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ACBG Rolling Element Bearing Committee
In order to ensure that the high-caliber artillery ammunition fuses can successfully complete their combat tasks with high quality, it is necessary to optimize the design of their structure and conduct simulation verification of their performance. Through optimization design, this paper determined that the distance between the antenna plate and the wind cap of the proximity detonation module of the high-caliber artillery ammunition fuse is 6.2mm, and the thickness of the wind cap top is 12.9mm; it also determined that in the coaxial line feeding mode, a circular patch is used as the antenna shape, with the lowest return loss (reaching -38.5244 dB), which is conducive to the emission of electromagnetic wave energy; by introducing the methods and processes of intensity simulation analysis and aerodynamic thermal simulation analysis, as well as the methods of performance verification, this paper provides reference and guidance for the simulation analysis of similar systems.
Liu, LiwenSun, ZhangyiNing, QuanliCai, Canwei
The extreme cold environment has a significant impact on the mechanical properties of welded hollow ball nodes, which are crucial components in large-span steel structures. In this paper, based on the comprehensive test data of drum-shaped welded hollow sphere nodes from Beijing Daxing International Airport, a sophisticated finite element model incorporating welding residual stress is established. Through detailed static loading analysis and systematic hysteresis performance studies, the research thoroughly explores the influence mechanisms of low temperature on node bearing capacity, deformation capability, and energy dissipation performance. The investigation reveals that while the bearing capacity of the nodes increases significantly in low-temperature environments, both their plastic deformation capacity and energy consumption performance are notably reduced. These findings provide valuable theoretical references for the design and optimization of large-span mesh frame structures
Luo, YanzhiJin, Changming
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
Zhang, XuSong, GuangmingWang, BaozhongZhao, JinpengChen, Qianshuo
In this study, five resin-based brake pad samples with modified fly ash contents of 0%, 4%, 8%, 12%, and 16% were prepared to investigate the influence of fly ash content on the comprehensive performance of the friction materials. The tribological properties of all samples were evaluated under temperature conditions ranging from 100 °C to 350 °C, and their overall performance was assessed using five evaluation indices. Based on the AHP-MOORA algorithm, sample F12 exhibited the highest comprehensive weighted score of 0.11, followed by samples F0 and F8 with scores of 0.10 and 0.09, respectively, indicating a slight decline. In contrast, the comprehensive weighted scores of F4 and F16 were relatively low, at 0.05 and −0.01, respectively. Among the five composites, F12 demonstrated the best overall performance, with F0 and F8 ranking next, while F4 and F16 performed poorly. These results suggest that, within a certain range, increasing the fly ash content can enhance the comprehensive
Li, XiaobiaoHe, KangZhao, ZhuanzheWu, BoSun, Fei
Ball screws, as classic high-precision transmission structures, are widely used in various linear motion mechanisms. To meet the needs of space applications, it is necessary to address issues such as microgravity and long lifespan to enhance the in-orbit lifespan and reliability of ball screws. Traditional oil or grease lubrication methods are often unsuitable for space environments due to microgravity and vacuum evaporation problems. This paper conducts relevant research on lubrication design, friction pair design, and friction and wear verification to solve the lubrication and lifespan issues of long-lifespan ball screws for space applications.
Xie, WenZhao, JianGong, KangHu, XiaonanGuo, MengleiJiao, Hanyu
In this study, a polylactic acid (PLA)/tea polyphenols (TP) polymer blend was developed for coronary artery stents. Using a high-efficiency mixer, we prepared optimal mixtures, which were then hot- and cold-pressed into thin films of varying thicknesses. Scanning electron microscopy (SEM) and contact angle tests were used to analyze surface changes and biodegradability over time. The mechanical properties of drug-loaded films were evaluated via a universal testing machine. Tea polyphenols enhanced specimen hydrophilicity, biocompatibility, and stability by reinforcing the microstructure. This is crucial for long-term implants as it extends service life and minimizes complications from material fatigue.
Sun, Xuyu
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, MenglongXu, ZhaoyangWang, YongqiangMeng, LiTan, JiaxinXuan, JintingBie, DaweiShao, Lintao
Tubing Ultimate burst strength Full scale test
Cheng, WenjiaYang, HongbinGe, YuanZhong, ChongdiMeng, LingkunJi, BingyinShi, Jiaoqi
In response to the current airworthiness regulations’ inability to cover the stall flight test requirements under icing conditions of civil aircraft with high-angle-of-attack restriction function and the lack of relevant flight test technologies in China, a study was conducted on the differences in airworthiness provisions for stall characteristics under icing conditions of such aircraft. Key technologies, including simulated ice accretion stall flight test methods, ice installation strategies, and data analysis techniques, are proposed and successfully applied to a specific civil aircraft. The results demonstrate that the methodologies proposed in this paper can effectively support simulated ice accretion stall tests, providing valuable insights for other similar aircraft.
