Browse Topic: Bodies and Structures

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Measurement and Regulation of Residual Stress in Door Opening Welds of Wind Turbine Towers2026-99-01977/31/2026
Weld residual stress is a critical factor affecting the structural integrity and service life of wind turbine towers. In this study, a systematic investigation was conducted on the residual stress distribution and control methods for door corner welds of an in-service wind turbine tower after approximately 20,000 hours of operation. X-ray diffraction (XRD) measurements revealed significant tensile residual stress in the weld and heat-affected zone, with peak values reaching 315 MPa, particularly concentrated at depths of 5-7 mm. To mitigate these stresses, two post-weld treatment methods were employed: ultrasonic impact treatment (UIT) and localized heat treatment. UIT effectively transformed surface tensile stress into compressive stress, achieving a maximum compressive residual stress of -372 MPa within a depth of 3 mm, while simultaneously refining grains and increasing surface hardness. In contrast, localized heat treatment at 460 °C for 5 hours led to a broader stress relief effect, reducing residual stress by approximately 100 MPa without causing significant changes to the macrostructure, but inducing substructural rearrangements beneficial for stress relaxation. Mechanical testing confirmed that both treatments improved tensile strength, ductility, and toughness of the welds. The combined findings demonstrate that ultrasonic impact treatment is highly effective for enhancing fatigue performance at the surface, while localized heat treatment offers advantages for deep stress redistribution and long-term structural stability. This comprehensive approach provides valuable technical guidance for residual stress management in complex welded structures of wind turbine towers.
Sun, Wanting, Zhong, Zhenqian, Zhang, Bo, Liu, Hui
Design and Optimization of an External Rotor Permanent Magnet Motor with a Three-Segment Non-Uniform Halbach Array2026-99-01537/31/2026
To further enhance the performance of the drive unit motor, a novel three-segment non-uniform Halbach array magnetic pole structure is proposed, which is applied to an external rotor permanent magnet motor with magnetic pole optimization. First, the overall motor design is carried out according to the requirements, determining the fundamental parameters of the motor. Then, four common magnetic pole structures—conventional arc-shaped, three-segment, Halbach array, and three-segment non-uniform Halbach array—are analyzed. A finite element analysis model of the motor is established for electromagnetic analysis, comparing the air-gap flux density, torque, and torque ripple of the four magnetic pole structures. Finally, optimized parameters for the stator and rotor tooth shapes are determined, and an optimization model is established. The NSGA-II algorithm is employed to optimize the stator and rotor tooth shapes. After optimization, the motor maintains its torque output while reducing torque ripple by 50%, effectively improving its performance.
Zhao, Changle, Yang, Liu
The Influence of Stator Vane Lean on the Rotor Blade Forced Response of an Axial Turbine2026-99-02107/31/2026
Forced response resulting from rotor-stator interaction is a primary cause of high-cycle fatigue (HCF) failure in axial turbine blades. To investigate the mitigating effect of stator vane lean on the forced response of a downstream rotor blade, this paper conducts a numerical analysis based on a fluid-structure interaction (FSI) method, comparing a baseline radial vane with a leaned vane configuration in a single-stage axial turbine. Unsteady computational fluid dynamics (CFD) was used to analyze the unsteady flow field and aerodynamic excitation, and the resulting harmonic pressures were applied to a finite element (FE) model for harmonic response analysis. The results show that, compared to the radial vane, the leaned vane design effectively weakens the potential field and wake interactions by introducing a spanwise phase difference, which significantly reduces the amplitude of the unsteady pressure fluctuations. The harmonic response analysis further validates the effectiveness of this approach, demonstrating that under the first harmonic excitation, the leaned vane configuration reduces the maximum dynamic stress on the rotor blades by 37.7%. This study confirms that stator vane lean is an effective aerodynamic detuning strategy that mitigates the excitation at its source, leading to a substantial reduction in the rotor’s dynamic stress and thus offering a valuable method for improving turbine blade reliability.
Huang, Zhi, Zhang, Ying, Xiong, Zhonggang
Multi-Objective Topology Optimization of Wing Rib Structures for Additive Manufacturing2026-99-02287/31/2026
With the advance of high-end manufacturing and the rise of green design, lightweight structures have become a central concern in aerospace. Topology optimization offers a principled route to shed mass while preserving performance, yet most additive manufacturing (AM) studies still emphasize process tuning and new materials rather than structural layouts constrained by AM realities. This work targets a representative wing rib from a specific unmanned aerial vehicle (UAV) and formulates a multi-objective topology optimization that explicitly embeds AM constraints. Using the Solid Isotropic Material with Penalization (SIMP) variable-density framework, we couple static stiffness and strength measures with modal objectives so that the optimized rib not only resists deformation and limits stress but also improves the first three natural frequencies, thereby mitigating adverse vibration interactions at the wing level. A compromise-programming strategy balances these competing objectives under volume and manufacturability requirements, including AM-driven minimum feature scales and related geometric restrictions. Finite-element analyses are used throughout the loop to evaluate displacement, von Mises stress, and eigenfrequencies, ensuring that the emerging material distribution is both efficient and physically meaningful. The resulting topology exhibits clearer load paths and smoother stress flow, reduces peak displacements, and delivers a marked rise in the first three natural frequencies. Overall mass is lowered by approximately 55% while meeting all imposed constraints, achieving the dual aims of structural optimization and lightweighting. The study demonstrates that integrating AM constraints directly into the optimization stage yields designs that are performance-robust and fabrication-ready, and it provides a reusable workflow for thin-walled aerospace components such as wing ribs where stiffness, strength, and vibration behavior must be jointly considered.
Zhao, Fei, Zhang, Heran, Li, Xiaoting, Shi, Bowen, Kong, Xiangwei
Implementation Strategies of Requirements Engineering in Commercial Aircraft Airframe Forward Design2026-99-01837/31/2026
Focusing on the requirements engineering activities, this study analyzed the problems in the implementation process of the forward design practice of commercial aircraft airframe, introduced the breakthrough methods, including the convergence and integration with the traditional design process, the supporting work organization model, process optimization, and specification, and proposed the airframe stakeholder need capture model based on the theory of systems engineering. Practice has shown that the requirements engineering implementation strategy introduced in this paper can effectively resolve conflicts and redundancies between the requirements system and the original top-level document system requirements. It ensures clear requirements sources, sufficient basis, reasonable allocation, controllable changes, adequate change assessments, clear design status, and controllable design risks. It effectively overcomes human resource bottlenecks during the early stage of requirements engineering implementation while cultivating talent reserves for systems engineering implementation, saving approximately 23.5 person-years in labor costs. It significantly optimizes non-value-added processes, reducing approximately 100 reports. It unifies the team’s understanding of requirements work, improves coordination efficiency, and significantly improves the requirements validation rate between aircraft-level and system-level requirements by an average of approximately 46%. It assists stakeholders and engineers in systematically and scientifically capturing product requirements during the design phase, with original product design specifications covering approximately 70% of subsystem specifications on average. Given its generality across the airframe forward design domain, the airframe requirement management paradigm established by this implementation strategy holds significant importance for the comprehensive and in-depth application of systems engineering methods in commercial aircraft development.
