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城市立交工程中,曲线梁桥由于弯矩、扭矩的共同作用,受力较为复杂。针对某互通式立交工程中3种曲率半径(30、60、90m)的曲线桥梁,设置不同支座预偏心,对主梁的受力性能进行分析。结果表明:合理的支座预偏心可以改善桥梁的受力性能,优化桥梁设计。 相似文献
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由于曲率的影响,曲线箱梁桥容易产生弯扭耦合作用,对于采用单柱式点铰支座的曲线箱梁桥,如果支座或偏心大小设置不当,容易引发支座脱空、梁体沿径向向外偏移、向外翻转的工程病害。实践证明:为点铰式支座设置适当的偏向箱梁剪力中心线外侧的预偏心距,可以有效地降低曲线梁的内扭矩和改善曲线箱梁桥抗扭墩的受力状况。采用Powell算法计算了曲线箱梁桥点铰式支座的预偏心距,计算结果表明可以收到较好的效果,该方法可以集成到曲线箱梁桥的设计程序当中,将具有更大的应用价值。 相似文献
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小半径连续弯梁桥中支点设独柱墩时,往曲线外侧方向设置预偏心,将极大改善因弯扭耦合作用产生的主梁扭矩以及内、侧支座的不均衡反力。结合工程实例,以主梁扭矩分布的均匀程度、内外侧支反力的均衡程度等作为指标,获得预偏心的合理设计值。有关经验供相关专业设计人员参考。 相似文献
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近年来因车辆超载导致独柱墩曲线梁桥垮塌事故频发,对既有独柱墩曲线梁桥进行安全评估与加固成为研究热点。该文以某高速公路独柱墩曲线梁桥为例,首先应用Midas/Civil建立有限元模型,采用支座反力法、稳定系数法计算获得的抗倾覆稳定系数分别为2.0、1.76,均不满足规范(大于2.5)要求;接着分析了支座预偏心对曲线梁桥抗倾覆稳定性的影响。结果表明:该桥最佳预偏心值为11cm,设置支座预偏心能一定程度提高桥梁抗倾覆稳定性;最后提出一种独柱墩增设钢结构盖梁及支座加固设计方案,其抗倾覆稳定系数为3.5,加固后支座不会出现脱空现象,钢结构盖梁和增设钢结构盖梁后桥墩偏心受压承载力验算结果均符合现行规范要求,研究成果可供类似独柱墩曲线梁桥加固设计参考借鉴。 相似文献
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独柱支承曲线连续梁桥预偏心距设计 总被引:3,自引:1,他引:2
针对独柱支承连续曲线梁桥的预偏心距设计存在的问题,采用数值模拟方法分别对不同曲率半径的独柱支承曲线连续梁桥的中支点合理预偏心距设置问题进行了研究。独柱支承曲线连续梁桥中支点预偏心距的设计不仅要考虑主梁扭矩的分布,同时还要考虑主梁的扭转角位移、主梁端部支承反力是否受拉等因素。不同曲率半径的独柱支承曲线连续梁桥的中支点预偏心距确定时,所考虑因素的侧重点也不相同。 相似文献
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《JSAE Review》2002,23(1):83-87
Viscous coupling units (VCUs) are widely used in full-time four-wheel drive vehicles (full-time 4WDs) as a differential limiting device. A VCU must provide optimized torque transfer characteristics both for maximum traction and for maneuverability during tight cornering. We analyzed the effect of VCU torque transfer characteristics on the development of a “tight corner braking phenomenon”. The results of this analysis were verified to have a high correlation with experimental data, and have enabled us to determine the optimum torque transfer characteristics which allow for minimization of the tight corner braking phenomenon for any given VCU design. 相似文献
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This paper presents a new optimization method to obtain the structural design of permanent magnet motor which can reduce the mechanical vibration. The optimization problem is formulated to minimize a multi-objective function including the mean compliance of the whole stator for maximizing the stiffness under the magnetic force and the torque ripple by aligning torque profiles to a constant target value for maximizing the magnetic performance, with constraint for material usage. The level set function is introduced for representing the structural boundaries and calculating the material properties. A coupled magneto-mechanical analysis is performed to verify the vibration characteristic of the motor system and obtain the design sensitivities. To confirm the usefulness of the proposed design method and to obtain the optimum structural design for low vibration motor, a design example of 20 kW interior permanent magnet motor developed for the power train of a hybrid electric vehicle is provided. 相似文献
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汽车发动机性能指标的优选方法 总被引:1,自引:0,他引:1
本文提出了一种优选汽车发动机性能指标的方法,即在给定汽车底盘参数,整车性能和汽车车行驶条件下,应用本文提出的方法可以优选汽车发动机最大功率及其相应转速,最大扭矩及其相应转速和发动机排量,这为汽车设计或改进设计时发动机的选型提供依据。 相似文献
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玻璃刮水器是汽车的重要零部件之一,本文介绍刮水器电动机的类型,包括按照磁场结构分类、按照控制方式分类、按照电动机负荷扭矩分类;分析了刮水器各种功能的实现,包括高速刮刷的实现、低速刮刷的实现、间歇刮刷的实现、雨量传感器感应刮刷的实现;研究了刮水电动机在乘用车系统的应用实例。本文力求通过对比分析不同的电动机和不同功能的组合,达到玻璃刮水器电动机系统的最优设计。 相似文献
