共查询到19条相似文献，搜索用时 312 毫秒
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车辆与桥梁结构的动力相互作用是一个非常复杂的课题,它受许多随机因素的影响。车辆对桥梁作用的动荷载既受车辆结构参数、运行速度、载重和质量分布的影响,还受桥面不平度的影响,同时与轮胎和桥面的接触关系密切相关。另一方面,车辆的振动不仅与车辆参数有关,还受桥梁振动及桥面不平整度影响。由于车辆振动与桥梁振动两者之间的相互影响,加之桥梁上车辆的位置及车辆数量、类型等在不断变化,导致问题异常复杂,形成一个时变系统动力学问题。 相似文献
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在总结国内外车轮多边形研究的基础上,调查了高速动车组车轮多边形情况,并对测试车轮的多边形数据进行统计分析,从车轮多边形与运行速度、运行线路条件,查找容易产生车轮多边形的影响因素。研究车轮多边形对车辆振动的影响,研究降低车轮多边形对乘坐舒适性、转向架可靠性造成的影响,对比不同多边形幅值与车辆振动的对应关系;从抑制多边形角度进行了镟修工艺优化,通过控制驱动轮径跳、实施双刀镟修等手段消除运营过程中出现的多边形;研究调整车轮材料、车轮实施滚压等方式,增加车轮强度,降低车轮磨耗,延缓多边形发展;针对车轮多边形的成因较多无法彻底消除车轮非圆化的现状,可利用轨道检测装置检测车辆车轮状态,在车轮多边形影响车辆振动之前及时进行维护。 相似文献
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谈汽车行驶平顺性的评价分析 总被引：1，自引：0，他引：1
汽车是一个复杂的多质量振动系统,其车身通过车架的弹性元件与车桥连接,而车桥又通过弹性轮胎与道路接触,其他如发动机、驾驶室等,也是以橡皮垫固定于车架。在激振力作用下,如道路不平而引起的冲击和加速、减速时的惯性力,以及发动机与传动轴振动等,系统将发生复杂的振动,对乘员的生理反应和所远货物的完整性,均会产生不利的影响。 相似文献
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为保证汽车安全行驶,要对汽车车辆上各种配件的可靠性进行严格的检测。刹车制动毂是刹车制动系统中的关键部件之一,它在汽车行驶中和刹车制动过程中受振动和冲击最严重,因此对它的可靠性检测就显得更为重要。重点介绍了转毂试验台的结构、原理、工作过程及测试程序。在转毂试验台上模拟了汽车的各种动态工况,测试了防抱死制动系统的性能。试验表明,该转毂试验台及其测试程序能满足防抱死制动系统性能的测试要求。 相似文献
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桥梁与车辆的耦合振动方程为时变系数微分方程,用解析的方法求解这类问题有很大的局限性,解决这类问题的最为有效的工具之一是数值方法中的有限单元法.对移动衙载这种简化模型在时程积分时采用了精细积分法,为了保持精细时程积分法的高精度,对动力方程中的非齐次项进行离散计算时选用了积分精度较高的科茨积分格式,对于Euler-Bernouili梁单元采用二节点的Hermite插值函数,模拟了移动常量荷载、移动简谐荷载作用下的等截面和变截面简支梁桥模型的振动情况,并与解析的结果及一些其它的数值解法进行了对比,显示了采用精细时程积分时对动力响应过程的数值模拟的高精度. 相似文献
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钢纤维混凝土具有优异的抗裂性、抗冲击韧性和耐疲劳极限,对于以承受车轮荷载疲劳和冲击作用为主的桥面结构,钢纤维混凝土桥面是一种良好的结构形式。本文结合G205新开河桥工程实例对钢纤维混凝土性能、技术要求、施工工艺等进行了阐述。 相似文献
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车辆对不平整路面的随机动压力分析 总被引：1，自引：0，他引：1
采用双自由度四分之一车辆模型,以路面不平整和车辆发动机振动为激励,运用随机过程理论分析了车辆对不平整路面的随机动压力,得到了车辆动压系数的概率分布以及最大动压系数与路面不平整度、车速、悬挂质量以及悬挂系统与非悬挂系统特性之间的关系。算例分析表明,引起车辆振动的路面不平整波形的频率范围主要集中在0.04～2.0之间,最大动压系数随路面不平整度、车速、悬挂与非悬挂系统刚度的增大而增大,随着悬挂质量以及悬挂系统阻尼的增大而减少,而轮胎阻尼对车辆动荷载的影响并不显著。 相似文献
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结合某连续梁桥的孔道摩阻损失试验,介绍了预应力摩阻试验的内容和方法,并利用最小二乘法计算出合理的孔道摩阻系数和偏差系数值,其结果表明试验原理与计算方法是有效的,可以为预应力张拉质量提供正确的依据。 相似文献
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在滑模摊铺水泥混凝土路面施工中,应创造条件使路面板与桥(涵)面钢筋混凝土铺装层连续摊铺。采用滑模摊铺机连续不问断摊铺桥(涵)面铺装层、桥头双层钢筋混凝土搭板和胀缝,可以提高桥面铺装的设计施工质量,延长其使用年限,减少桥面返修对交通带来的不利影响。 相似文献
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Rami Faraj Łukasz Jankowski Cezary Graczykowski Jan Holnicki-Szulc 《Journal of The Franklin Institute》2019,356(14):7855-7872
This paper investigates an application of a ball-screw inerter for mitigation of impact loadings. The problem of impact absorption is to provide a minimum reaction force that optimally decelerates and eventually stops an impacting object within the available absorber stroke. It significantly differs from vibration mitigation problems which are typical application of inerters. The paper demonstrates that the optimum absorption can be achieved by fully passive means. For known values of the object mass and inerter parameters, the obtained solution is independent of the impact velocity. The optimum passive absorption is achieved by employing a variable thread lead. As a result, two force components emerge, the typical inertance-related force and a damping-like term, and sum up to provide the optimum constant deceleration force. This result is relatively unique: conventional absorbers do not provide a constant force even with complex active control systems. Finally, an optimization problem is formulated to reduce the influence of process uncertainties (range of possible mass values, unknown friction). The results are verified and analyzed in a numerical example. 相似文献
