基于单片机的柔性封闭线材长度测量的系统设计

汽车行业中,钢丝圈的作用是赋予胎圈必要的强度和刚性,使轮胎牢牢固着于轮辋上,其质量直接影响轮胎的使用寿命及汽车的安全。本文主要介绍了基于单片机的钢丝圈内周长测长仪的机械结构、测量原理及电控单元的硬件和软件系统,其测量精度可达到±0.1mm,且稳定可靠。     

The effect of rubber contact on the fretting fatigue strength of railway wheel tire

The cause of the ICE train derailment, which occurred in 1998 at Eschede, was fatigue failure originating on the inside of the wheel tire. Rubber-sprung resilient wheels were used for the trailer cars. The wheel tire is mounted on the wheel disc. Thirty-four rubber pads were arranged between the wheel disc and the wheel tire. It was postulated that fretting fatigue between the rubber block and the inner side of the tire might have an influence on the initiation of the incipient crack. In order to clarify the influence of the rubber contact on the fatigue strength of the tire, fretting fatigue experiments under rubber contact conditions were performed. During the fundamental fretting fatigue test using bridge pads and small size carbon steel specimens, no typical fretting damage such as fretting wear and minute cracks were observed due to contact of the rubber. Stress conditions of the rubber-sprung wheel under vertical and lateral wheel loads were evaluated by a three-dimensional elastic stress analysis. Since the rubber is a super-elastic material, the Mooney-Rivlin model was used in the FEM calculation. It was found that the wheel tire is subjected to a cyclic stress during one revolution of the wheel and the maximum stress occurred at the center of the inner surface of the tire where the fatigue crack initiated. Fatigue strength of the wheel tire was determined by the rotating bending fatigue testing of specimens taken from the tire. It was found that the tire with an 862 mm diameter at a wheel load of 80 kN had a safety factor more than 3.5 from a fatigue limit diagram with a failure probability of 0.01. To confirm the fretting damage under the rubber contact and the result of the fatigue strength evaluation, fatigue tests of a full size wheel were made. After 20 million cycles at the wheel load of 280 kN, which was just below the endurance limit estimated by the endurance limit diagram, no fretting damage and no fatigue cracks were observed. The wheel was, however, fractured at 1.56 million cycles under the maximum load of 308 kN, which was just above the endurance limit. The estimation of the safety factor of 3.5 estimated from the endurance diagram was confirmed by the full size fatigue testing. It was concluded that there was no effect of fretting due to the rubber contact on the fatigue strength of the rubber-sprung single-ring railway wheel.     

新型汽车轮胎防爆内胎的研制

针对目前防爆轮胎存在防爆效果不佳、价格昂贵、适用范围小等问题,研制了由弹性环套、压力开关、充气装置、安全锁组成的新型防爆内胎,具有结构简单、成本低、安装便捷、起效迅速等特点。选择某型轿车轮胎作为改造和实验对象,进行了动平衡试验和轮胎抗刺扎试验、轮胎脱圈试验等多项道路试验。试验结果表明,新型防爆内胎轮胎动平衡测试结果良好,在汽车高速行驶中爆胎失压后起效迅速,能有效防止车辆侧滑、跑偏,保障汽车安全行驶或停车,具有较好的应用前景。     

Multi-cavity Tire

This new utility model relates to a vehicle tire, especially to the multi-cavity tire which the inside of tire is divided into many cavities. The feature of this new utility model is that, several interlayers are provided in the direction of the tire＇s circumferential cross section, which divides the tire into many cavibies. The center of the tire cavity is provided with the ring-like rubber pipe, which passed through each interlayer of the cavity. There is an air hole on the rubber pipe. If this tire is punctured during the vehicle runing, the air is leaked from the fracted cavity, but the air in other cavities would flow out through the hole on the rubber pipe, so the flpw is very slow, therefore it can play the cushion role, and it also can reduce the burst power, because the air in each small cavity is little.     

