The work aims to improve the mechanical properties of AZ91 magnesium alloy at more than 120 ℃. Ca, Si and La/Ce mixed rare earth elements were added to AZ91 alloy. Isothermal extrusion was carried out at 360 ℃ with an average extrusion speed of 1.2 mm/s and an extrusion ratio of 30︰1 to explore the effects of Ca, Si and La/Ce mixed rare earth elements on the mechanical properties, phase composition and microstructure of AZ91 alloy. Ca had a greater effect on the mechanical properties of AZ91 extruded alloy than Si. At room temperature, the yield strength, tensile strength and elongation of Mg-9Al-Zn-0.5RE-Si extruded alloy were 254 MPa, 306 MPa and 7.0%, respectively. However, the yield strength, tensile strength and elongation of Mg-9Al-Zn-0.5RE-0.5Ca extruded alloy were 308 MPa, 330 MPa and 7.1%, respectively. The mechanical properties of Mg-9Al-Zn-0.5RE-0.5Ca-0.5Si extruded alloy at room temperature were the best, and its yield strength,tensile strength and elongation were 351 MPa, 383 MPa and 7.4%, respectively. It indicated that the strength and plasticity of AZ91 extruded alloy could be improved simultaneously through the synergistic action of Ca and Si. At 150 ℃ and 200 ℃,Mg-9Al-Zn-0.5RE-0.5Ca-0.5Si alloy still had the best mechanical properties. At 150 ℃, the yield strength, tensile strength and elongation were 174 MPa, 225 MPa and 31.8% respectively. At 200 ℃, the yield strength, tensile strength and elongation were 136 MPa, 153 MPa and 49% respectively. After extrusion, ■ and ■ textures parallel to the extrusion direction were formed in the alloy. After 360 ℃ hot extrusion, the tensile properties of the alloy can be significantly improved due to dynamic precipitation, dynamic recrystallization and texture. At room temperature, 150 ℃ and 200 ℃, the mechanical properties of Mg-9Al-Zn-0.5RE-0.5Ca-0.5Si are the best, indicating that the addition of Ca, Si and La/Ce mixed rare earth elements at the same time is beneficial to improving the heat resistance of AZ91 alloy.

镁合金是有益的轻量化材料,由于弹性模量低于铝合金,导致车体刚度下降.车体边梁是影响车体的关键承载部位,提高其刚度可有效降低车体挠度.提取镁合金列车侧顶的边界条件,以侧顶挠度下降幅度最大部分为子模型,通过子模型与整车模型位移对比验证子模型准确性;采用多节点灵敏度分析方法筛选最佳设计变量,进行尺寸优化;随后采用hypermorph网格变形技术,实现边梁截面形状优化.结果表明:采用子模型进行尺寸-形状优化,可有效缩短计算时间,优化后侧顶最大垂向挠度减少10.68％,最大应力下降31.76％.

基于轨道车辆运行线路的基本要求,以国际通用设计标准为依据,介绍了轨道车辆贯通道系统的设计方案.通过对车辆参数和线路运行条件的综合分析,阐述贯通道系统的接口方案设计和选型依据,保证贯通道系统性能可靠,易于维护,同时满足线路及运营的所有工况要求.

地铁车辆结构形式和功能配置的多样化,给地铁列车互联互通带来一定困难.针对目前我国地铁车辆技术规格书要求的多样性开展调研分析.根据调研结果,修改完善当前地铁车辆技术条件,编制系列化中国标准地铁列车4种车型技术规格书.分析技术规格书中车体技术条件与既有地铁列车执行标准及规范的主要差异,为标准化地铁列车研制项目技术创新成果的推广提供参考.

本文主要介绍伊朗设拉子地铁车辆轻量化碳钢车体设计.主要介绍碳钢车体钢结构的组成及特点.