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《Journal of The Franklin Institute》2023,360(11):7269-7293
The interferences and drivers' maloperations are important factors affecting vehicle driving safety. This paper investigates the problem of authority allocation to weaken the impact of interferences and drivers’ maloperations on the shared steering control system. Based on the parallel framework of the shared steering control system, an extended framework including the upper level and the lower lever is proposed. The lower lever is used to realize the shared steering control, which includes the driver model, trajectory tracking controller and vehicle model. To improve the robustness of the system, the uncertainty of vehicle dynamics parameters is considered in the trajectory tracking controller, including tire cornering stiffness and longitudinal velocity. The upper level is used to calculate the authority level of the driver and controller required by the lower lever, which consists of an authority dynamic allocation model and an authority allocation decision strategy. The role of the authority dynamic allocation model is to calculate the reference allocation level of the driver and controller dynamically. When the driver's operation and vehicle working states are trustworthy, the reference allocation levels of the driver and controller will be followed. Conversely, a decision result will be gained by the authority allocation decision strategy to replace the reference allocation levels, and the sum of the authority levels of the driver and the automation will not be fixed as 1. The simulation results show that the proposed approach can effectively improve vehicle driving safety, anti-interference and reliability, and can effectively reduce the impact of crosswind and driver's maloperation on vehicle safety, and alleviate the driver's operation load. 相似文献
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摩擦学特性对发动机功效的发挥起着重要作用,对其进行分析和探讨有助于改善发动机工作性能。基于斜盘发动机基本结构,建立了其内部组件的球滚动摩擦模型和柱滚动摩擦模型,并推导了相应的滚动摩擦力和滚动摩擦系数公式。然后结合某斜盘发动机具体参数,分别计算了球滚动摩擦力、摩擦系数和柱滚动摩擦力、摩擦系数,通过对比,认为柱滚动摩擦力、摩擦系数远小于球滚动摩擦力、摩擦系数。最后分析了摩擦生热、高温环境对发动机摩擦性能的影响,并指出了下一步研究的方向。 相似文献
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本文结合桥面铺装工程的实例,对桥面铺装结构和材料的设计进行了探讨。以交通荷载条件,桥梁结构型式为基础,认为提高沥青技术指标,完善防水粘结层和沥青混合料结构型式,可大大提高沥青混合料的热稳定性,提高其自身的强度。本文对同类工程的设计提供了理论和实践的支持,具有一定的参考价值。 相似文献
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Reza Langari 《Journal of The Franklin Institute》2018,355(10):4315-4335
Modern vehicles are equipped with a growing number of electronic devices, which significantly improve the driving experience. However, the complicated architecture of electronic systems also increases the difficulty of fault diagnosis since process models are often unavailable. This paper presents a novel detection and mitigation system for vehicle related anomalies originating in unintended acceleration (UA), which has become one of the most complained-about vehicle problems in recent history. The detection system consists of several neural network-based models, which are created by analyzing historical vehicle data at specific moments such as acceleration peaks and gear shifting. These data-driven models describe the boundary of normal vehicle behavior in the data space. A priori knowledge of complete vehicle structures is not necessary for building them. The