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41.
大跨度悬索管道桥桥面窄,宽跨比小,结构十分轻柔,结构参数的改变对其动力特性有较大的影响。以川气东送野山河悬索跨越工程为例,采用大型有限元分析软件ANSYS10.0分析了风缆预张力和风缆面与水平面夹角变化对该悬索管道桥动力特性的影响。研究表明,提高风缆预张力和选取适当的风缆与水平面的夹角能有效地提高全桥结构刚度。 相似文献
42.
基于交通效率、安全和特定交通组成的纵坡合理坡长 总被引:1,自引:0,他引:1
由于用地及地形、地质等限制,纵坡常被迫用到规范推荐的限制值,而我国《城市道路设计规范》(CJJ37-90)对5%以下的纵坡坡长限制没有进行规定,如何确定此类纵坡的合理坡长直接影响到路段交通安全、效率、工程经济等。通过对已有的纵坡坡长限制研究成果整理分析,提出运用汽车动力学进行坡长计算时,应该考虑汽车坡中换档的情况,并引入适合车型的概念,建议根据道路交通组成的实际情况确定坡长。分析坡长对驾驶员心率增长率、制动鼓温度、事故率的影响,分别确定各影响因素下的最大坡长。最后提出综合考虑交通效率和安全的坡长限制确定方法,并在某大纵坡路段的纵坡论证中进行了应用。 相似文献
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汽车非线性悬架的混沌研究 总被引:2,自引:0,他引:2
采用基于实测数据建立的非线性悬架模型,分析了汽车悬架中的非线性弹簧力和阻尼力,对非线性悬架系统的混沌运动进行了研究.在单频正弦路面、拟周期路面以及随机路面激励情况下,仿真计算得到了系统的响应.分析各激励下系统的相轨迹、庞加莱(Poincaré)截面、时间历程曲线、功率谱图及李亚谱诺夫(Lyapunov)指数图,结果表明非线性悬架系统中存在混沌现象. 相似文献
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文章采用计算流体力学(CFD)方法,结合SST k-棕湍流模型,对低质量比柱体进行两自由度涡激振动数值模拟,得到了柱体升力、曳力系数的时程曲线,并观察了柱体进入锁振状态的幅值变化,研究了不同截面形式柱体在外流速处于0.1-1.0 m/s范围内的振动响应。将圆柱体在不同流速下两向振动的CFD数值模拟与实验数据进行比较,得到了较为满意的结果。通过分析不同截面柱体在不同外流速下的振动幅值发现,带有抑振装置的柱体截面形式能够有效地减小涡激振动,其中,板状截面柱体抑振效果较好。 相似文献
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Vinicius F. Dal Poggetto 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(2):191-209
Many researches have been conducted in the area of control applied to vehicle dynamics, aiming at reducing the possibility of the occurrence of the type of accident known as rollover. In this research, based on a common nonlinear model and its linearisation, a method for properly selecting matrices for solving the Riccati equation considering different speeds was proposed. The method showed in which ways speed really influences the choice of controller gains. By developing the dynamic equations for the yaw- and roll-coupled motions and modelling of controllers and state observers, it is possible to compare the efficacy of this control strategy using both linear and nonlinear simulations using Matlab. Significant results were obtained regarding the reduction of the rollover coefficient for a double-lane change manoeuvre at different speeds, thus indicating advantages of using this controller in practical cases. 相似文献
49.
J.A. Mohrfeld-Halterman 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(1):124-136
Presented in this paper is a procedure to develop a high fidelity quasi steady-state aerodynamic model for use in race car vehicle dynamic simulations. Developed to fit quasi steady-state wind tunnel data, the aerodynamic model is regressed against three independent variables: front ground clearance, rear ride height, and yaw angle. An initial dual range model is presented and then further refined to reduce the model complexity while maintaining a high level of predictive accuracy. The model complexity reduction decreases the required amount of wind tunnel data thereby reducing wind tunnel testing time and cost. The quasi steady-state aerodynamic model for the pitch moment degree of freedom is systematically developed in this paper. This same procedure can be extended to the other five aerodynamic degrees of freedom to develop a complete six degree of freedom quasi steady-state aerodynamic model for any vehicle. 相似文献
50.
Jong-Boo Han Hyung-Suk Han Sung-Soo Kim Seok-Jo Yang 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(3):370-385
Normally, Maglev (magnetic levitation) vehicles run on elevated guideways. The elevated guideway must satisfy various load conditions of the vehicle, and has to be designed to ensure ride quality, while ensuring that the levitation stability of the vehicle is not affected by the deflection of the guideway. However, because the elevated guideways of Maglev vehicles in South Korea and other countries fabricated so far have been based on over-conservative design criteria, the size of the structures has increased. Further, from the cost perspective, they are unfavourable when compared with other light rail transits such as monorail, rubber wheel, and steel wheel automatic guided transit. Therefore, a slender guideway that does have an adverse effect on the levitation stability of the vehicle is required through optimisation of design criteria. In this study, to predict the effect of various design parameters of the guideway on the dynamic behaviour of the vehicle, simulations were carried out using a dynamics model similar to the actual vehicle and guideway, and a limiting value of deflection ratio of the slender guideway to ensure levitation control is proposed. A guideway that meets the requirement as per the proposed limit for deflection ratio was designed and fabricated, and through a driving test of the vehicle, the validity of the slender guideway was verified. From the results, it was confirmed that although some increase in airgap and cabin acceleration was observed with the proposed slender guideway when compared with the conventional guideway, there was no notable adverse effect on the levitation stability and ride quality of the vehicle. Therefore, it can be inferred that the results of this study will become the basis for establishing design criteria for slender guideways of Maglev vehicles in future. 相似文献