Systems under Motor Harmonic Excitation2026-99-02297/31/2026
Considering the spatial harmonic and time harmonic excitation of the permanent magnet synchronous motor, and the dynamic meshing excitation of gear pairs, this paper constructs one electromechanical coupling torsional vibration model. The torsional vibration characteristics of the electric drive transmission system in pure electric vehicles are investigated. Key electromechanical parameters are obtained by numerical calculations, and the electromechanical coupling system model is solved using the Runge-Kutta method. Finally, the system dynamic response characteristics at rated speed of 3000 r/min are analyzed. The results indicate that the significant bidirectional coupling exists between the electromagnetic excitation of the motor and the mechanical excitation of the gear transmission system. The current spectrum contains fundamental and harmonic components, along with components of gear meshing frequencies and their modulated sideband characteristics relative to the electrical frequency. The electromagnetic torque spectrum exhibits components of gear meshing frequencies, and gear angular velocity fluctuations are influenced by motor harmonic excitation. Under multi-source excitation, this study reveals the frequency modulation mechanism of torsional vibrations in electromechanical coupling drive systems, providing a theoretical basis for vibration and noise suppression.
Luo, Yaou, Zhao, Kaihua, Fu, Shengping
A Methodology for Assessing Inlet Swirl DistortionAIR5686 (Current)7/31/2026
This Aerospace Information Report (AIR) addresses the subject of aircraft inlet-swirl distortion. A structured methodology for characterizing steady-state swirl distortion in terms of swirl descriptors and for correlating the swirl descriptors with loss in stability pressure ratio is presented. The methodology is to be considered in conjunction with other SAE inlet distortion methodologies. In particular, the combined effects of swirl and total-pressure distortion on stability margin are considered. However, dynamic swirl, i.e., time-variant swirl, is not considered. The implementation of the swirl assessment methodology is shown through both computational and experimental examples. Different types of swirl distortion encountered in various engine installations and operations are described, and case studies which highlight the impact of swirl on engine stability are provided. Supplemental material is included in the appendices. This AIR is issued to bring together information and ideas required to address the inlet-swirl problem for which common industry practice has yet to be established. This document should foster the tests and analyses necessary to mature the ideas proposed by the committee to a recommended practice. These tests and analyses must include information that justifies three main features of the proposed swirl methodology: (1) swirl descriptors for correlating inlet swirl and stability pressure ratio loss, (2) computational techniques for analyzing compression systems (inlets, fans, compressors), and (3) test protocols (instrumentation and test techniques). The committee anticipates serving the industry by using such information to establish the consensus necessary for issuance of an SAE recommended practice.
S-16 Turbine Engine Inlet Flow Distortion Committee
Research on Reliability Test Methods for Electric Drive Axle Differentials2026-01-50447/31/2026
With the rapid development of the global economy, issues such as the energy crisis and environmental pollution have become increasingly severe. Owing to their environmental friendliness, structural simplicity, and high energy efficiency, electric vehicles have attracted widespread attention. Electric drive technology serves as the most promising and versatile propulsion solution for battery electric vehicles, hybrid electric vehicles, and fuel cell vehicles. As an advanced mechatronic transmission system, the electric drive axle offers high transmission efficiency, flexible packaging, and ease of digital and active chassis control integration, and has thus been increasingly adopted in modern vehicle architectures. The differential is a key component within the electric drive axle, responsible for regulating the rotational speed difference between the left and right wheels and ensuring balanced torque distribution. It plays a decisive role in vehicle stability and traction performance. This study focuses on the reliability testing methodology for differentials in electric drive axles, primarily including the extraction of reliability test conditions and the feasibility analysis of the proposed testing scheme. Specifically, based on the parameters of a given electric vehicle, a Simulink model of the motor and differential is established, and a complete four-wheel-drive vehicle model is constructed. Through simulation under typical driving conditions, operational data of the rear-drive axle differential are obtained. The collected data are then preprocessed and subjected to dimensionality reduction using Principal Component Analysis. The selected principal components are further analyzed using K-means clustering to construct representative differential reliability test conditions. The limitations of existing testing methods are analyzed based on the simulated results and relevant literature. Finally, a reinforced fatigue testing method for the differential is designed according to the extracted test conditions, and the feasibility of the corresponding test bench is evaluated.