detection system combines these models to decide if a UA event has occurred. When a UA event is detected, a mitigation system cuts the engine power and adjusts the braking force accordingly. The whole system was validated in the Simulink/dSPACE environment. UA errors were simulated so that they occurred randomly when human subjects drove virtual cars in a simulated environment. Random noise of sensors were also considered and incorporated to add realism. Various traffic scenarios were included in tests. Test results show that the integrated system is capable of detecting UA in one second with high accuracy and reducing the risk of accidents. 相似文献
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I. Opatowski 《Journal of The Franklin Institute》1942,234(3):239-249
The bases for a theoretical study of wear by friction were given by Th. Reye. Starting from the obvious assumption that the more work done by the friction forces the more material is removed from the worn surface, he was able first to investigate theoretically the mechanics of different types of bearings. The importance of wear by friction is in some mechanical organs, particularly brakes, so great, that the ideas which Reye published 80 years ago still form today the theoretical basis for their design. The present paper is an attempt to go further in these investigations by taking into account two factors which up to now have been neglected: (1) the elastic deformation of the body subjected to wear and (2) the continuous change of its shape in consequence of the wear. The study, which is carried out in a case where the wear effect is particularly evident, the case of brakes, leads to formulas for the determination of the working features of this organ. It explains also in a very clear manner why a certain geometric position of the braking organs is necessary in order to obtain a progressive braking action and why this becomes worse as the wear goes on. 相似文献
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《Journal of The Franklin Institute》2022,359(16):8497-8521
In order to improve the response speed and control precision of the braking system with parameters uncertainty and nonlinear friction, a braking-by-wire system based on the electromagnetic direct-drive valve and a novel cascade control algorithm was proposed in this paper. An electromagnetic linear actuator directly drives the valve spool and rapidly adjusts the pressure of braking wheel cylinders. A dynamic model of electromagnetic direct-drive valve considering improved LuGre dynamic friction is established. A novel cascade control algorithm with an outside loop pressure fuzzy controller and an inside loop electromagnetic direct-drive valve position controller was proposed. An adaptive integral robust inside loop controller is designed by combining friction compensation adaptive control law, linear feedback, and integral robust control. The uncertainty parameters and the friction state are estimated online. The stability of the cascade controller is proved by the Lyapunov method. Then a multi-objective opitimizemization design method of control parameters is proposed, which combines a multi-objective game theory and a technique for order preference by similarity to ideal solution (TOPSIS) based on entropy weight. The results show that the pressurization time of cascade control is less than 0.09 s under the 15 MPa step target signal. The control precision is improved effectively by the cascade controller under the ARTEMIS condition. 相似文献