Sun, Luyan, Chang, Liang
Study on Energy-related Mechanisms of Aeroelastic Instability of Ultra-Long Flexible Wind Turbine Blades Under Various Working Conditions2026-99-01347/31/2026
With the continuous increase in wind turbine power capacity, ultra-long flexible blades face intensified aeroelastic instability risks due to reduced structural stiffness, enhanced modal coupling, and aerodynamic nonlinearity. In addition to the analysis of basic vibration characteristics, this study focuses on energy-related mechanisms of aeroelastic instability under various working conditions. Using a numerical model integrating Dynamic Blade Element Momentum Theory (DBEMT) and Geometrically Exact Beam Theory (GEBT), over 400 time-domain simulations were conducted to characterize instability onset and development. Results reveal four distinct aeroelastic instability regions, each dominated by specific modes. In Region A, flutter dominated by the 2nd flapwise mode is observed. In Region B, flutter dominated by the 1st edgewise mode is observed. In Region C, flutter dominated by the 2nd edgewise mode is observed. While in Region D, where the medial angle of attack (AoA) of the blade has exceeded the stall angle, stall-induced vibration dominated by the 1st flapwise mode is observed. Energy analysis shows aerodynamic work concentration near the blade tip drives instability, with diverse energy exchange patterns across regions. Except for some operating conditions in region C, where instability is dominated by edgewise energy absorption, most aeroelastic instability conditions are dominated by flapwise energy absorption. Torsional degree of freedom contributes minimally to aerodynamic work, but the torsional vibration exerts a notable influence on the AoA. This, in turn, changes the comprehensive aerodynamic forces impacting the blade as well as the general aeroelastic stability. This study clarifies the relationship between operating conditions and energy-driven instability, offering some reference values for the design work and safety assurance of ultra-long flexible blades of the wind turbine.
Wang, Su, Chen, Jiajia, Zhou, Le, Shen, Xin, Li, Chun, Du, Zhaohui
Research on Failure Analysis of Aircraft Windshield Outer Layer Fracture Caused by Arc Fault2026-99-01287/31/2026
The malfunction of the aircraft windshield electric heating system, particularly arc discharge, poses a serious threat to flight safety by causing glass breakage. A systematic study was conducted on the causes and effects of arc faults on windshield structural integrity, employing macroscopic observation, microscopic analysis, and energy dispersive spectroscopy (EDS) following a windshield fracture incident. The results indicate that arc discharge typically occurs at the interface between the heating film busbar and adjacent structures. Localized high temperatures cause the outer glass to fracture, generating radial cracks. The ablation of the busbar silver coating and the carbonization of the PVB interlayer are direct evidence of arc action, whereas the heating wire remains a passive component affected by the high-temperature environment. The fault is primarily attributed to local disbonding at the busbar interface and moisture ingress. Based on the findings, recommendations are proposed for process optimization and inspection method improvement, providing a basis for the safe design and maintenance of windshield structures.
Chen, Li, Feng, Yanpeng, Ding, Keqin
Simulation of Compression and Bending Performance of GFRP Rod of Composite Hollow Post Insulator2026-99-01077/31/2026
Composite hollow core station post insulators utilize fiber-reinforced epoxy resin as the core rod material, offering advantages such as high specific strength, high specific stiffness, and excellent fatigue resistance. This enables them to effectively meet the flexible, variable, and complex operational demands of modern power systems. However, composite materials exhibit anisotropic characteristics, resulting in complex mechanical properties. Additionally, the core rod of hollow pillar composite insulators is typically fabricated through a spiral-plus-circumferential winding process, which significantly complicates structural design and computational analysis. This study establishes a finite element model of the hollow pillar composite insulator core rod in ABAQUS. It analyzes the influence of fiber content on composite material parameters and performs finite element numerical calculations to examine the stress state of core rods with different winding angles under compressive and bending loads. The research findings provide theoretical support for the optimized structural design of hollow pillar composite insulator core rods.
Liu, Jianbiao, Du, Yijun, Quan, Xiaoxi, Zhou, Songsong
Analytical Analysis of Wellbore Stresses under Fluid Pressure and In-Situ Stress in Three-Dimensional Wellbores2026-99-08317/30/2026
During fluid injection operations such as fracturing and well killing, the casing, cement sheath, and borehole wall rock are subjected to three-dimensional in-situ stresses and internal pressure. If the equivalent stress exceeds the material’s yield strength, component failure may occur, leading to wellbore failure or even blowout accidents. In order to investigate the stress distribution in wellbores under specific working conditions, a three-dimensional mechanical model of curved wellbores was established. By adopting the superposition principle and stress function method, the influence of horizontal in-situ stress non-uniformity on the fourth equivalent stress of various components was analyzed. The study demonstrates that under three-dimensional in-situ stress, the fourth equivalent stress of each component increases with the rise of horizontal in-situ stress load non-uniformity and azimuth angle. Meanwhile, borehole azimuth angle and in-situ stress load non-uniformity exert a greater influence on the fourth equivalent stress of the casing, while internal pressure has a lesser impact on it. The effects of azimuth angle, horizontal in-situ stress load non-uniformity, and internal pressure on the fourth equivalent stress of the casing are more significant than those on the cement sheath and borehole wall rock. The research results can provide theoretical and technical references for wellbore design and safety improvement, as well as for the structural safety assessment of components such as automotive chassis and body frames under complex dynamic loads.
Zhang, Wenzhe, Jiang, Wu, Guo, Ziwang, Cao, Yinping, Dou, Yihua
Research on the Design Technology of Anti-Roll Attachment for Seaplanes2026-99-08037/30/2026
This paper takes a seaplane as the research object, based on the roll damping commonly used in the field of ships, to carry out the applicability analysis and design technology research of the roll damping for the seaplane. A T-tail configuration was selected as the attachment. The design process involved sequentially selecting the horizontal stabilizer airfoil, designing the aspect ratio parameters, and determining the strut airfoil. Consequently, two T-tail design schemes with aspect ratios of 0.76 and 1.53 were proposed. Through the hydrodynamic performance analysis of the T-tail design installed on the seaplane, the advantages and disadvantages of the two T-tail designs in the wave environment are studied. The results demonstrate that the aspect ratio of the T-tail’s horizontal stabilizer directly affects the seaplane’s wave-induced motion response. The proposed design with a larger aspect ratio of 1.53 significantly reduces wave resistance and motion response across various conditions. In the case of a relatively small aspect ratio, the maximum pitching motion is reduced by 38.4%, and the maximum heave is reduced by 59%.
Jiang, Ting, Pi, Xufeng, He, Chao, Wen, Changqing, Li, Xu
Analysis of Underbody Impact Scenarios in New Energy Vehicles2026-99-08277/30/2026
In recent years, with the rapid increase in the market penetration of new energy vehicles, safety issues in electric vehicles, particularly those characterized by thermal runaway of power batteries, especially fire incidents caused by mechanical abuse from underbody impacts, have become a major focus of industry attention and social concern. This paper systematically compiles key data from electric vehicle underbody collision incidents, covering core parameters such as impact location, geometric features of obstacles (shape and size), and vehicle speed during accidents. Based on this data, the study further reviews existing underbody scraping evaluation protocols both domestically and internationally, with a focused comparison of the differences in mechanical load and battery pack response between two typical test methods: horizontal underbody scraping and 3° inclined underbody scraping. The findings of this research aim to provide data support for the refinement of relevant evaluation standards and to offer theoretical foundations and practical references for automotive manufacturers in optimizing the design and validation strategies for underbody protection of battery packs.