滑移线连续和平稳分布的变径车轮设计

基于轮地接触动力学理论,设计出一种适应沙壤土环境、具有内外双层紧贴刚性轮片和中部轮刺的新型变径车轮.分析了变径轮不同断面与土壤的作用机理和土壤流动滑移模型,通过对滑移线公式详细推导和数值计算,获得其滑移半径和等效轮周的变化规律,提出了以断面高度为主、倾角为辅的设计思想.建立了满足平稳和连续滑移线模型的剪切滑移交错层断面...     

铝合金车轮13°冲击试验仿真分析

为了减少铝合金车轮性能检测的试验次数以提高车轮的设计研发效率,建立铝合金车轮13°冲击试验的数值模型进行仿真试验非常必要。在充分考虑冲击试验台静态与动态效果的基础上,建立包括冲头、车轮总成和试验台架的铝合金车轮冲击试验有限元模型,其中试验台架上的橡胶支座采用弹簧—阻尼单元进行模拟,且将轮胎安装所产生的车轮预应力作为初始条件,使用非线性有限元动力分析软件LS-DYNA对铝合金车轮冲击过程进行仿真分析。通过对车轮上若干测量点应变值的有限元仿真结果与试验结果的比较,确认与铝合金车轮实际台架试验相等效的计算机模拟试验平台的有效性。该计算机模拟试验平台的建立对铝合金车轮的前期设计开发具有重要的指导意义及应用价值。     

基于新型机械弹性车轮的整车平顺性分析

针对越野汽车的特殊行驶环境,为了提高轮胎的防刺破、防爆胎和安全性能,提出一种新型机械弹性安全车轮。在深入分析其结构的基础上,建立了有限元模型,并求解了各个方向的刚度。在ADAMS中建立了包括新型机械弹性车轮在内的整车模型,经随机路面输入仿真分析得出如下结论：基于机械弹性车轮的整车符合平顺性要求且满足普通轮胎的平顺性规律。在高速下,基于子午线轮胎整车的平顺性略优于基于新型机械弹性车轮整车的平顺性。     

扭曲管管内传热及流动特性数值模拟

扭曲管是应用于制冷行业中新型管壳式换热器的高效换热管,强化了管内传热,壳程不设折流板以降低壳程流阻。本文通过数值模拟研究了扭曲管管内传热及流动特性。通过建立不同规格的扭曲管物理模型,得出扭曲管的扭曲程度S/de越小、截面压扁程度Ai/Bi越大,扭曲管的强化传热性能就越好,但是同时流阻也会增大;反之则相反。     

轮胎稳态侧倾力学特性理论建模

研究了轮胎侧倾建模机理,并在此基础上导出了轮稳仿而倾的侧向力、回正力矩、纵向阻力和翻转力矩特性表达式。讨论了车轮定位时侧倾角与前束角的关系,引入了有效侧倾角概念,并基于此给出了子午线轮胎比斜交轮胎侧倾侧向力小的理解解释。     

New Method for Monitoring Tire Pressure of Cars Based on the Tire Radial Deformation

Monitoring tire pressure of cars and signaling abnormal conditions is an important means to prevent deadly accidents. Large achievements have been gained, especially in direct tire pressure monitoring system(TPMS). But there has been rarely research on indirect TPMS in the world. In China, the research on indirect TPMS is almost lacking. The international research on the indirect monitoring tire pressure method is mainly based on measuring and comparing the rotating speed of wheels. But it is very difficult to measure wheel rotating speed accurately because of the influence of many random factors. In this paper, the authors propose a new method in which the tire pressure can be monitored indirectly. This method can be used for tire calibration, wheel speed frequency standardization, wheel speed frequency comparison, and abnormal tire pressure determination. The pulse frequencies from wheel speed sensors of ABS are used to indicate tire deformation. Because the frequency has a relationship with tire deformation, the tire deformation reflects the tire pressure. Small sample statistics is used in the new method to increase the accuracy, and the experimental samples using the principle of the new method have been made and tested. The result of vehicle tests on road demonstrates that the method is efficient and accurate to monitor tire pressure. The research has positive potential for developing products.     

