Impact of inerter nonlinearities on vehicle suspension control

This paper discusses the nonlinear properties of inerters and their impact on vehicle suspension control. The inerter was recently introduced as an ideal mechanical two-terminal element, which is a substitute for the mass element, where the applied force is proportional to the relative acceleration across the terminals. Until now, ideal inerters have been applied to vehicle, motorcycle and train suspension systems, in which significant performance improvement was achieved. However, due to the mechanical construction, some nonlinear properties of the existing mechanical models of inerters are noted. This paper investigates the inerter nonlinearities, including friction, backlash and the elastic effect, and their influence on vehicle suspension performance. A testing platform is also built to verify the nonlinear properties of the inerter model.     

基于正交基神经网络的热敏电阻温度传感器非线性补偿方法

针对热敏电阻温度传感器应用中存在的非线性问题，提出了应用正交基（0BF）神经网络进行非线性补偿的方法。研究结果表明，OBF神经网络非线性补偿算法具有补偿精度高、计算量小的优点，因而是一种有效的非线性补偿方法。     

Nonlinear feedforward–feedback control of clutch-to-clutch shift technique

To improve the shift quality of the vehicle with clutch-to-clutch gear shifts, a nonlinear feedforward–feedback control scheme is proposed for clutch slip control during the shift inertia phase. The feedforward control is designed based on flatness in consideration of the system nonlinearities, and the linear feedback control is given to accommodate the model errors and the disturbances. Lookup tables, which are widely used to represent complex nonlinear characteristics of powertrain systems, appear in their original form in the designed feedforward controller, while the linear feedback controller is calculated through linear matrix inequalities such that the control system is robust against the parameter uncertainties. Finally, the designed controller is tested on an AMESim powertrain simulation model, which contains a time-variant model of clutch actuators.     

Fault-tolerant control of heavy-haul trains

The fault-tolerant control (FTC) of heavy-haul trains is discussed on the basis of the speed regulation proposed in previous works. The fault modes of trains are assumed and the corresponding fault detection and isolation (FDI) are studied. The FDI of sensor faults is based on a geometric approach for residual generators. The FDI of a braking system is based on the observation of the steady-state speed. From the difference of the steady-state speeds between the fault system and the faultless system, one can get fault information. Simulation tests were conducted on the suitability of the FDIs and the redesigned speed regulators. It is shown that the proposed FTC does not explicitly worsen the performance of the speed regulator in the case of a faultless system, while it obviously improves the performance of the speed regulator in the case of a faulty system.     

大兴路立交匝道桥震害原因分析及修复方案

汶川地震中,位于汶川地震烈度较低区域的西安市大兴路立交发生了较大的破坏。为分析该桥震害原因,采用MIDAS Civil软件建立该桥有限元模型,运用非线性时程方法分析结构的地震响应。分析结果表明:该桥较多滑动支座的支承体系降低了其对主梁变位的约束能力;场地地震动的长周期特性使梁体与支座产生滑移后自振周期延长,导致结构从地震波中吸收了较多能量,加剧了震害。对比2种支承体系修复方案的抗震性能后,推荐支承体系修复方案采用四氟滑板橡胶支座(边墩)、普通板式橡胶支座(中墩)的方案。     

非线性负荷及其对电能质量的影响分析

介绍非线性负荷的种类及用电特性,分析非线性负荷对电能质量的影响,并搭建电路进行仿真。     

拉索非线性振动参数敏感性分析及其频率区间估计

为准确把握拉索的动力学规律并指导工程应用,以拉索非线性振动理论(拉索自振频率的摄动法公式)为基础,以工程中常用的典型拉索为例,对拉索非线性自振频率的边界条件效应、参数敏感性以及区间估计方法进行研究.研究结果表明:拉索的边界条件效应随拉索长度、索力以及频率阶次的不同而不同;索力、线密度、弦长、抗弯刚度4个参数对于拉索各阶自振频率在影响程度、影响方式方面均存在显著差异,总体而言,自振频率偏差与索力和抗弯刚度2个参数的偏差成正比,与线密度和弦长2个参数的偏差成反比;根据拉索参数的概率统计特征能够获得拉索自振频率的区间估计.     

高架桥中异形桥墩的三维仿真分析

城市桥梁建筑景观需要使许多高架桥桥墩设计成异形构件,而一般的梁单元方法只能近似分析其力学性能.以天津东旭路桥的异形桥墩为工程实例,利用ANSYS的三维实体单元,正确仿真异形桥墩的整体结构,分析其在恒载和组合工况作用下的三维应力分布情况;并利用ANSYS的钢筋混凝土非线性分析功能,计算桥墩混凝土开裂区的钢筋应力,分析混凝...     

模态静力推覆分析方法在桥梁结构中的应用

静力推覆分析是一种计算结构非线性响应的简化分析方法,然而标准的静力推覆分析方法不能计人高阶振型的贡献,难以应用到大跨度的桥梁结构中.有学者提出的模态静力推覆分析方法在计算结构的非线性响应时考虑了高阶振型的影响,且仍具有推覆分析方法计算量小的优点.该文使用模态静力推覆分析方法计算一座实际桥梁结构的非线性反应,并与标准的推...     

曲塔混合梁斜拉桥的非线性稳定分析

介绍了曲塔混合梁斜拉桥的结构形式和稳定性分析方法。根据曲塔混合梁斜拉桥的受力特点,建立斜拉桥施工阶段几何非线性分析的有限元模型,完成了斜拉桥施工过程的仿真分析。在考虑了几何非线性和材料非线性效应的基础上,进行斜拉桥施工阶段和成桥状态的稳定性分析。结果表明,几何非线性对结构整体稳定性影响显著,在考虑几何非线性效应的基础上,材料非线性对稳定性的影响可忽略不计。