Wang, Qinggui, He, Qike, Li, Wenbo, Li, Chun, Li, Xiaodong
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
A Standardized Mid-Fidelity Aerodynamic Comparison of Four Tiltrotor eVTOL Configurations Using SUAVE and VSPAero2026-99-08397/30/2026
This study compares 4 representative tiltrotor platforms: Joby S4, Archer Midnight, Vertical Aerospace VX4, and Uber eCRM-001 in a typical UAM mission profile under standardized rotor and wing assumptions using an integrated OpenVSP-SUAVE-VSPAero framework. This work aims to isolate the influence of eVTOL configuration from proprietary optimizations on thrust generation and aerodynamic interaction by using standard wing airfoils and a consistent rotor design tool. Vehicle geometries were modeled in OpenVSP. Rotor Operating conditions were obtained from the SUAVE conceptual design platform. Mid-fidelity aerodynamic analysis was done using VSPAero. SUAVE results show a decrease in thrust requirements as the tilt angle decreases, with the most complexity occurring in the transition phase where lift shifts from rotors to wing. Archer Midnight and Vertical Aerospace VX4 show higher hover thrust requirements due to their high takeoff weights. They display localized thrust increase near mid transition due to numerical adjustments made to achieve solver convergence. Joby S4 and Uber eCRM-001 display a smoother thrust requirement trend. VSPAero simulations also show a gradual decrease in thrust from hover to cruise. Joby S4’s continuously active rotor configuration maintained more stable performance than the hybrid configurations, which deactivate lift-only rotors after takeoff. A comparative flight feasibility analysis was conducted, defined as the difference between VSPAero-predicted thrust and SUAVE-required thrust. This analysis reveals that Joby S4 maintains a positive margin across most flight phases. Archer Midnight and Vertical Aerospace VX4 show a marginal deficit in near-cruise phases. Uber eCRM-001 showed negative margins throughout the mission, indicating limited aerodynamic robustness under standardized assumptions. Rotor-wing interactions enhances rotor thrust across all mission segments, while creating periodic pressure oscillations on the wings. Rotor-rotor interactions provide limited near-field benefits that dissipate in forward flight. The findings of this study highlight the significance of eVTOL configuration in determining performance and aerodynamic efficiency.
Sawron, Md Sadat Shahrier
Adaptive Attitude Adjustment Mountain Transport Vehicle for Electric Tower Material2026-99-08507/30/2026
Transporting large steel materials for mountain electric towers is challenging due to steep gradients, narrow roadways, and uneven terrain. To address these issues, this study designs an adaptive attitude adjustment mountain transport vehicle. This mountain transport vehicle has a compact structure, measuring 1.4 meters in length and 1.1 meters in width, which enhances its suitability for confined mountainous environments. This vehicle adopts a design scheme that combines hydraulic lateral adjustment, load-bearing platform follow-up adjustment and frame adaptive adjustment mechanisms. The transportation of tower materials, measuring 12 meters in length and 1.2 tons in weight, is accomplished by employing two vehicles working in coordination. The three-dimensional model of the entire vehicle is established by using SolidWorks software. The lateral stability of the mountain vehicle and the limit working conditions of its adjustment mechanism are analyzed through theoretical calculation. The dynamic simulation of the virtual prototype is carried out using Adams software, including the processes of lateral leveling, follow-up adjustment and frame adjustment. The results show that the leveling mechanism can achieve an adjustment range of more than ±25°. The results confirm the vehicle’s excellent stability and adaptability to mountainous conditions. This study provides a more effective and more reliable solution for the construction of mountain electric towers than traditional manual or animal-powered transportation methods.
Zhang, Rui, Kong, Fanfang, He, Yuling, Lv, Jiahui, Chen, Changlong, Zhan, Lulin, Liang, Ke
Design of a Jamming Test Apparatus for Aircraft Cargo Door Latches2026-99-08337/30/2026
The reliability verification of cargo door latches for civil aircraft requires a safe, accurate, and controlled method for simulating jamming failures in lab settings. We adopt a crank-rocker mechanism with a variable degree of freedom (DOF) to construct a novel jamming apparatus that may be dynamically constrained in order to meet this requirement. The apparatus maintains two DOFs when not in use, which permits the latch mechanism to move freely. Both the guiding shafts and the rotation shafts are simultaneously constrained for a jamming test, reducing the mechanism’s DOFs to zero. This operation creates a precise and passive lock that immobilizes the mechanism without the need for an active external load. This approach offers a more realistic simulation of the sudden jamming brought on by wear, foreign object intrusion, or manufacturing tolerances. A theoretical kinematic analysis is then conducted to calculate the mobility of the mechanism and determine the theoretical conditions and transition paths to reach the two functional states. Moreover, the apparatus implements a real-time computational model based on classical planar linkage force analysis and integrates a multi-sensor system. This model converts sensor data into the torques and jamming forces that are actually delivered to the latch. The findings demonstrate that the proposed design accurately simulates latch jamming conditions while allowing for real-time monitoring and quantification of important dynamic characteristics. Thus, by offering a dependable and effective verification solution for cargo door latches, the apparatus greatly improves testing safety and the value of the data gathered.
Ren, Jie, Zeng, Xiaohu, Qiu, Xudong, Xie, Youshui
Research on a Lightweight Door Based on an Approximate Model Constructed by a Differentiation Strategy2026-99-08127/30/2026
Taking the front door of a new energy vehicle as the research object, a finite element model was built based on HyperMesh to conduct stiffness and modal performance analysis, and clarify the characteristic differences of multiple responses of the door. To address the issue that traditional single approximation models are difficult to adapt to different response characteristics, a strategy for constructing differentiated approximation models is proposed, which is to select the optimal approximation model according to different response types. The results show that the approximation models for each response constructed based on the differentiation strategy have a fitting accuracy (R^2) of more than 0.99, close to complete fitting, which is significantly better than the overall adaptation effect of a single model. Finally, based on the approximate model established using this strategy, combined with a multi-objective optimization algorithm, the dimensions of the front door are optimized, while achieving lightweighting and performance improvement of the front door, which provides a new idea for constructing multi-response high-precision approximate models.
