The opening mechanism is the key part of the civil aircraft cargo door to open and close, and it is also one of the difficulties in the design of cargo door. In this paper, according to the basic stress situation of the four-link of the opening mechanism, the four-link of the opening mechanism and its connecting mechanism are processed with ABAQUS finite element analysis software, and the processed four-link and its connecting mechanism are imported into ADAMS software, and the rigid-flexible coupling model of the mechanism is established. Then, PID controller is set up in ADAMS software to simulate the real motion process of opening and closing the cargo door. Meanwhile, dynamic simulation is carried out to obtain the force situation under different working conditions in the process of opening and closing. The simulation results show that the stiffness and strength of the four-link and the connecting structure of the designed cargo door opening mechanism meets the requirements of use, and can provide theoretical support for the design simulation and optimization of the non-back mechanism in the next opening mechanism.

The high temperature generated on the contact interfaces of the conical friction element in clutches due to the sliding frictional heat should be responsible for the synchronization failure. In this study, an analytic model taking account of the capsizing moment and stress singularity at the end of the contact interface is established to solve the contact pressure distribution. Then, a three-dimensional finite element model has been developed to analyze the transient thermal behavior of the conical friction element. The contact pressure and temperature distribution generated along the contact interfaces are investigated and compared between the proposed new model, the combined wear assumption, and the uniform pressure assumption. Furthermore, the variations in temperature obtained from the new model and the other two assumptions are compared to the experimental results. The results show that the temperature simulated by the new model has a good agreement with reality. The maximum temperatures obtained by the new model are 95.53 °C and 71.67 °C, and the measured values are respectively 84.98 °C and 65.46 °C at the measuring position under the given two working conditions.

The non-return mechanism is the key device that plays the role of braking in the opening-and-closing electric actuator of an amphibious aircraft hatch door. The ball-and-socket contact pair, providing the pressing force, and the multi-disc friction pair, supplying the braking torque, are two core components in the non-return mechanism. In this paper, the dynamic model of the non-return mechanism is established considering the freedom of rotation-translation. Based on MATLAB/Simulink, the solution framework of the overall dynamic model is built. The dynamic response characteristics of the non-return mechanism in the process of reverse load braking, forward load braking, and continuous closing are analyzed. The braking time and the angular displacement of the output shaft in the braking phase have been presented. Compared with forward load braking, reverse load braking has a longer braking time and smaller angular displacement of the output shaft. In addition, the compaction function of the ball-and-socket contact pair is verified by experiment, and the influence of the cone angle, distribution radius of the ball socket, and the steel ball diameter on the pressing force has been discussed. This study provides a theoretical basis and parametric design platform for the design and optimization of non-return mechanisms, which can shorten the product development time.

Contact characteristics of friction pair play a crucial role in the torque transmission capacity and temperature rise prediction of automotive clutches. In this study, a Multi-cone friction pair used in wet clutches has been proposed. Each pair of conical contact is considered as the contact between a finite stiffness punch and an elastic half-plane, and 2D finite element (FE) models are developed to calculate the contact load assignments. Considering the capsizing moment and stress singularity at the end of the contact interface, an analytic model is established to obtain the contact pressure distribution on each conical contact interface based on the results of contact load assignments. Finally, the numerical examples are given, and the influences of axial load, mating material characteristics, friction coefficient, and cone angle on contact pressure distribution have been discussed in detail, which supplies the guidance of parameters design for Multi-cone friction pair.

针对一种多片式摩擦副结构,基于Python 语言对ABAQUS软件的前处理过程进行二次开发,简化多片式摩擦副制动仿真建模过程.通过编写主控程序Frictionmodel.py,图形界面程序FrictionmodelDB.py和关联程序Frictionmodel_plugin.py,实现系统建模程序定制,对不同对数、不同尺寸的多片式摩擦结构进行快速建模,基于三维瞬态热传导理论进行航空用舱门无返回装置紧急制动工况下瞬态热应力场的有限元分析计算.结果表明,随着摩擦副数的增多,制动力增大,制动时间逐渐减少,制动温升也会降低;但接触压力分布情况也会逐渐变差,出现应力集中.通过对比分析,三对副摩擦片结构可以保持高效制动的同时,满足结构尺寸及温度要求.

The quality interaction relationship in the automatic assembly process of a missile was discussed.The data were divided into types, the continuous variables in the assembly process were analyzed by Pearson correlation, and the grey correlation analysis method was used for comparison and verification.The contingency analysis of discrete variables was carried out, and the correlation was visually displayed by using the corresponding analysis diagram.Then, through the correlation analysis results of the assembly process data, the upstream process indicators B 1 and m 1 should be improved, so as to greatly improve the quality of the downstream process B 2 .For the key process h,a more significant assembly quality improvement effect could be obtained through the strict control of the parts batch and the guidance and training to the assembly workers.Finally, the correlation analysis software was designed to lay the foundation for the improvement of acquisition means, comparison and verification before and after, and data fusion analysis.

盘式制动器在制动过程中涉及到接触应力场、摩擦温度场以及盘体转动角速度和能量等的急剧变化.对列车制动器进行曲面构型设计,并改进制动器结构使它适用于碳陶摩擦材料.基于直接热力耦合的有限元方法,对比平面和曲面两种制动器结构的仿真结果,得到二者在相同工况下的温度场分布、接触应力分布以及角速度和能量的时间历程曲线.结果表明:曲面盘式制动器的制动效率明显高于平面制动器,但其温度场和接触应力分布状态不是十分理想.