Zheng, Hongyu, Li, Ziyu, Wang, Dajiang, Tian, Kai
Collapse Strength and Crush Space Analysis in Lateral Side Pole Impact of an Electric Vehicle2026-01-50527/31/2026
High-Voltage Battery (HVB) protection in lateral pole impact is very important due to severe nature of the impact. Unlike frontal impacts, vehicles have limited range of space and capacity to absorb kinetic energy in lateral side impacts. Nowadays, computer-aided engineering (CAE) using finite element analysis (FEA) is utilized routinely to simulate high-speed crash events of varied type, including side pole impact. These CAE applications focus on the analysis and design of HVB when the vehicle structure is well-developed. CAE methods are time-consuming and are not suited during the pre-program stage when the structure is only in a concept stage and not even a reasonable CAD is available/developed in any sense to use these methods. There is no analytical tool available to understand how to define the characteristics of the structure that surrounds and protects the HVB. The primary motive of this publication is to help with this aspect of vehicle planning/development. Needless to state that this procedure can also be used in planning/developing of internal combustion engine (ICE) and hybrid vehicles, as well. The objective therefore is to develop a simple method/procedure that can give reasonably accurate estimation of the collapse/crush force required for a specified crush space and hence protect the critical components, such as HVB and fuel tank. This analytical method also gives some insight into the optimal use of the upper body (rocker and floor cross-members) and underbody (ladder frame) parts. It was found, for a problem under consideration, optimum kinetic energy to be absorbed by the upper body is 32.5% to avoid intrusion into HVB.
Alavandi, Bhimaraddi, Midoun, Djamal, Frank, Randy
Research on the Control of Magnetic Weakening Scheme for the Voltage Utilization Rate of Hybrid Transmission2026-01-50497/31/2026
This paper proposes a field-weakening control method for permanent magnet synchronous motor (PMSM) current regulators based on the ratio of voltage-frequency ratio and voltage utilization rate when the motor speed exceeds the field-weakening speed; that is, the direct-axis offset current id is generated through the action of field-weakening feedforward and field-weakening PI regulator, and the control of field-weakening speed can directly adjust the demagnetization effect of id to achieve field-weakening control of PMSM. The field-weakening control method of PMSM current regulators with the outer loop of voltage utilization rate is adopted. It is proposed to use the phase-locked loop control method to decode the motor position signal in a closed loop and calculate the motor speed. The fluctuation of the position signal is reduced and the signal is more stable. This paper realizes constant power speed regulation based on high voltage utilization rate and field-weakening control method at high-speed operation above the base speed, which greatly improves the dynamic performance and system efficiency of the system.
Jing, Junchao, Zhang, Junzhi, Yan, Xiaoqian, Liu, Yiqiang, Sun, Fengjiao, Dai, Zhengxing
Advanced Damping Force Modeling Using Machine Learning for Next-Generation Electric Vehicle Suspensions2026-01-50537/31/2026
The rapid evolution of electric vehicles (EVs) has led to the development of innovative approaches to optimize ride comfort, handling, and the overall suspension performance. EVs introduce unique challenges due to their distinct weight distribution, powertrain dynamics, and noise characteristics, unlike their conventional internal combustion engine (ICE) counterparts. This paper outlines an advanced damping force modeling methodology using machine learning (ML) techniques to enhance the suspension design process for next-generation EVs. The analysis is based on data-driven ML algorithms, i.e., Gradient Boosting, Random Forest, and Neural Networks, to simulate the nonlinear and frequency-dependent phenomenon of dampers in different operating conditions. A comprehensive dataset, generated through simulation and experimental testing, captures the effects of road profiles, vehicle dynamics, and damping settings. Additionally, this research evaluates the impact of machine-learned damping force predictions on critical ride and handling metrics, including ride comfort, road-holding ability, and energy efficiency. The results demonstrate that the ML models can enhance the iterative design process considerably and help to create the adaptive suspension systems that will address the particular requirements of EVs. This paper contributes to advancing the state-of-the-art of the suspension modeling, incorporating the ML-based insights in the development cycle. It highlights the possibility of artificial intelligence to transform suspension design, paving the way for superior ride quality and vehicle performance in electric mobility.
Hazra, Sandip, Tangadpalliwar, Sonali, Khan, Arkadip
Development of Electric Vehicle Oils with High Energy Efficiency and Cooling Performance by Applying Novel Friction Modifier2026-01-50647/31/2026
Improving the efficiency of electric vehicle (EV) transmissions can help to extend the driving range of EVs, and the EV oil used in these transmissions plays an important role. In this study, in order to enhance energy efficiency, we examined the effects of lowering viscosity, traction, and friction in EV oil. While friction modifiers (FMs) have been widely used as friction reduction technologies in the field of tribology for many years, we previously developed a new FM that reduces friction in drive units. We found that a combination of lowering viscosity and using the developed FM was effective for better energy efficiency. The oil formulated with the developed FM improved efficiency by approximately +0.8% to +0.9% compared to commercial EV oil. EV oil also requires cooling performance. We assumed that reducing heat generation through friction reduction would improve cooling performance and examined the effect of lowering viscosity, traction, and friction. Consequently, it was found that a combination of lowering traction and applying the developed FM is effective for reduction in parasitic heat losses. We also examined durability, which is an issue when reducing viscosity. The results suggested that the oil formulated with the developed FM had good durability for gears and bearings. Thus, we succeeded in developing an ultra-low-viscosity EV oil that has excellent energy efficiency and high cooling performance.