Wei, Yansai, Shen, Yongfeng
Analysis of the Hot Forming Behavior of AZ91 Magnesium Alloy2026-99-08387/30/2026
This study systematically discussed the high-temperature flow behavior of the Mg-Al-Zn based AZ91 alloy, which has significant application potential in modern aviation and automotive industries. The study was carried out in the temperature range of 250°C-450°C and the strain rate range of 0.001 s^−1 -0.1 s^−1, which met the typical industrial hot processing environment. The analysis of high-temperature flow behavior shows that the flow stress is inversely proportional to the deformation temperature and is proportional to the strain rate. An important finding is that the constitutive model parameters are significantly sensitive to strain, so the strain-compensated Arrhenius constitutive model is developed. The model shows high accuracy in predicting the thermal flow stress of AZ91, and provides a valuable calculation tool for the simulation and optimization of forming processes in aerospace parts manufacturing. The results show that the extruded original microstructure presents slender fine grains, while the deformed sample shows a temperature dependent transformation: the low-temperature bimodal structure evolves into uniform fine grains at intermediate temperature, and the grains begin to coarsen at high temperature. At constant high temperature, low strain rate promotes grain growth and twin formation, while high strain rate refines grains and inhibits twins, and dislocation slip is the dominant deformation mechanism. These findings provide vital guidance and support for optimizing hot working parameters of AZ91, and are particularly important for manufacturing lightweight components in aircraft structures and automotive systems. The established process performance relationship is helpful to develop energy-saving manufacturing strategies for transportation equipment, and supports the goal of reducing weight and improving performance in the industrial field.
Li, Jusen, Chang, Ming, Zhu, Wenyu, Sun, Haoran, Chen, Kaida, Yang, Xiaoyin, Zheng, Zhenhao, Zhao, Shengdun
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
Systematic Assessment of State-of-the-Art Approaches Available for Variable Camber Morphing01-19-01-00057/29/2026
Aerodynamicists around the globe are developing mechanisms and structures inspired by nature that enable variable camber morphing (VCM) for aerodynamic surfaces. The implementation of the VCM mechanism in an airplane wing enhances the performance and stability during various flight segments. The present review article is focused mainly on the up-to-date VCM methods in a qualitative as well as quantitative approach that are specific to Aircraft/unmanned aerial vehicle (UAV) wing configurations. Initial literature discussions are confined to the conventional mechanisms that enable VCM in different aircraft configurations and the added aerodynamic advantages such as lift enhancement, drag reduction, boundary layer separation, and flow control. However, those designs need either external shape optimization or internal structural refinements to ensure the factor of safety (FoS). The modern aviation industry is also focused on bioinspired technology because of the adaptive flying capabilities and stall-delay characteristics. Therefore, a review of bioinspired VCM methods that are assessed based on the aerodynamic potentials is sequentially organized in the article. Additionally, considerations are motivated by the application of various compliant structural patterns for VCM in the aircraft industry. The discussion indicates the prospective benefits of morphing toward the future of the Green Aviation industry.
Manjunath, S. V., Jini Raj, R.
Landing Gear Structural Health MonitoringAIR6168A (Current)7/27/2026
This SAE Aerospace Information Report (AIR) discusses past and present approaches for monitoring the landing gear structure and shock absorber (servicing), opportunities for corrosion detection, methods for transient overload detection, techniques for measuring the forces seen by the landing gear structure, and methods for determining the fatigue state of the landing gear structure. Landing gear tire condition and tire pressure monitoring are detailed in ARP6225, AIR4830, and ARP6137, respectively. Aircraft Brake Temperature Monitoring Systems (BTMS) are detailed in AS1145.
A-5 Aerospace Landing Gear Systems Committee
Geometric Deep Learning–Based AI Framework for Nonlinear Crash Behavior of Extruded Rails15-19-03-00127/27/2026
Extruded Rails are critical energy-absorbing components in automotive structures designed to mitigate impact loads during the frontal collisions. Traditional crashworthiness design relies heavily on computationally expensive finite element simulations and iterative design exploration. This work proposes a machine learning–driven framework for rapid front extruded rails design using a trained geometric deep surrogate model. A design-of-experiments (DoE) was conducted by varying geometric parameters including width, height, and wall thickness of a thin-walled extruded rail structure. For each design variant, LS-DYNA simulations were performed to obtain performance metrics such as mean crush force and peak crush force. These simulation results were used to train an AI surrogate model capable of predicting crash responses directly from geometric parameters. The proposed approach significantly reduces computational cost by replacing repeated high-fidelity crash simulations with machine learning surrogate predictions. By enabling fast and accurate evaluation of crash response metrics, the workflow shortens design cycles and supports sustainability-driven crashworthiness assessment by reducing simulation resource usage. The framework establishes a scalable, simulation-driven engineering pathway across vehicle platforms and provides a foundation for future closed-loop, AI-assisted crash design workflows.
Kumar, Manik, Srinivasan, Sriram
Research and Application of Flush Adjustment for Multi-Link Retractable Hatch2026-99-16207/24/2026
The adjustment process for multi-link retractable hatches has long relied on personal experience, making it difficult to achieve precise and quantitative length adjustments. This limitation has consistently constrained the efficiency of the adjustment process. This paper aims to analyze the risks and shortcomings in the existing flush adjustment process, simplify the flush adjustment process into a mathematical model, and calculate the required adjustment amount of the actuator length. By simplifying the flush adjustment process and steps, the risk associated with the adjustment process can be reduced, and the efficiency of door step difference adjustment can be improved.
Deng, Qinwen, Shen, Yingdong, Wang, Zhihai, Li, Yixiao, Wei, Xingxu, Gao, Haosen
Accurate Control of Refueling Volume for a New Type of Oil Change Device in the Reducer of Tobacco Machinery Equipment2026-99-16187/24/2026
In order to achieve precise control of refueling volume, improve oil change efficiency, reduce oil pollution and waste, a new oil change device for the reducer of the range hood equipment is studied. We design a new oil change device that integrates oil discharge and refueling functions based on the operating characteristics of the reducer in the range hood equipment. Using the rotational speed of the power pump and the flow rate of the oil pipeline as variables, we determine the refueling flow rate using a one-dimensional quadratic formula. Based on direct control theory, we optimize the relative position parameters of each component of the device, establish a control matrix, and achieve precise control. The experimental results show that the new oil change device exhibits good performance during both one-time oil discharge and refueling processes, meeting the precise control standards for refueling volume. The design and application of a new oil change device can effectively improve the efficiency and accuracy of oil change in the reducer of the range hood equipment, and have practical application value.
He, Pengtao, Wei, Bo, Liang, Zhiyuan, Deng, Weiren, Liang, Wenbin, Xing, Yuquan
Research on the Application of Eddy Current Retarders in Aircraft Arresting Systems2026-99-16217/24/2026
At present, the aircraft arresting system in our country is the fixed water turbine type. This kind of equipment cannot achieve the arrestment of multiple aircraft types, and the arresting distance cannot be adjusted. According to these problems of the aircraft arresting system in our country, the eddy current retarding device is added, based on the water turbine braking device of the aircraft arresting system. It derives the differential equation for an aircraft arresting system with a water turbine brake and eddy current retarder using mathematical modeling. Four types of aircraft parameters are selected, and MATLAB is used as a simulation tool to verify the reliability of the arresting system after installing the eddy current retarder. This research can improve the arresting support ability and make the arresting device meet the arresting requirements of different types of aircraft.