Zhang, Haini
Accurate prediction of ground settlement induced by rectangular pipe jacking, a prevalent trenchless technology in urban infrastructure development, remains a significant challenge. This study addresses this by developing and evaluating a robust machine learning (ML) framework. Leveraging 104 sets of field monitoring data from the Liuye Avenue West Extension rectangular pipe jacking project in Hunan, China, key construction parameters including jacking force, advance rate, and grouting pressure were utilized as inputs to predict ground settlement. A Particle Swarm Optimization (PSO) algorithm was integrated for automated hyperparameter tuning of six distinct ML models: standalone Least Squares Support Vector Machine (LSSVM), Backpropagation Neural Network (BPNN), Random Forest (RF), and their respective PSO-optimized counterparts. Comprehensive performance evaluation using Mean Squared Error (MSE), Mean Absolute Error (MAE), and Coefficient of Determination (R^2) revealed that the PSO
Hu, ShiweiHu, RongZhang, HongChen, YiHu, Da
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
Gu, ChengzhongXu, HanweiLuo, RirongRen, Fushan
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
Gu, KexuanZhu, YiXie, LiangWang, Wei
The Mellin non-uniformly distributed moving blade method was adopted to conduct CFD numerical analysis and sample experimental tests on the axial-flow turbines before and after optimization using the uniformly distributed and non-uniformly distributed design methods, respectively. In the original design, five blades were evenly distributed in the 360° circumferential direction, and the non-uniformly distributed angles were 46°, 102°, 46°, 83°, and 83°. CFD numerical analysis shows that due to the low rotational speed of the turbine and the absence of a sealing structure at the blade tip, factors such as tip noise leakage and backflow have little impact, and the flow field pulsation is mainly caused by the blades themselves. The non-uniformly distributed design can significantly enhance the work-doing capacity of the blades. At 90% of the blade height, the torque can be increased by up to 60%, but at the same time, the axial force on the blades also increases accordingly. Near 80% - 90
Wu, AipingMa, TianliWang, ShimingDing, Chengling
Generally, the allowable strain design is adopted for composite structures, which should ensure that the structure has sufficient strength and stiffness under the service load, and the safety margin should be greater than zero under the design load. The thesis develops a structured design for a stabilizer of civil aircraft based on standards and airworthiness requirements. The main task of this thesis is to compare the results of the all-mental structure and composite material structure of stabilizer on weight reduction at sufficient strength and stiffness.
Pi, RungeLv, BaoliangZhang, Liang
The mechanical behavior of a certain solid propellant is not only obviously related to time, temperature, and load loading history, but also is a viscoelastic plastic material under certain conditions. Based on the principle of creep deformation superposition, the strain of the solid propellant material is decomposed into a viscoelastic part and a viscoplastic part, and the nonlinearity of the viscoelastic-plastic constitutive model is manifested by the introduction of nonlinear coefficients. According to the characteristics of the viscoelastic-plastic model of the solid propellant material, the relevant tests were designed. The viscoplastic parameters were determined by using the creep recovery test data of multiple cycles until the failure of the propellant material sample. The viscoelastic parameters of the solid propellant material were obtained by using the data from recovery tests performed under different stress conditions.