Nakamura, Toshitaka, Furuse, Takashi, Hasegawa, Shinji, Akahori, Shinya, Itou, Kimikazu, Sakurada, Soichiro, Akiguchi, Junnosuke
Design and Optimization of Diesel Engine Cold Start Heating System under Extreme Cold Conditions2026-99-08097/30/2026
With the goal of enhancing diesel engine adaptability to low-temperature environments and exploring cold-start potential at - 50 °C, this paper develops a one-dimensional simulation model for the cold-start system. The model is based on a method that utilizes a diesel heater to warm the coolant, which in turn heats the engine block and oil. The heating condition of coolant and oil of a 10-cylinder V-type engine within a specified time under a -50 °C environment is studied through simulation. We further optimized the cold-start process by enhancing the coolant flow distribution within each circulation circuit to improve overall thermal management and start-up efficiency. The results show that: at an ambient temperature of -50 °C, with a heating power of 80 kW, a total flow rate of 110 L/min, and an engine block flow rate of not less than 54 L/min, the diesel engine can raise the coolant temperature at the engine outlet to 40 °C and the oil temperature to -35 °C within 20 minutes. Through flow optimization, by maximizing the flow rate of the engine block heating circuit and reducing the flow diversion of the intercooler, the coolant temperature at the engine outlet can reach 40 °C in 18.9 minutes, while the oil is heated to -34.9 °C, and the final heating coolant temperature reaches 44.4 °C at 20 minutes. Compared to the situation without flow optimization, the time for the engine outlet coolant temperature to reach 40 °C was shortened by 0.55 minutes, and the final heating coolant temperature increased by 2.2 °C. Based on relevant experiments and the dynamic viscosity curve of 5 W engine oil, this paper holds that the starting conditions of a diesel engine can be met when the engine outlet coolant temperature reaches 40 °C, and the engine oil temperature reaches -35 °C.
Wang, Jingfei, Xie, Peng, Wang, Zhuo, Xia, Yingqiu, Zhang, Xiaodong, Chen, Ke, Wang, Guodong
Research on Thermal Design of a Forced Air-Cooled Display Control Console2026-99-08087/30/2026
In this paper, the simulation software was used to conduct a thermal analysis of the design scheme of a certain type of forced air-cooled display and control console, and the results were compared with the experimental results. The results show that in an environment of 50 °C, the maximum temperature of the chip on this strong display control console does not exceed 98 °C, meeting the usage requirements of the chip and the thermal reliability requirements of the display control console. The thermal design scheme of the display and control console proposed in this paper has the advantages of a simple structural form, good heat dissipation effect, low fan noise, and consideration of the heat dissipation of multiple heat sources. It can provide a good reference for the thermal design of similar display and control consoles.
Li, Yun
Effects of Equivalence Ratio on Hydrogen Combustion Flow and NOX Emission Characteristics in a Jet-Trapped Vortex Combustor2026-99-08067/30/2026
The jet-trapped vortex combustor presented in this study was designed based on the trapped vortex combustor with good flame stability by introducing a jet flame-stabilization method. Leveraging the superior air-fuel mixing efficiency and enhanced heat and mass transfer of the jet stabilization method, this configuration addresses the inherent limitations of heat and mass transfer between the mainstream flow and the cavity in a conventional trapped vortex combustor. To investigate the influence of different hydrogen-air equivalence ratios on the flow dynamics, combustion performance, and emission within the jet-trapped vortex combustor, numerical simulations were conducted in this study. The results show that under different equivalence ratios, a vortex pair structure can be formed in the mixing zone between the hydrogen jet and the air jet. Complete combustion can be achieved at all equivalence ratios except for Φ = 1.56. When Φ is below 0.86, the axial distance required to achieve complete combustion progressively decreases as the equivalence ratio is reduced. The temperature distribution in the combustor is more uniform with minimal variation, and the concentration of NO emissions decreases progressively. Among these cases, the combustion efficiency, temperature distribution, and NO emission characteristic of the combustor are relatively better at Φ = 0.34.
Yan, Pinghua, Hou, Xinglong, Ren, Guanlong, Sun, Haijun, Luo, Kun, Yang, Shucheng
Design and Verification of Underactuated Coupled-Commutation Omnidirectional Mobile Integrated Camping Robot Chassis2026-99-08207/30/2026
To solve the poor mobility of traditional camping vehicle chassis in complex terrains and confined spaces, this paper proposes an underactuated omnidirectional mobile chassis for outdoor camping vehicles. The chassis adopts a coupled commutation mechanism (double-crank elastic special-shaped connecting rods cross sliders), allowing each wheel to realize two motion modes (omnidirectional translation, in-situ rotation) with just one drive motor, reducing system complexity and cost. A control system based on the RoboMaster Development Board C Type integrates PID angle-loop control and motor speed-current dual closed-loop control for motion stability. Kinematic models for these two modes are established to derive the wheel parameter-chassis motion relationship. MATLAB R2023b-ADAMS 2024 co-simulations show the chassis maintains attitude stability under S-shaped curve, circular curve, and in-situ rotation; Qualisys 3D motion capture experiments confirm its stable attitude in omnidirectional movement.