Wei, Yan, Feng, Chunchun, Wang, Jianwu, Li, Binghong, Yang, Yang
Lightweight Optimization Design of Subframe Structure Based on Sensitivity Analysis2026-99-16397/24/2026
In order to meet the needs of national energy conservation and environmental protection policies, a typical chassis structure lightweight method based on sensitivity analysis of 13 strength conditions was proposed. Firstly, the finite element model of the subframe of a certain model is established, and the impact strength and static strength of the subframe structure are analyzed by the finite element method. Secondly, the sensitivity analysis of 13 strength conditions was carried out for the 12 main sheet thicknesses in the finite element model. Based on the results of the sensitivity analysis, the plate thickness of the components that is conducive to lightweight and has little impact on the 13 strength conditions of the subframe was selected as the design variable. The size optimization was carried out with the goal of minimizing the mass of the subframe and the constraint that the maximum Von Mises stress of the unit, where each material is located, did not exceed the yield strength of the material. The optimization results show that the performance of the subframe under 13 strength conditions meets the requirements of the index, and the weight of the subframe is reduced by 1.37 kg / 9.6%.
Jing, Min, Jia, Zhilong, Zhang, Hualei, Liu, Minjie, Gan, Xinhua, Gao, Jinyu
Integrated Guidance and Control Design Based on Sliding Mode Control Theory2026-99-16337/24/2026
In order to meet the demand for missile miniaturization and simplify the system complexity, this paper designs a guidance control integration method according to sliding mode control based on the longitudinal plane motion model, which is combined with the theory of sliding mode control. The design realizes tracing of attack angle to line-of-sight angle through sliding mode control of the outer loop, and the tracking of the control volume rudder deflection angle to the virtual control volume angle of attack through the sliding mode control of the inner loop. The stability of the guidance law is also verified by the Lyapunov function. The simulation results show that the guidance law can hit the target successfully, which verifies the feasibility and effectiveness of the design method.
Bai, Jiajun, Ming, Chao, An, Zhichao, Niu, Zhaoqi, Wen, Guangbao
Biomimetic Design and Numerical Analysis of a VIV Suppression Fairing for Offshore Risers2026-99-16407/24/2026
As oil and gas exploitation advances into deep seas, risers linking offshore platforms and subsea extraction systems endure long-term complex marine loads. Fatigue damage from Vortex-Induced Vibration (VIV) has become a key factor limiting the safe operation of deep-sea engineering structures. To address this issue, a bionic adaptive rotating fairing, which is adjustable to ocean current directions, was designed. Its main components include buoyancy blocks, a fairing with spiral guide rails on the inner wall, and clamps, which work together to reduce VIV by regulating flow patterns. Numerical simulations of concave and convex fairings showed that under subcritical flow, shifting from a concave to convex cross-section gradually enhances the fairing’s drag and lift reduction effects on risers, with a steady improvement trend. Further comparisons were made between 0.25D convex fairings, 0.35D convex fairings, and bare risers, focusing on drag/lift reduction, vortex shedding frequency, and Strouhal number. Both convex fairings exhibited similar VIV suppression performance to the bare riser, but differed significantly in the percentage reduction of vortex shedding frequency and Strouhal number. Thus, the 0.25D convex fairing was identified as the optimal configuration for VIV suppression among the concave-convex fairings studied.
Zhang, Xu, Song, Guangming, Wang, Baozhong, Zhao, Jinpeng, Chen, Qianshuo
Numerical Study of Structures for a Next-Generation Supersonic Transport2026-99-16267/24/2026
Because of the increasing requirement for frequent international traveling, developing a new generation of supersonic transport is critical for commercial aviation. The typical features of supersonic transport are a large swept-back wing and thin airfoil, potentially causing excessive tip deflection and triggering aeroelastic divergence. Hence, conducting evaluation, analysis, and optimization of the structures of an SST is essential. This study applied the finite element method to investigate the wing and fuselage structures under aerodynamic loads during cruise for a next-generation supersonic transport aircraft. Deformations and stress contributions were analyzed, showing the feasibility of the structure design and the stress concentration zones requiring reinforcement in the detailed design. Structural optimizations were also conducted, yielding significant weight reduction.
Ding, Menglong, Xu, Zhaoyang, Wang, Yongqiang, Meng, Li, Tan, Jiaxin, Xuan, Jinting, Bie, Dawei, Shao, Lintao
Study on the Aerodynamic Characteristics of Canard Configuration Missile Influenced by Aileron2026-99-16107/24/2026
The canard configuration has been widely adopted in short-range missiles. However, its main drawbacks include difficulties in roll control and a limited angle-of-attack (AoA) range. Compared to conventional canard missiles, the addition of a pair of control surfaces (referred to as “aileron”) behind the canard control surfaces achieves decoupling between the roll channel and pitch-yaw channel. To investigate the influence of ailerons on the aerodynamic characteristics of canard configuration missiles, numerical simulations were conducted for two typical flow conditions: subsonic (Mach 0.5) and supersonic (Mach2.0). The results show that the introduction of ailerons increases the normal force of missiles, causes the center of pressure to shift forward, and reduces the static stability of missiles, thus enhancing their maneuverability. When the ailerons control the roll channel, the effectiveness of the rolling moment remains consistent over the entire AoA range without adverse effects. However, when the canards control the pitch channel, the interference caused by the deflection of the canards on the ailerons leads to increased lift and generates additional nose-up pitching moments, which reduces the pitching moment effectiveness of the missile.
Zhang, Zilun, Xu, Jiasheng, Mei, Zhiwei
Load Analysis of Flap and Slat Actuators in Aircraft High-Lift Systems2026-99-18027/17/2026
This study develops an end-to-end load analysis scheme for flap and slat actuators, which comprise the aircraft’s high-lift system, and the analysis results are directly integrated into hardware optimization. Because they shoulder heavy responsibilities during the takeoff and landing phases, whether they can remain rock-solid under complex aerodynamic conditions or even remain unmoved in emergencies is directly related to their overall safety performance. This work process is closely linked and includes three major links. First of all, according to the CCAR-25.301 standard, the load envelope under normal working conditions is sorted out, and the limit cases of abnormal faults are exhausted. Subsequently, ANSYS Workbench pulled silk and peeled off the cocoons to capture the peak stress at the engagement between the output shaft and the gear. In the end, the closed-loop verification of the customized test bench made the theoretical calculations and the hardware-measured data exactly the same. The entire package provides designers with hardcore data support, and always uses airworthiness, not convenience, as the criterion when improving actuator performance.
Xu, Yuanze
Flight Test Analysis Method for Aerodynamic Characteristics of Helicopter Rotor in Level Flight2026-99-18217/17/2026
To analyze flight test failures, ensure flight safety, and provide data support for the aerodynamic design of helicopters, it is necessary to conduct aerodynamic characteristic analysis of helicopter rotors based on flight test data. This article establishes a helicopter rotor aerodynamic model and an aerodynamic parameter identification method in level flight. In this article, we take the flight test data of a helicopter’s level flight performance as an example, and use the genetic algorithm and Particle Swarm Optimization for parameter identification calculation. We obtain aerodynamic parameters such as rotor angle of attack and rotor lift-to-drag ratio in the helicopter’s level flight state, and so on, and analyze the aerodynamic characteristics of the helicopter’s rotor. The results show that the method established in this paper can accurately and effectively obtain the aerodynamic parameters of the helicopter rotor through flight tests. It can also evaluate the aerodynamic characteristics of the helicopter rotor and meet the requirements of the American standard ADS40 for obtaining the aerodynamic characteristics of the helicopter through flight tests. Thus, it has great engineering application value.