Zhang, JianbinSui, JiulingYao, BaotaiCheng, DongLi, Yiming
Advanced composite materials have garnered widespread attention in the aerospace and other fields with stringent weight requirements, owing to their superior properties, such as lightweight, high strength, high modulus, and corrosion resistance. Compared with traditional metal materials, advanced composite materials can reduce structural weight by 30%. Lattice structures possess unique characteristics, including high designability, low cost, and high damage tolerance. As a specialized reinforced structure, they have been identified as one of the key structural configurations for next-generation aircraft. Composite lattice structures, which integrate the advantages of composite materials and lattice architectures, provide an ideal structural material for achieving lightweight and multifunctional aerospace equipment. However, due to the intricate geometries and diverse functional design requirements of lattice structures, the fabrication of these structures presents significant
Han, ShuhaoLv, ZhenMa, ChengXiu, ZhifengSong, Yanhua
To address the detection and monitoring needs of fatigue damage in ferromagnetic materials, this paper proposes a nondestructive testing method based on the evolution of magnetic hysteresis characteristics. By constructing a hysteresis loop measurement system, the variation patterns of coercivity (Hc) in Q235 steel specimens under cyclic loading were investigated, revealing three-phase characteristics of fatigue damage: the initial linear growth phase (N ≤ 8,000), the rapid rise phase (8,000 < N ≤ 12,000), and the stable oscillation phase (N > 12,000). Experimental results demonstrate that the relationship between coercivity and damage degree (D) can effectively characterize the processes of crack initiation, propagation, and instability, with significant inflection points observed at D = 0.6 and D = 0.8. The quantitative model based on coercivity provides a novel method for early warning and condition assessment of fatigue damage, offering advantages such as non-contact operation and
Chen, LiDing, Keqin
To obtain additional space for industrial sorting and assembly line labeling operations, this study conducts an analysis of the four-bar mechanism. Based on this analysis and combination, the redundant parallel mechanism is introduced. That is, on the basis of the traditional parallel mechanism with central rotation, the objective of expanding the working space is achieved. The degree of freedom of the screw theory and the disparities between the working space of this mechanism and that of the traditional mechanism are analyzed. Finally, through application analysis, it is demonstrated that the working space of this mechanism is variable and that the mechanism can adapt to diverse workplaces.
Li, WenqianZhang, Xiaojie
For large-bore marine methanol / diesel dual-fuel engines, this study investigates the formation characteristics of unregulated emissions through experimental methods and explores the mechanisms by which engine load and injection timing influence the emissions of unburned methanol and formaldehyde. The study was carried out on a supercharged intercooled inline six-cylinder engine, and Fourier Transform Infrared Spectroscopy (FTIR) was used to monitor the exhaust composition in real time. The study shows that methanol released in the exhaust is due to the incomplete combustion of the methanol fuel. In the combustion process of methanol fuel, formaldehyde mainly arises from two pathways, the first of which is the partial oxidation of methanol inside the cylinder; secondly, the unburned methanol in the exhaust gas oxidizes in the exhaust pipe to generate formaldehyde. As the load increased from 25% to 100%, the unburned methanol emissions decreased by 29%, and formaldehyde emissions
Jiang, YuqiLi, HongmeiZhang, WenzhengLi, XiaoZheng, LiangMeng, YangqianGu, XiananHua, Hanqing
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
Jing, MinJia, ZhilongZhang, HualeiLiu, MinjieGan, XinhuaGao, Jinyu
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, JiajunMing, ChaoAn, ZhichaoNiu, ZhaoqiWen, Guangbao
This study aims to solve the trajectory optimization problem of multi degree of freedom micro air vehicle (MAV) with the aim of improving its flight performance through technological innovation. A multi degree of freedom trajectory optimization (MDFTO) method with sideslip angle and angle of attack as the core control variables was proposed for multiple complex constraints in combat environment, such as terminal accuracy and overload limitation. This method can more accurately characterize and adapt the strong nonlinear, dynamic coupling and time varying characteristics of the MAV in high-speed maneuvering flight. In order to solve this MDFTO problem with multiple constraints and strong nonlinear characteristics efficiently, the hp adaptive pseudospectral method is used in this study, and is verified by simulations based on the GPOPS-II optimization platform. The algorithm has the advantages of highly accurate discrete state and control variables, efficient processing of path and
An, ZhichaoMing, ChaoWen, Guangbao
Due to the constraints of manufacturing costs and cycles, it is difficult to simulate the full-scale operating conditions of aircraft electrical power systems. Usually, scaled-down low-power systems are used for prototype development and experimental research. This paper puts forward a systematic framework for developing scaled physical models of aircraft electrical power systems by using similarity theory. In this paper, according to the general design principles of DC-DC converters, a 10-kW low-power DC-DC converter and a 250-kW high-power DC-DC converter are designed. Mathematical models for both systems are developed, and a time-domain performance index analysis is carried out using the per-unit dynamic equivalence principle. A metric conversion model is established and equivalently mapped to a high-power DC-DC converter simulation model. The waveform consistency between the converted model and the aforementioned 250-kW high-power model is verified, which shows the validity of the
Ma, HuanAi, FengmingBi, WenyanPei, XiaoningLiu, Liangliang