Ren, Yulong, Lu, Zhiguo, Yang, Dongsheng, Wu, Di, Zhang, Tianyu, Qian, Zhenxin
Research on Integrated Design and Optimization Method of High Speed Shuttle UUV Rudder and Propeller2026-99-08647/30/2026
Along with the advancement of the maritime power strategy, the research, development, and application of deep-sea space stations are becoming increasingly important. However, since deep-sea space stations mainly rely on acoustic communication, they cannot exchange information with ground stations quickly and accurately. To improve data transmission efficiency, this paper proposes using a high-speed shuttle UUV instead of acoustic communication. In this context, an efficient propulsion system is critical as it enables the UUV to achieve high speed and maintain stability. A propeller meeting the 110.9 N thrust requirement is designed using the chart design method, and the 110BL230-630 brushless DC motor is selected based on motor–propeller matching. This motor has a rated speed of 3000 rpm, rated power of 3000 W, and torque of 9.6 Nm. The performance curve of the NACA0012 airfoil is analyzed to select an appropriate rudder surface. The rudder area (4067 mm^2) is designed in accordance with DNV rules, with the following parameters: tip chord length 40 mm, root chord length 40 mm, and half-span 70 mm. CFD analysis is conducted on the designed propeller and the UUV equipped with the integrated propulsion system. The predicted performance of the P4119 propeller (hydrodynamic parameter deviation ≤ 1%) and the SUBOFF hull (resistance relative error ≤ 3.04%) confirms the accuracy of the CFD method for calculating propeller open-water performance and UUV drag. Through comparative analysis, the optimal rudder–propeller spacing is determined to be 60 mm, as this spacing yields the highest propulsion efficiency.
Wei, Jiaguang, Feng, Xiaowei, Zhao, Fuchen, Wang, Xingke, Xu, Shanzhi, He, Wenxuan
Experimental Study on the Temperature Impact of a Typical Cabin Fire on Adjacent Cabins2026-99-08667/30/2026
The cabins of ships are mainly made of steel. When a fire breaks out, the temperature inside the cabin rises rapidly, and an extensive body of heat spreads through the bulkheads to adjacent cabins. Understanding the variation law of the temperature field in adjacent compartments after a fire occurs in the compartments is of great significance for the research on the thermal safety of ship compartments. This paper designs an L-shaped cabin test system. We conduct fire tests of different scales and obtain the temperature distribution of adjacent compartments. The test results show that as the fire area in the pool keeps rising, the temperature in the adjacent compartments keeps rising. Due to the fact that an extensive body of high-temperature smoke produced by combustion is suspended at the ceiling of the compartment of fire, the temperature of the vertically adjacent compartments is higher than that of the horizontally adjacent compartments.
Hu, Wei-guo, Hu, Yang, Wei, Jin, Yuan, Ya-long
Structure Design of Toothed A/C Double Pendulum Milling Head2026-99-08567/30/2026
High-precision five-axis machining puts forward strict requirements for the stiffness and position stability of the AC double-angle milling head, especially when the gear transmission system is used under heavy cutting load and complex force coupling conditions. In the actual processing environment, the non-uniform deformation caused by structural coupling and load changes will directly affect the machining accuracy and stability. In order to solve these problems, this paper designs and analyzes a gear-type AC double-angle milling head with a pendulum structure and a layered modular structure. A parametric finite element model was established, and ABAQUS software was used to conduct a static analysis of two typical A-axis directions (0° and 90°), taking into account the internal prestressing force generated by gravity, cutting force, and gear meshing to reflect the typical working conditions. Under the same boundary conditions and load conditions, the influence of different structural materials on the overall stiffness was further studied through comparative analysis. The results show that under the conditions of five-axis linkage machining and positioning machining, the overall deformation of the milling head is maintained within the micron range, which meets the requirements of high-precision machining. The deformation behavior shows obvious dependence on the A-axis direction, reflecting the inherent anisotropic stiffness characteristics of the structure. Compared with the traditional structure, the proposed design has better rigidity performance under combined load conditions and provides practical reference values for the subsequent structural optimization, material selection, and precision control of high-performance five-axis CNC milling heads.