Zhao, Jingchao
Dynamic Characteristics Study of the Deployment Process of Aircraft Folding Wing2026-99-18607/17/2026
Folding wing mechanisms are widely applied in aircraft structural design. This design reduces the size of the aircraft, making it easier to store and transport. Whether the foldable wing can successfully deploy determines the completion of the flight mission. Therefore, it is crucial to study the kinematic and dynamic parameters of the mechanism during the deployment process. The deployment of the folding wing typically occurs within milliseconds. The flow field imposes aerodynamic loads on the mechanism, causing it to move, while the large deformation motion of the mechanism, in turn, affects the aerodynamic loads from the flow field. This is a typical fluid-structure interaction (FSI) process. Traditional CFD methods for solving the deployment process in a decoupled manner often result in large errors and cumbersome procedures. To investigate the aerodynamic loads and deformation of the folding wing mechanism during deployment, the ALE algorithm in LS-DYNA was selected to directly solve the kinematic and dynamic parameters of the mechanism in unsteady flow fields, guiding the design of foldable wing mechanisms.
Wei, Ting, Tong, Zongkai, Li, Naitian
Aircraft Evacuation Simulation Study2026-99-18457/17/2026
This study analyzed the evacuation process of aircraft cabin personnel, with a focus on the impact of emergency exit configuration on evacuation efficiency. The research results indicated that the number and location of emergency exits are key factors determining evacuation time. In the case of only one exit, the evacuation time was significantly longer than that of multiple exit configurations. Utilizing three exits could reduce the evacuation time to 76 seconds. Additionally, the age and gender distribution of passengers, as well as priority rules, also had a significant impact on the evacuation process. The study further demonstrated that the activation of emergency exits and rear cabin doors could significantly enhance evacuation efficiency, while the opening of the front cabin door had a relatively smaller effect.
Wang, Kai, Wu, Bin, Li, Guolin, Yue, Chaoyu, Zeng, Tai, Su, Zhengliang
Multi-Frame Centroid Extraction Method for Optical Navigation During the Approach Phase of Small Body2026-99-18517/17/2026
Autonomous optical navigation is one of the important navigation methods for the small bodies approach phase. To improve optical navigation performance during the approach phase to a small body, this paper presents a method for extracting the target centroid from sequential optical images. The process begins with fitting a minimum enclosing ellipse to the detected contours in each frame to obtain an initial estimate of the centroid. Building upon this, edge corner points across adjacent images are matched using normalized cross-correlation, and their displacement is tracked using optical flow techniques. The observed pixel trajectories are analyzed, and a predictive model of pixel motion is formulated based on the geometric relationship between the detector and the small body. By combining the directly extracted centroids with the predicted motion of key pixels, a fusion strategy is developed to improve the reliability of the centroid estimation. Finally, numerical simulation results demonstrate that the method significantly improves the accuracy of centroid extraction, thereby enhancing the overall performance of optical navigation during approach operations.
Liu, Jing, Zhu, Shengying
Key Technologies of Aircraft Flight Test Based on Structural Control2026-99-18257/17/2026
A comprehensive solution integrating advanced sensor technology, structural dynamics models, and intelligent control algorithms is proposed to address the shortcomings of traditional flight testing techniques in monitoring and controlling aircraft structures under complex flight conditions. By establishing precise aircraft structural dynamic equations through fiber optic sensors, an accurate description of the dynamic characteristics of the aircraft structure can be achieved. A distributed structural monitoring system is constructed through FBG to monitor the physical quantities, such as strain and temperature, of key parts of the aircraft in real time during flight testing. Based on the real-time monitoring data, the structural state of the aircraft can be predicted, and the structural response can be actively adjusted by controlling the actuator. The experimental results show that this technology system effectively improves the accuracy of structural monitoring and the effectiveness of control during aircraft flight testing, providing strong guarantees for the safety and reliability of aircraft flight testing, and laying a solid foundation for aircraft structural design optimization and flight performance improvement.
Gao, Sheng
The Impact of Powerplant on Stall Characteristics of Propeller Aircraft2026-99-18377/17/2026
This study focuses on a compact-layout propeller aircraft, investigating how its powerplant influences stall characteristics via combined theoretical analysis of aerodynamic principles and validation with flight test data. Special attention is paid to the effects of propeller slipstream, appropriate evaluation criteria are selected to assess the aircraft’s high-angle-of-attack performance and stall behavior, and the Weissman chart criteria are further adopted to analyze its lateral-directional departure tendencies. A theoretical analysis of the stall characteristics of compact-layout propeller aircraft is conducted. Through flight test data analysis, the stall characteristics of compact-layout propeller aircraft are studied, with an emphasis on understanding how slipstream effects influence their longitudinal and lateral-directional stall characteristics.
Fang, Shengyou, Yang, Xiaoli, Jiang, Tianjun, Fu, Yi
Research on Explicit Topology Construction and Shape Optimization via Hole Deformation2026-99-18367/17/2026
Topology optimization provides innovative solutions for lightweight structural design by rationally arranging material distribution. It enhances structural performance while reducing material consumption and structural weight, thereby significantly lowering production and operational costs and generating enormous economic benefits. In the development of topology optimization, the density-based method has gained widespread adoption due to its easy-to-understand principles. However, this method still faces the following challenges when applied to engineering applications. First, the geometric models generated by topology optimization lack explicit parameter descriptions, leading to data interaction barriers with Computer Aided Design (CAD) systems. Second, due to element discretization and density penalty mechanisms, structural boundaries exhibit rough and blurred characteristics. These problems severely constrain the iterative efficiency of structural design and manufacturing feasibility. To address these issues, this paper proposes a strategy for geometric reconstruction and shape optimization of topology optimization results. The reconstruction process begins with extracting isolines from the density field as a set of contour points. These points are subsequently interpolated with B-spline curves to explicitly represent the geometric boundaries. Shape optimization is then carried out by adjusting the positions of the B-spline control points. Compared to post-processing methods based on graphics techniques for topology optimization, which ignore the volume constraint and performance loss, the structures reconstructed in this paper exhibits the following advantages: structural boundaries are smoothed and characterized with explicit parameters, reducing performance loss caused by geometric reconstruction while satisfying volume constraints. This paper successfully establishes compatibility between topology optimization and CAD systems, facilitating the transition from conceptual design to manufacturing.
Tang, Yuting, Li, Yu, Luo, Jiaxiang, Chen, Junwei, Zhou, Weien, Yao, Wen
Machine Learning-Based Prediction of Landing Dynamic Response for Bogie Landing Gear2026-99-18297/17/2026
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Zhang, Hong, Fang, Wei, Zhao, Junfeng
Analysis of Structural Stiffness Indicators of Manned Lunar Vehicles2026-99-18277/17/2026
The structural stiffness of a manned lunar vehicle is a core indicator ensuring its stable operation in the complex lunar environment. The vehicle’s body structure must meet multiple requirements, including high stiffness, lightweight design, and adaptability to lunar surface conditions. Since lunar gravity is only 1/6 of Earth’s and the terrain is rugged and dusty, the body structure must employ a high-stiffness design to withstand driving impacts and resist deformation, thereby preventing mechanical failures or safety hazards for crew members caused by excessive structural distortion. However, excessive structural stiffness would result in an overweight vehicle body, conflicting with the spacecraft’s lightweight requirements. Thus, the structural stiffness index should be optimized to a lower value while ensuring safe operation during lunar surface driving without compromising performance. This paper calculates and determines the structural bending and torsional stiffness indicators for the manned lunar vehicle’s body through simplified model calculation and the FEA method.
