高寒地区后张箱梁纵向裂缝成因分析、验证及处理

为研究高寒地区后张预应力混凝土箱梁的纵向裂缝成因及损伤机理,采用钻孔法检测结构内部损伤特征,并利用A baqus有限元软件分析孔道冻胀过程中的混凝土损伤行为.结果表明:低温环境下预应力孔道内水泥浆水化反应不充分、泌水受冻结冰膨胀是梁体混凝土沿纵向开裂的主要原因.冻胀过程中,孔道边缘混凝土率先受损,随后腹板内、外表面同时...     

东风日产颐达车制动时有异响

故障现象一辆2006年东风日产颐达轿车,配置1．6L发动机和4速自动变速器,累计行驶里程为7．5万km,刚开始制动时有异响,并且有制动跑偏的现象,过几天仪表盘上的ABS指示灯常亮。     

一汽奔腾B50车发动机故障灯异常点亮

正故障现象一辆2009年产一汽奔腾B50车,搭载型号为LF的2.0 L发动机,累计行驶里程约为12.8万km,因车辆行驶过程中发动机故障灯点亮而进厂维修。故障诊断接车后试车验证故障现象,故障现象确实存在,发动机故障灯点亮,且伴随发动机怠速轻微抖动和发动机加速无力的现象。连接故障检测仪读取故障代码,发动机控制单元内存储有故障代码"P2187怠速时系统混合比过稀(第1排)",记录并尝试清除故障代码,故障代     

宝马X5车刮水器工作异常 转向沉重

故障现象一辆刚刚行驶了33 km的新款宝马X5-E70LCI汽车(发动机型号为N55),当客户以80 km/h的速度开着刚刚提到的新车去上牌时,在途中突然发觉从未启用的雨刮片在前风窗玻璃上来回工作,同时转向变得沉重,组合仪表中有多个黄色指示灯亮起,以及多个红色指示灯交替闪烁,并且中央显示屏中出现以下警告信息:主动转向控制失效,转向性能会改变,转向盘可能不对中,可     

Rigid-flex coupling modeling and simulation on multistage gear transmission system

As multistage gear transmission systems are complex and precise, the flexibility of shaft can influence the dynamic response of system. In order to study dynamic response of the system, we build the rigid model of gear system and the finite element model of the gear shaft. The rigid-flex coupling model is established with the virtual prototype technology, and a contrast between rigid model and rigid-flex coupling model is constructed.With these methods, the dynamic responses with different rotation speeds and different loading magnitudes are examined. We also analyze the influence of shaft flexibility, rotation speeds and loading magnitudes on the vibration characteristics of gear transmission systems.