斜拉桥索塔环向预应力摩阻损失试验研究

文章依托江苏省如皋市长青沙二桥(斜拉桥)工程项目,通过预应力张拉试验,现场实测了U形预应力筋的摩阻损失,并采用最小二乘法拟合求得孔道摩阻系数和偏差系数,验证了此种预应力结构的合理性。     

Effect of wheel-slip prevention based on sliding mode control theory for railway vehicles

It is important to consider the robustness when designing brake control systems, because of the model's uncertainties that result from the nonlinear characteristics of wheel-to-rail adhesion forces and brake material friction coefficients. This paper presents the experimental results from the new wheel-slip prevention control using nonlinear robust control theory. The authors performed experiments for the proposed wheel-slip prevention control to compare it with the conventional control laws. The experimental results proved the comparative effectiveness of the proposed control and showed high brake performance under nonlinear characteristics of brake dynamics.     

ZD（J）9新型电动转辙机摩擦联结器研究

对ZD（J）9新型电动转辙机摩擦联结器的作用及设计思路、计算过程作了简要的阐述,特别对其性能进行了分析。     

Cu基金属陶瓷摩擦材料的成本优化研究

为降低金属陶瓷摩擦材料的制造成本，介绍了Cu基金属陶瓷摩擦材料成本优化方案，并研究了优化方案对Cu基金属陶瓷摩擦材料性能的影响。研究结果表明，Fe可替代Cu用以降低成本，但Fe的含量不应超过20％；可选用低纯度的天然鳞片状石墨作为润滑组元以降低成本，但其纯度不应低于90％；通过合理选择烧结工艺参数，在保证钢背与金属陶瓷摩擦材料的结合强度不低于金属陶瓷摩擦材料自身的抗剪强度的前提下，可以用“平板”状钢背代替“碗状”钢背来降低成本。     

基层间接触状态对沥青路面结构受力的影响分析

文章基于有限元接触理论,建立考虑层间粘结状态的大厚度半刚性基层沥青路面结构有限元分析模型,模拟分析不同基层间摩擦系数条件下的路表弯沉变化规律、面层层底弯拉应力变化规律以及上下基层底部弯拉应力变化规律。结果表明:在基层间粘结接触较弱的情况下,完全假设各层间为连续状态分析得到的路面弯沉值及应力值会与考虑层间摩擦时的计算值存在较大的差异,对沥青路面结构受力分析合理性的影响是不可忽略的;只有基层间摩擦系数大到一定程度后,大厚度半刚性基层沥青路面结构才能近似等效为层间连续,在基层间摩擦系数较小的情况下,可采用有限元接触模型进行大厚度半刚性基层沥青路面结构的设计分析。     

Experimental and numerical studies on dynamic stress and curvature in steel tube umbilicals

The present paper addresses the stresses in dynamic steel tube umbilicals at the platform hang-off exposed to large motions corresponding to an extreme storm condition. Experimental tests were carried out by mounting fibre-optic Braggs inside steel tubes of a 9 m long umbilical specimen. Then the specimen was exposed to constant tension and dynamic curvature by means of a bellmouth and the stresses were measured. Realizing that the geometry of the umbilical cross section was too complex to apply full 3D modeling, a beam and penalty contact modeling procedure was applied to describe the extreme stress behavior. Then a simplified method was proposed to determine the contact stiffness which was further validated by full scale umbilical axial stiffness testing. As hoop contact interfaces between steel tubes and separation fillers were observed in the test specimen, a tailor-made contact element was formulated to facilitate hoop contact. Different modeling alternatives were used to investigate the hoop contact effect on the extreme axial stress and Coulomb friction stress range, which were further validated against measured dynamic axial stress. Good correlation was found by the combination of describing all contact interfaces and constraints due to the grooves in the inner sheath.     

Impulse Controller Design of a Harmonic Drive System with Friction

A friction model was established for impulse control design in a precision control system.First,the physical characteristics of the impulse in momentum,such as motion and energy,were analyzed and formulated.Then,experimental response to a new pulse with two harmonic expansions was studied.The first harmonic is the main pulse to drive the arm,and the second harmonic has two functions:its first half helps the main pulse eliminate the dead zone,and its second half,a negative pulse,stops the arm motion quickly.Finally,an impulse feedback controller was developed.Comparison between simulation and experiments shows the effectiveness of the proposed controller.     

摩擦片式防滑差速器转矩特性对汽车操纵稳定性的影响研究

进行了摩擦片式防滑差速器防滑转矩输出特性测定试验,并分别对装有摩擦片式防滑差速器和普通差速器的汽车,通过试验测定的车厢侧倾角、转弯半径比、前后轴侧偏角差值、横摆角速度及侧向加速度作为对比参数,研究了摩擦片式防滑差速器转矩特性对汽车操纵稳定性的影响。结果表明,摩擦片式防滑差速器能够显著提高汽车的动力性、通过性,改善汽车的操纵稳定性。     

汽车离合器摩擦片数量选择及其参数优化设计

本文从理论计算上阐述了如何就汽车离合器的几种不同功能因素；转矩容量、滑磨功及摩擦片强度等几个方面来选择摩擦片数目的方法，并在此基础上提出了建立数学模型进行优化设计，选取参数的另一种方法。     

发动机活塞组摩擦力实时测量装置及试验研究

系统地阐述了发动机缸套活塞组瞬态摩擦力的测量方法。在对浮动缸套法的原理进行仔细的研究及对其难点进行详细的分析之后，一种改进的具有某些显优点的测量装置被开发出来。并利用这引装置，测出了各种工况下缸套活塞组的摩擦力的变化。