Shen, Zhenghui, Wu, Yingjia, Yang, Jianfeng, Wang, Weijun, Zhang, Chongfeng, Han, Liangliang
Analysis of the Nonlinear Behavior of the Composite Helicopter Horizontal Centralwing Skin2026-99-18327/17/2026
Test results of the composite helicopter horizontal central-wing under symmetric and unsymmetric loads showed that the strain value of the lower skin would turn from negative to positive, showing a nonlinear behavior. FEM results of the linear and nonlinear analytical approach showed a great difference. The strain value of the lower skin remains negative and decreases linearly when using a linear FEM analysis. The strain value of the lower skin would turn from negative to positive when a nonlinear FEM analysis is applied, and this result agrees well with the test results. Besides, the results of the FEM buckling analysis showed that the buckling load of the lower skin is considerably higher than the value at which the skin would show a nonlinear behavior. Therefore, the specific behavior is a result of the nonlinear property of the structure, not buckling.
Wang, Zhe, Zhang, Tiesong, Li, Mengjia, Chen, Puhui, Huang, Zhiwen, Wang, Binwen
Flight Test Methodology for Verification of Precipitation Static Protection in Civil Aircraft Radio Navigation Systems2026-99-18097/17/2026
The verification of Precipitation static (P-static) protection for the radio navigation system of civil aircraft is a critical test item for airworthiness certification. However, determining the presence of P-Static on the aircraft fuselage and assessing whether its discharge interferes with the radio navigation system remains challenging, with testing methods still under exploration. By analyzing airworthiness certification test provisions, the necessity of conducting flight tests for P-static protection verification of the radio navigation system was clarified. Based on existing conditions for civil aircraft flight tests, a comprehensive flight test method was proposed to verify the P-satic protection capability of the radio navigation system. This method includes determining external meteorological conditions, measuring electrostatic parameters, and designing aircraft maneuvers and states. The test plan was validated on a test aircraft. Discharge current data measured on a discharger indicates that during the flight of a civil aircraft through cirrus clouds, negative charge accumulated on the aircraft's surface, leading to electrostatic discharge. The maximum peak discharge current recorded was 330 μA. P-satic radiation field data were obtained near the Automatic Direction Finder (ADF) antenna; the radiation energy is primarily concentrated within the 200 MHz range, with some energy distribution still observed between 200 MHz and 500 MHz. Within the 200 MHz range, the signal amplitude exceeds the background noise, and stable peaks appear at multiple frequency points, with the maximum amplitude reaching up to 50 dBm.confirming the presence of a P-Static environment. This achieved the objective of evaluating the functional performance of the radio navigation system in an electrostatic environment, providing technical support for P-Static protection verification flight tests and offering a reference for the practical application of electrostatic protection design.
Han, Chunyong, Wang, Fusheng
Landing Site Selection and Visual Scene Generation Based on LiDAR Point Cloud2026-99-18197/17/2026
This paper focuses on autonomous drone landing scenarios. Addressing the core requirements of accurate landing site assessment and intuitive visual presentation, it conducts in-depth research on the application of 3D LiDAR (TOF technology) point cloud data. LiDAR captures point cloud data containing 3D coordinates and reflection intensity values. While sparse, non-uniform, and disordered, its high measurement accuracy and strong anti-interference capabilities make it a key sensor for landing terrain perception. Based on a review of recent research results from related teams, this study designed and implemented a comprehensive technical solution: First, raw point cloud data is acquired via the UDP protocol combined with an SDK interface. Preprocessing is then performed using voxel grid filtering (downsampling) and radius filtering (denoising). The assessment area is then divided into a row-by-column grid. A sliding window method is used to calculate the elevation difference, empty grid ratio, flatness, and slope of each grid. Based on these attributes, the grids are classified into six categories: Risk, Warning, Blank, Unknown, No Landing, and Landing. Finally, a grid attribute coloring method and OpenGL 3D rendering are used to generate the visual scene. Through the development of verification programs and moving obstacle experiments, it has been proven that the solution can efficiently process point cloud data and accurately identify safe landing areas, providing key technical support for the engineering realization of the autonomous landing function of drones, and also laying the foundation for the intelligent development of drone landing decisions in complex environments.
Guo, Hangyu, Shi, Zhe
Attitude Control of a Variant Flying Wing UAV Based on L1 Adaptive and Fuzzy Clustering2026-99-18587/17/2026
This study presents a full-envelope attitude-stabilisation and trajectory-tracking strategy for morphing flying-wing UAVs operating in highly nonlinear and strongly coupled conditions. The approach integrates fuzzy C-means (FCM) envelope partitioning with L1 adaptive control. Small-disturbance linear models are first generated at multiple altitude–Mach trim points; the FCM algorithm then performs unsupervised clustering in the state space, yielding representative subintervals that capture local flight-dynamic characteristics. The optimal cluster number and fuzziness exponent are selected using the partition coefficient, partition index, partition entropy, and Xie–Beni indices. For each sub-interval, an LQR baseline controller is designed and augmented by an L1 adaptive compensator, where a low-pass filter decouples adaptation from robustness to guarantee specified transient-performance bounds under matched/unmatched uncertainties, actuator saturation, and external disturbances. A feed-forward pre-filter realises online decoupling of the multi-input multi-output channels, thereby enhancing adaptability to variable sweep angles and large aerodynamic variations. Simulations covering low-speed/small-sweep and high-speed/large-sweep scenarios demonstrate that the proposed method sustains robust stability across the clustered envelope, outperforming conventional control schemes and confirming its engineering applicability.
Tang, Longhao, Sun, Xiaoxu, Liu, Changlin
Study on the Effect of Flap Parameters on Hydrodynamic Characteristics of Marine Flap Rudder2026-99-05267/10/2026
By tweaking the flap’s deflection angle, the flap rudder significantly enhances the hydrodynamic performance. This study investigates the influence of the location of the flap rotation axis and the size of the flap’s deflection affect how well the rudder performs in the water, using computer simulations to obtain high-resolution flow-field data. The results demonstrate that the flap rudder consistently generates more lift than your standard rudder. Prior to stall, pushing the flap rotation axis further back results in less lift, but also less drag. For maximum lift at small or moderate angles of attack, a rotation axis located at 0.75 c provides the highest lift coefficient, whereas the 0.85 c configuration combined with δ = 25° offers the best compromise between postponed stall and maintained lift-to-drag ratio. Put the pivot at 85% chord and set the flap deflection to 25 degrees, and an optimal configuration is achieved in terms of lift and drag. The configuration yields a stall angle pushed out to 16 degrees and a maximum lift coefficient that jumps to 3.86. That’s a significant increase of 15.77 % over what you’d get with 15° flap deflection. Ultimately, this research lays the groundwork for designing better flap rudders and gives us some serious pointers on how to increase the performance of ship rudders in the real world.