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《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2012,50(3):175-198
A mathematical model for the in-plane dynamic analysis of motorcycles is presented and the performance during an emergency braking manoeuvre is analysed. The effects of braking torque amplitude and time constant are discussed and the problems of lock-up and loss of contact of the rear wheel are highlighted. The suspensions' vibrations during braking are analysed by means of modal analysis. An optimisation method is developed in order to find the braking torque and the suspension parameters that minimise the stopping distance. The method takes the complete dynamic behaviour of the vehicle during braking into account and is based on a non-derivative minimisation algorithm. Several results are presented that show the possibility of shortening the stopping distance by optimum design of one or both of the suspensions. 相似文献
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Vittore Cossalter Alberto Doria Roberto Lot 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2000,34(3):175-198
A mathematical model for the in-plane dynamic analysis of motorcycles is presented and the performance during an emergency braking manoeuvre is analysed. The effects of braking torque amplitude and time constant are discussed and the problems of lock-up and loss of contact of the rear wheel are highlighted. The suspensions' vibrations during braking are analysed by means of modal analysis. An optimisation method is developed in order to find the braking torque and the suspension parameters that minimise the stopping distance. The method takes the complete dynamic behaviour of the vehicle during braking into account and is based on a non-derivative minimisation algorithm. Several results are presented that show the possibility of shortening the stopping distance by optimum design of one or both of the suspensions. 相似文献
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基于虚拟仪器技术,借助于传感器、信号调理器和数据采集卡等硬件,应用NILabVIEW软件编制了振动数据采集与处理程序,研制了发动机振动测试系统。利用该系统进行了发动机缸盖螺栓拧紧力矩与机体振动量关系的振动测试,得到了机体振动量较小时对应的螺栓最佳拧紧力矩范围,且与发动机生产厂家推荐的数据比较吻合,从而验证了所研制振动测试系统的可行性和正确性。 相似文献
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M. C. Good 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》1979,8(4):253-285
Compared with the fixed-control case, relatively few studies of the effects on handling quality of the nature of the free-control response of an automobile to steering torque inputs have been reported. Prior to reviewing these studies, an attempt is made in this paper to provide a conceptual framework for assessing the results, by drawing on analytical and experimental work concerned with manual control in closed-loop tracking systems. Application of these ideas to the automobile shows that a fixed-control driver strategy is required where precise path control is necessary. Less demanding situations would allow a free-control driving mode. Steering task performance is found to be relatively insensitive to free-control vehicle responses. However, drivers exhibit clear preferences for certain ranges of steering torque gradient, and for rapid responses of steering wheel angle to torque inputs. Vehicle handling variables interact strongly in their effect on driver opinion. For example, the optimum steering torque gradient (in N m/G) decreases, and the optimum steering “stiffness” (in N m/rad) increases, as the fixed-control response sensitivity increases. Within fairly wide ranges, the damping of the free-control oscillatory mode has little effect on handling quality. 相似文献