Wear failure is greatly affected by the structure, including the structure of the whole machine and the shape and size of parts. The multi-cone wet clutch can effectively improve the torque transmission capacity, but the contact form of friction pair is more complicated, which makes the wear and structure strongly coupled. This paper has discussed the influence of operating conditions and structure parameters on the sliding wear of multi-cone friction pair with finite element method (FEM). Based on Archard’s wear law, the sliding wear simulation procedure is carried out to calculate the wear displacement, and the orthogonal design is also applied in order to select a few simulation schemes with strong representativeness. Analysis of variance (ANOVA) is performed to quantify the influence of various factors on the wear of multi-cone wet clutch. This paper can guide the design of multi-cone friction wet clutch.

Tooth root bending stress and surface contact stress are two major determinants of the load carrying capacity of gear drives. Generally, a high contact ratio has the potential to enhance the gear strength. In this paper, the basic procedures and methods for constructing a high-contact-ratio (HCR) internal spur gear pair with the arc path of the contact are presented. The effects of design and modification parameters such as deflection angle, modification angle, and addendum coefficient on gear drive are analyzed in detail based on 2D finite-element models (FEMs). A comparison of experimental and finite-element analyses (FEA) of the bending stress, contact stress, and contact ratio between HCR and involute internal spur gear drives was conducted to demonstrate the advantages of the HCR gear drive in terms of load capacity. The results show that appropriately increasing the deflection angle and addendum coefficient is beneficial for reducing bending and contact stresses. It was also observed that the bending and contact stresses of a HCR pinion are lower than those of an involute one. Moreover, the contact ratio increases with input torque.

基于润滑力学和微凸体摩擦原理,建立了多锥构型摩擦副同步过程的数学模型并进行数值求解,分析了多锥构型摩擦副同步过程中主从动片初始相对转速、油膜厚度、油膜承载力、微凸峰承载力、黏性剪切转矩、粗糙摩擦转矩等随同步时间的变化规律.利用所建模型研究了锥角、摩擦锥面数量、表面粗糙度、初始相对转速和加载压力等因素对同步过程的影响规律.结果表明:多锥构型摩擦副具有明显的楔形自增力效应,较小的轴向加载力可提供很大的锥面接触力;减小锥角、增加摩擦锥面数量、增大表面粗糙度和轴向加载压力均可提高同步转矩,缩短同步时间;同步时间与初始相对转速大致呈线性关系.

The temperature plays a vital role in the tribology properties and failures of scuffing and excessive wear during the engagement of wet clutch. The contact pressure distribution and friction heat flux have been calculated based on the combined wear law of the conical joint, and a three-dimensional transient thermal analysis finite element (FE) model with the detailed structure for the multi-conical friction plate is established. The influence of different operating conditions on the highest transient temperature of friction plate is analyzed, and the temperature of the specified location and the radial distribution are given. The results show that the highest temperature appears near the middle of the engagement period and locates at the edge line of the cone top. The temperature of inner conical surface is higher than that of the outer conical surface.

The mesh stiffness and contact ratio of gear drive are very important factors which have a great impact on the dynamic load. Contact ratio also affects the fluctuation and the mode of change of the mesh stiffness. In this research, a novel high contact ratio internal gear with a circular arc contact path is introduced. However, the irregular tooth profile of non-involute gear usually causes the numerical calculation to be more complex. To get the torsional mesh stiffness of a pair of internal spur gear, the two-dimensional finite element models of involute internal gear and high contact ratio internal gear are presented and compared. In addition, the influence of input torque on torsional mesh stiffness and contact ratio are analyzed. The mesh stiffness of a single tooth pair and the effect of different engagement positions on mesh stiffness are obtained and compared. Finally, experimental measurement of contact ratio is established by strain gauge technique. It is shown that the torsional mesh stiffness increases with the increase of input torque, and the greater the contact ratio, the smoother the gear drive.

针对一种模块化液压动力换挡变速器样机,设计了动力性换挡规律.对于稳态规律不能适应车辆动态工况以及油门突变情况下易导致误换挡问题,以油门开度、油门变化率、加速度和车速为参数,设计了4参数的模糊控制方法进行修正.分析车辆在坡道工况下出现循环换挡的原因,基于递推最小二乘法设计坡道预测和坡道换挡控制方法.仿真实验表明,模糊控制方法可以有效提高整车起步动力性,消除快速给油导致的误换挡;所设计坡道换挡控制方法可以有效识别坡度并消除循环换挡.

为实现一种新式模块化变速器试验样机的自动换挡功能,设计了样机配套换挡液压系统,并对换挡过程进行仿真建模.基于刚体动力学原理对二挡模块样机进行分析,并利用MATLAB/Simulink建立包括传动系和液压缸的整体仿真模型,利用溢流调压控制,设计一套简化换挡液压系统.以输出轴扭矩变化率和输入轴最低转速作为评价指标,研究充油流量、复位弹簧预紧量等参数对该新型结构样机换挡品质的影响规律.用换挡试验验证了模型和样机换挡可信度.结果表明,充油流量决定零件运动速度和液压缸内压力上升速度,影响换挡速度和换挡制动时间,增大流量可有效消除换挡制动,但会引起冲击增加;使用较小的弹簧预紧量可以减小换挡冲击.