Xie, Xingui, Yuan, Yongchao, Qi, Quan, Li, Xiangshuai
Topology Optimization of Liquid Flow Manifolds for Flow Resistance Reduction in EV Thermal Management2026-99-08657/30/2026
In order to reduce flow resistance loss in EV thermal management systems, this research builds a comprehensive computational process. The study used an advanced three-dimensional topology optimization technology integrating detailed fluid flow analysis with an adjoint sensitivity solver. This integrated computational approach helps systematic analysis of the complete design region. Thus, the internal flow channels with high resistance can be rearranged. The optimization target was set to minimize total pressure drop under defined operational parameters in real driving conditions. Through iterative calculation, the study successfully created three flow manifolds with different geometric shapes; each flow channel has its own distinct source of high resistance. The results show that the optimization effect is quite good, compared with the traditional manifold developed based on engineering experience; these optimized designs have reduced the pressure drop by 27%, 41%, and 74%, respectively. Beyond these quantitative pressure reduction data, detailed flow field analysis revealed that the optimized manifolds promote substantially improved hydrodynamic characteristics. The optimized internal channels generate more uniform velocity profiles, effectively diminish spatial velocity variations, and restrain vortex formation and recirculation zones. These useful flow field enhancements collectively contribute to a dramatic reduction in energy dissipation. This improves the thermodynamic efficiency of the thermal management system effectively. In order to conduct a more comprehensive verification, the optimized manifold was evaluated under various non-design operating conditions. These three designs consistently maintained stable performance characteristics and their low resistance properties in operating scenarios different from the original conditions, compared to the original manifold. Its stable performance under variable conditions shows the effectiveness of the topology-optimized methods and shows its broad operational adaptability. This is of great significance for the automotive application field, as the operating conditions in this field are often changing.
Liang, Zhixuan, Tian, Ran, Ye, Xiaokang, Wei, Mingshan, Sun, Xiaoxia, Shen, Lili
Co-optimization of Energy Efficiency and Drivability for Dual-Motor Electric Commercial Vehicles: A Topology-Aware Hierarchical Approach02-19-04-00267/29/2026
Dual-motor architectures provide additional operating degrees of freedom for electric commercial vehicles (ECVs), but the integration of automated manual transmissions (AMTs) introduces torque discontinuities during gear-related mode transitions. Existing energy management strategies usually focus on steady-state efficiency optimization, while the mechanical feasibility of mode transitions is often considered separately or neglected. To address this issue, this study proposes a topology-aware hierarchical control framework for dual-motor ECVs. The framework combines an offline global efficiency map with an online transition-feasibility arbitration mechanism. In the offline layer, the energy-oriented operating mode and torque split are extracted over the vehicle-speed and wheel-torque domain. In the online layer, a topology-based transition matrix is used to identify mechanically singular mode transitions, and potentially torque-interrupting commands are re-routed through feasible bridge modes. The proposed method embeds powertrain topology constraints into the real-time implementation of an offline optimal map, thereby complementing conventional global optimization methods with transition-feasibility arbitration. Simulation results under the CHTC driving cycle show that the proposed strategy improves torque continuity during mode transitions while retaining most of the energy-saving benefit of the unconstrained efficiency-oriented strategy. Compared with the rule-based strategy, the proposed method reduces SOC-equivalent energy consumption by 10.7%, and recovers 65.5% of the DP-achievable energy-saving potential. Hardware-in-the-Loop (HIL) results further demonstrate that the proposed online arbitration logic can be executed within the controller sampling period.
Song, Dafeng, Chen, Lexin, Zeng, Xiaohua, Ni, Lixin
Performance Analysis of a Gasoline Direct-Injection Opposed-Piston FPEG: A Coupled Study of Injection, Scavenging, and Dynamics2026-01-50637/28/2026
The opposed-piston free-piston engine generator (FPEG) is a promising high-efficiency energy conversion architecture, featuring reduced heat transfer and favorable NVH characteristics for applications such as auxiliary power units and vehicle range extenders. While significant progress has been made, existing studies often focus on isolated parameters. The coupled effects of key operational parameters, including injection pulse width, scavenging pressure, rebound cylinder base pressure, and mover mass, on the performance of gasoline direct-injection opposed-piston FPEG remain insufficiently explored. To bridge this gap, we develop and validate a thermodynamics zero-dimensional combustion simulation model against bench tests, with peak pressure errors below 5%. This model enables a systematic investigation into the interactive effects of these parameters. Results indicate that piston dynamics are most sensitive near dead centers and in the first half of the expansion stroke. Indicated thermal efficiency peaks at 35.87% with a 4.5 ms injection pulse width and increases from 35.02% to 36% as scavenging pressure rises from 1.3 bar to 3 bar. Scavenging pressure dominates compression ratio and efficiency, rebound pressure mainly affects operating frequency, and injection width governs indicated work and peak pressure. This study establishes a coupled analysis framework, providing concrete insights for optimizing opposed-piston FPEG performance through parameter coordination.