Liu, Zirong, Wang, Jianming
Helicopter Engine-Rotor System CompatibilityARP704A (Current)7/2/2026
This SAE Aerospace Recommended Practice (ARP) recommends a methodology to be used for the design, analysis and test evaluation of modern helicopter gas turbine propulsion system stability and transient response characteristics. This methodology utilizes the computational power of modern digital computers to more thoroughly analyze, simulate and bench-test the helicopter engine/rotor system speed control loop over the flight envelope. This up-front work results in significantly less effort expended during flight test and delivers a more effective system into service. The methodology presented herein is recommended for modern digital electronic propulsion control systems and also for traditional analog and hydromechanical systems.
S-12 Powered Lift Propulsion Committee
Integrated DC Boost Charger in Post-800V Architecture with Open-End Winding Machine – Magnetic-Domain Modelling and Torque Analysis2026-01-07397/1/2026
Next-generation powertrain architectures proposed within EU Horizon projects adopt operating voltages above 800 V, providing improvements in efficiency as well as reductions in copper usage and system weight. However, post-800 V vehicles must remain backward compatible with existing 400 V and 800 V charging infrastructure, which requires the installation of an additional onboard DC boost charging unit on the vehicle. This paper proposes an integrated DC boost charging solution that reutilizes the open-end winding electric machine and the traction inverter of the electric powertrain, enabling backward compatibility while further reducing system cost and weight. In charging mode, the electric machine is repurposed as a passive inductive component, imposing a strict requirement of stationary operation with zero torque generation, which fundamentally differs from the driving mode characterized by rotor rotation and electromagnetic torque production. Consequently, conventional electric machine modeling approaches based on the rotor-oriented reference frame are not applicable to charging operation due to the unsymmetrical and unbalanced three-phase currents in the machine windings. To evaluate the machine behavior and develop charging control strategy, this paper introduces a magnetic-domain model based on physical model using phase self- and mutual-inductance parameters, from which the electromagnetic torque is directly derived based on the interaction between magnetic flux and phase currents. The simulations compare the charging current ripple and electromagnetic torque generation of a stationary open-end winding machine under two charging configurations: open-winding charging and neutral-point charging. The results show that the open-winding charging configuration exhibits lower current ripple than the neutral-point charging configuration due to higher inductance utilization. However, a non-zero charging torque is generated in the open-winding charging configuration and is strongly dependent on rotor position. The specific rotor positions corresponding to zero torque are identified and used to optimize the charging process.
Wang, Haoran, Kallur-Krishnamoorthy, Rajesh, Neuhaus, Christoph, Andert, Jakob
Who’s Riding? Machine Learning-Powered Rider Identification from E-Bike CAN Data2026-01-07787/1/2026
This study investigates the feasibility of identifying individual e-bike riders based on CAN data using machine learning techniques. Datasets from 12 test riders performing various predefined cycling tasks on a dynamometer test bench are collected and used to ensure controlled and reproducible conditions. The recorded CAN data includes various sensor signals, such as power output, cadence, torque, and the used support mode. After pre-processing, two different methods of feature extraction are tested and compared, one based on snapshots of the data and one based on driving events such as braking and accelerating, measured by calculating statistics of the riding data over sliding windows. A range of machine learning models is employed to classify riders based on their distinct riding patterns using the extracted features. The evaluated models comprise KNN, Random Forest and Naïve Bayes. The findings demonstrate the efficacy of machine learning in differentiating riders, with Random Forest and KNN achieving the highest and most robust accuracy among the tested models. The KNN-model achieves up to 99% accuracy, the Random Forest up to 75%. The paper analyzes the influence of different signals, feature extraction methods and model parameterizations on the results. The results show that machine learning-based rider identification using CAN data is a viable approach for enhancing e-bike security, authentication, and personalization. Potential applications include theft prevention, automatic user recognition for personalized assistance settings, and access control. Future research could include the exploration of the impact of additional sensor data, real-world outdoor conditions, and deep learning approaches, with the aim to further enhance identification accuracy and efficiency.
Simmann, Gabriel, Rauch, Yannick, Beißert, Florian, Kriesten, Reiner
Evaluation of Helicopter Turbine Engine Linear Vibration EnvironmentAIR1289A (Current)6/29/2026
This SAE Aerospace Information Report (AIR) outlines a recommended procedure for evaluation of the vibration environment to which the gas turbine engine powerplant is subjected in the helicopter installation. This analysis of engine vibration is normally demonstrated on a one-time basis upon initial certification, or after a major modification, of an engine/helicopter configuration. This AIR deals with linear vibration as measured on the basic case structure of the engine and not, for example, torsional vibration in drive shafting or vibration of a component within the engine such as a compressor or turbine airfoil. In summary, this AIR discusses the engine manufacturer’s "Installation Test Code" aspects of engine vibration and proposes an appropriate measurement method.
S-12 Powered Lift Propulsion Committee
Automosphere: Exploring Vehicle Heads-Up Display with Weather-Related Windshield Cues for Passive Fatigue Management12-09-03-00256/26/2026
Passive fatigue can cause accidents with automated and regular vehicles. A proof-of-concept prototype [made with light-emitting diode (LED) matrices and white LED (WLED)] and a preliminary comparative usability test (N = 7) are used to study whether the active manipulation of simulated weather cues can be a potential countermeasure to passive fatigue. Participants rated system suitability, system impression, and their fatigue level similarly when they viewed a weather windshield heads-up display (HUD) versus a speedometer windshield HUD [no significant differences found and relatively small 95% confidence interval (CI) ranges around 0]. Qualitative analysis of interviews found that participants saw the potential value of the weather display and that display placement, dynamic graphics, and user activation were commonly mentioned themes. These results suggest the concept is theoretically possible, though further work is needed to prove the concept in practice.
Ensafjoo, Mohsen, Li, Jamy
Numerical Investigation of Inverted Airfoils in Ground Effect for Motorsport Applications01-19-01-00046/25/2026
Ground effect plays a critical role in enhancing the aerodynamic performance of race cars by increasing downforce without a proportional rise in drag. Despite its importance, the influence of airfoil geometry on inverted airfoils operating in ground proximity remains underexplored in open literature. This study addresses this gap through a detailed numerical investigation of chord-dominated ground effect using two-dimensional Reynolds-Averaged Navier–Stokes (RANS) simulations. A range of NACA four-digit airfoils is systematically analyzed to isolate the effects of camber, thickness, and camber location on aerodynamic performance in ground proximity. Results show that increased camber enhances downforce and efficiency both in and out of ground effect; thinner airfoils yield higher downforce and efficiency in ground effect; and forward camber locations outperform rearward ones in maximizing downforce contrary to out-of-ground-effect trends. Detailed pressure distribution and flow separation analyses explain the underlying mechanisms, offering actionable guidelines for optimizing ground effect airfoil design in motorsport.
Chowdhury, Rohan, Shukla, Dhwanil
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