Wu, Limin, Ji, Kaixuan, Feng, Huihua, Jia, Boru, Zuo, Zhengxing
Efficiency Modeling, Experimental Validation, and Machine Learning-Assisted Model Calibration of a Two-Speed E-Drive Transmission for Construction Equipment02-19-03-00197/27/2026
This study details the development and experimental validation of a high-fidelity one-dimensional (1D) simulation model for a two-speed transmission designed for off-road vehicles, such as tractors and backhoe loaders used in agricultural and civil engineering applications. The model, implemented in the AMESim platform from Siemens, integrates physics-based loss sub-models for all major components, including gears, bearings, seals, and fluid drag (churning) losses. After development, the model was rigorously validated against test bench data, with efficiency measurements taken across various speed, torque, and oil level combinations, demonstrating a strong correlation with experimental results. A detailed analysis enabled the quantification of the contribution of each loss mechanism, identifying the countershaft gears and input shaft bearings as the primary contributors. Furthermore, a Machine Learning (ML)–based calibration framework, employing Bayesian Optimization, was implemented to reduce discrepancies between simulation and experiment and to generate a synthetic dataset for the creation of fast-executing surrogate models. The study concludes that the proposed methodology constitutes an effective tool for efficiency analysis and optimization during early design stages, establishing a foundation for future integration with ML techniques and the development of digital twins.
Ferreira, Tiago Simao, Fallahi, Farzad, Kedziora, Slawomir, Hichri, Bassem, Kiefer, Jean-Daniel
3D Computational Fluid Dynamics Analysis of the Performance and Emissions of an Off-Highway Port Fuel Injection Hydrogen Engine03-19-04-00187/27/2026
To fulfil the global aspiration of achieving net-zero emissions, hydrogen as a fuel seems to be one of the promising candidates. High energy density per unit mass and zero carbonaceous emissions are the two salient advantages that hydrogen offers. In the present study, a set of detailed chemistry-based 3D CFD combustion simulation has been carried on a 3-cylinder turbocharged, water-cooled port fuel injection SI Hydrogen engine to understand its optimum air–fuel ratio, compression ratio, spark timing and combustion chamber geometry. The simulations have been conducted at the full load of the rated power and maximum torque engine rpms. During simulation, the λ zone for study is restricted between 2.1 and 2.7. Two different bowl geometries (spherical and cylindrical), with two compression ratio options (12 and 14) are explored in the simulations. While the spherical bowl seems to accommodate flame front better than the cylindrical bowl, the compression ratio of 12 is a safer choice to control the maximum rate of pressure rise (dp/dθ). At full load and rated speed, the indicated thermal efficiency drops by 7.7% as the λ swings from 2.1 to 2.7, whereas the indicated specific NOx and dp/dθ drop by 99% and 81%, respectively. Similarly, at full load and maximum torque RPM, the indicated thermal efficiency drops by 6.4% with λ swing from 2.1 to 2.7, whereas the indicated specific NOx and dp/dθ drop by 99% and 91%, respectively. Beyond λ = 2.4 NOx reaches almost to zero, however, at a compromise of the thermal efficiency. The dp/dθ remains well within the acceptable limit under this scenario. To account this trade-off between the performance and emission parameters, optimum λ zone has been found out to be between 2.3 and 2.5.
Satre, Santosh Dadasaheb, Mukherjee, Nalini Kanta, Kumar, Sanjeev, Nene, Devendra
An Updated Data-Driven Greenhouse Gas Emission Rate Analysis for Vehicle Comparisons Applied to Europe14-15-03-00167/25/2026
This study presents a data-driven lifecycle assessment (LCA) framework for evaluating greenhouse gas (GHG) emissions from passenger vehicles across European electricity systems. The analysis compares battery electric vehicles (BEVs), full hybrid electric vehicles (FHEVs), and internal combustion engine vehicles (ICEVs) using both conventional average electricity emissions factors and time-resolved marginal emissions, referred to as real charging emissions (RCE). Hourly generation and interconnector/cross-border flow data for 2023 from 29 European countries are processed to estimate consumption-based marginal emissions rates that account for grid dispatch behavior and cross-border electricity flows. The approach is applied to two vehicles where multiple powertrains are available on the same platform, the 2024 Hyundai Kona (available as a BEV, FHEV, and ICEV) and Peugeot 2008 (available as a BEV and ICEV), to isolate drivetrain-related lifecycle differences. Results show substantial divergence between average and marginal emissions estimates, with a mean absolute difference in BEV–FHEV lifecycle emissions of 31–36 g CO2 eq/km across Europe. In several countries with carbon-intensive marginal generation, including Poland and Cyprus, BEVs may exhibit higher lifecycle emissions than comparable hybrids, while low-carbon grids such as Norway, Sweden, and France provide large BEV advantages. Sensitivity analyses demonstrate the importance of transmission losses, temperature effects, electricity imports, and charging timing. These findings highlight the limitations of average grid emissions factors in vehicle LCAs and underscore the importance of geographically and temporally resolved data-driven electricity emissions when assessing electrified vehicle climate impacts.
Drew, Alfred, Burton, Tristan, Senecal, Kelly, Davy, Martin, Leach, Felix
Analysis of the Cause of Knocking Noise in a Marine Dual-Power Dual-Branch Transmission Gear System2026-99-16507/24/2026
This study investigates the knocking noise phenomenon in a marine dual-power dual-branch transmission gear system. Vibration mechanisms are analyzed, and potential failure modes are assessed. System vibration data were evaluated using time-domain and frequency-domain methods. Results show that overall vibration levels remained within acceptable limits, with no indication of imminent failure. Physical inspection confirmed that the shaft, gears, bearings, housing, and installation met specifications, with no observed performance degradation or structural damage. By correlating noise occurrence with vessel loading conditions, a strong relationship was identified among gear transmission torque, the power distribution ratio between high-and low-pressure turbines, and the onset of knocking. Specifically, under low-load conditions, uneven power and torque distribution among the four gear branches led to insufficient loading on the low-pressure side. This light-load state induced instability in the low-pressure gears, resulting in periodic tooth disengagement or back-side tooth contact, which is established as the root cause of the knocking noise.
Gu, Chengzhong, Xu, Hanwei, Luo, Rirong, Ren, Fushan
Research on a Rocket Projectile Impact Point Prediction Model Based on Improved Proportional Navigation Guidance Law2026-99-16027/24/2026
Rocket projectiles are a type of ammunition that get their power from rocket engines. Long-range guided rockets, in particular, hold great significance as they seem to mark the way forward in modern warfare. These guided projectiles take full advantage of the considerable range that long-range rockets offer and, at the same time, manage to achieve improved accuracy. This paper delves into a model that is used for predicting the impact point of rocket projectiles, with the application of the proportional navigation guidance law. It also undertakes an analysis of both the strengths and the weaknesses of this model. Through the formulation of equations related to the dynamics of the center of mass and some other supplementary equations, a rather comprehensive trajectory equation was worked out. When this trajectory was simulated, it brought about the creation of a firing table, which is of help in predicting the initial trajectory inclination angle.
Tao, Wenwen, Wang, Ru, Zhang, Liang, Pi, Runge
Research on the Inter-Stage Energy Transfer System of Launch Vehicles Based on Multi-Channel Coupling Mechanisms2026-99-16197/24/2026
In the paper, a novel non-contact high-power energy transfer system based on a layered coupling structure is designed to meet the demand for reliable energy transmission during the inter-stage separation process of launch vehicles. The system adopts the upper four-coil transmitting array and the lower single-coil receiving structure and combines the innovative design of a 6:1 step-down transformer topology. Through the optimization of the multi-channel magnetic field coupling mechanism, the system realizes the safe transmission of more than 2 kW of power in close interstage under the difficult problem of transmission loss under the scenario of low input voltage and high output current, which effectively solves the problem of the system. Experimental findings can demonstrate that with a specified input voltage, the system could keep its output voltage of about 28 V under a given input voltage, and the maximum output current reaches about 85 A. The transmission efficiency is significantly higher than the traditional single-coil structure, and the measured data verify the applicability of the scheme in the core indexes of voltage stability, power capacity, and transmission distance. The design breaks through the reliability limitation of traditional contact connections under extreme working conditions and provides an innovative solution for continuous energy supply during the dynamic separation process of the carrier.
Guo, Xinwen, Jing, Xiaorong, Xu, Pengfei
Modeling and Simulation Analysis of Liquid Hydrogen and Power Systems Based on Amesim2026-99-16087/24/2026
Hydrogen-powered aircraft primarily utilize the conversion of liquid hydrogen into gaseous hydrogen to replace aviation kerosene, where hydrogen is directly combusted to provide propulsion. This study applied Amesim software to establish a complicated model simulating the liquid hydrogen to gaseous hydrogen conversion and ignition combustion processes. The simulation contains converting liquid hydrogen into gaseous hydrogen through a heat exchanger and simulating the mixture of gaseous hydrogen and air in the engine combustion chamber, and then igniting the mixture. The pressure, temperature, and flow rate of gaseous hydrogen and air during the ignition and combustion process in the engine combustion chamber, as well as the outlet temperature of the combustion chamber, are simulated and analyzed. The results demonstrate that during the simulation process, the internal pressure of the liquid hydrogen storage tank, the outlet pressure and flow rate of the liquid hydrogen pump, and the pressure and flow rate of gaseous hydrogen meet the requirements of the ignition combustion test. In addition, varying gaseous hydrogen flow rates had significant impacts on the temperature of the combustion chamber during combustion.
Gao, Pengfei, Wang, Lijian
2025 International Conference on Solid Mechanics and Materials2026-99-16007/24/2026
TOC
Tobolski, Sue
Fatigue Life Analysis of Diesel Engine Filter Seat under Random Vibration Condition2026-99-16567/24/2026
The filter seat of diesel engine fuel filters is a key load-bearing component in the engine fuel system. Its structural integrity directly affects the reliability and safety of fuel delivery. In actual operation, the filter seat is subjected to random vibration loads generated by engine operation and vehicle dynamics, which may cause fatigue failure over time, even when static stresses are below the yield strength. This study employs finite element modeling (FEM) to investigate the structural strength and fatigue life of the diesel engine filter seat under random vibration conditions. The CAD model is simplified and meshed to reflect the main load paths, and boundary conditions, including bolt preload, gravity, and measured vibration PSD spectra are applied. Modal and harmonic response analyses are performed using Abaqus, and the Tovo-Benasciutti frequency-domain method is used in fe-safe to predict fatigue life. The results identify the most fatigue-sensitive areas and reveal that the minimum fatigue life is 10^3.067 cycles under realistic conditions, with the most critical regions located near the bolt connection. The simulation methodology and results provide a reliable basis for structural optimization and life prediction of similar components under random vibration environments.
Gu, Kexuan, Zhu, Yi, Xie, Liang, Wang, Wei
Design and Dynamic Simulation of a High-Speed Conjugate Parallel Indexing Cam Mechanism2026-99-16257/24/2026
The cam mechanism, as an extremely important transmission method in mechanical transmission, is widely used in automatic machinery and automatic control devices. In small and medium-sized high-speed automatic guns, high-speed camshafts are often used to achieve intermittent movement of the supply and transport of ammunition during high-speed shooting. Due to the possible vibrations, wear, and instability that may occur during the movement of high-speed camshafts, the design of camshafts needs to meet the requirements of continuous third-order derivatives of the curve, while minimizing angular acceleration as much as possible. This article focuses on the design requirements of a high-speed intermittent motion mechanism, with continuous angular velocity and angular acceleration as design constraints. It establishes segmented function motion equations for the acceleration, deceleration, and uniform speed sections of a high-speed conjugate parallel indexing cam while ensuring that the design cam curve does not have knots. The theoretical profile and the actual profile of the cam, considering roller radius offset, are calculated. Based on this, dynamic simulations are carried out on the acceleration and deceleration sections of the cam roller, and the structural response considering structural elastic deformation and contact collision conditions is obtained. The calculations show that the cam and roller meet the structural strength requirements during high-speed motion. Experimental verification shows that the structure is stable and reliable during high-speed motion.
Wang, Shuman, Qin, Yanhui, Ning, Bianfang
Alignment Control of an Aerial Wireless Power Transmission Device2026-99-16227/24/2026
With the development of battery technology and wireless power transmission technology, their applications in the aviation field have broad prospects. Alignment control is the key to achieving wireless power transmission in the air. This paper first establishes a mathematical model for the proposed wireless power transmission device, decomposes and simplifies it to obtain a controlled object model that is more suitable for the algorithm in this paper. Aiming at the accuracy of alignment control in the task, a fused dynamic inverse algorithm with feedforward optimization was designed step by step and verified through simulation. In the simulation, typical application scenarios were designed in combination with the requirements of wireless power transmission technology. The results show that compared with the general dynamic inversion algorithm and differential feedback-fused dynamic inverse algorithm, better alignment control effects have been achieved, and this algorithm can achieve alignment within the expected error range, further verifying its effectiveness and having certain application prospects.
Tan, Xudong, Hei, Wenjing, Lei, Yidi
Design and Application of A Pressure Measurement System Based on Spacecraft Chemical Propellant Engine Plume Test2026-99-16237/24/2026
Spacecraft with chemical propellant engines, especially spacecraft for exploring extraterrestrial objects, need to carry out plume tests on the ground in order to determine the influence of engine plumes on spacecraft. An important purpose of the plume test is to accurately measure the pressure field in key parts of the spacecraft. In this paper, according to the pressure measurement requirements of the spacecraft plume test, the design of a pressure measurement system is carried out, which mainly includes a pressure measurement sensor, a pressure difference measurement sensor, a pipeline, a cable, a measuring instrument, a data acquisition instrument, upper measurement software, and so on. The designed pressure measurement system was successfully applied to the plume impact test of Chang'e VII, which provided important technical support for the development of the spacecraft.
Wu, Yue, Guo, Qinliang, Wu, Dongliang, Liu, Xiaoning, Tao, Dongxing, Lin, Boying, Xie, Zheng, Wei, Xi, Niu, Tong
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