Analysis of railway wheel rolling process based on three-dimensional simulation

Rolling is one of the key stages of railway wheel hot forming process. In this work, a three-dimensional finite element analysis on wheel vertical rolling process based on some strategies proposed has been carried out by using FE code SuperForm. In modeling, a virtual mandrel is exploited in the hub hole to keep the wheel central instead of the guide rolls and centering rolls. Some features of the wheel forming are deeply investigated such as the rim diameter expanding, the rim lateral spreading, the metal flow in the circumferential direction, and the stresses distribution. The results show that (1) the rim radius expanding mainly occurs in the two affected zones before and after the back roll deformation zone; (2) the rim metal has flow trend in the circumferential direction during rolling, the metal of the intersection area, between the tread and the rim external side surface has the largest relative angular displacement; and (3) the tensile stresses of the web both in radial and circumferential directions during rolling result in the web thickness decreasing by about 3 mm for the investigated wheel. The simulations results reveal the forming mechanisms of wheel rolling, laying the basis for designing and optimizing railway wheel forming process.     

轮毂轴承耐久性试验方法若干问题的研究

针对轮毂轴承耐久性试验方法中的若干问题进行了研究,通过对轮毂轴承中心线和轮胎受力中心线的偏移量的研究,得出轮毂轴承模拟试验载荷加载位置的确定方法;针对轮毂轴承内圈或外圈旋转对轮毂轴承寿命影响的研究,得到轮毂轴承旋转方式在试验台上的实现方法;还对轮毂轴承失效的监控方法进行了讨论,提出耐久性试验中利用峭度值来判断轮毂轴承是否失效是有效实用的方法。     

高锰钢前导轮铸造工艺模拟及优化

高锰钢前导轮内腔结构复杂,需要合理的铸造工艺以避免填内部产生铸造缺陷。为此,采用商业软件ProCAST对导轮轴孔处设一个明冒口的单冒口工艺（SR）和两个明冒口的双冒口艺艺（DR）进行缺陷预测、计算发现,单冒口工艺（SR）的缺陷形成倾向低于双冒口的工艺（DR）。进而,通过调整单冒口工艺（SR）的冷铁形状、位置及增大轮缘处暗冒口体积．提出优化工艺M1;在M1基础上,通过减小轴孔处明冒口体积,并加大该处冒口保温砖厚度,提出优化工艺M2,模拟计算表明,采用M1和M2工艺均可消除导轮轮缘处的缩孔缩松缺陷;以M2的热裂倾向最小,热裂纹主要出现在前导轮内腔垂直拐角处和轴孔附近。     

铝合金车轮侧向刚度影响因素分析

使用CATIA开展铝合金车轮参数化设计,通过调整轮心结构、轮辐结构、轮辋结构、轮缘结构、窗口结构得到不同的铝合金车轮三维数据;使用Hypermesh划分网格、Nastran求解,得到不同结构铝合金车轮的侧向刚度;分析车轮侧向刚度随车轮结构参数变化的敏感程度,结果显示轮心厚度、轮心直径、轮心根部圆角、轮辐内侧厚度、轮心减...     

轮力传感器及其在汽车道路试验中的应用

汽车轮力传感器串接在轮胎轮辋和车桥轮毂之间，用于在汽车实车道路试验和室内台架试验时测量由地面或激振器作用于轮胎的六分力。轮力传感器研制的关键技术包括可靠且准确的信号和能量传输、信号的解耦、强度和结构安装要求等。详细介绍了轮力传感器的研究进展、设计原理、性能评价和误差分析等，最后对其在汽车道路试验中的具体应用做了介绍。     

An experimental study on dryout pattern of two-phase flow in helically coiled tubes

Experimental results are presented for the effects of coil diameter, system pressure and mass flux on dryout pattern of two-phase flow in helically coiled tubes. Two tubes with coil diameters of 215 and 485 mm are used in the present study. Inlet system pressures range from 0.3 to 0.7 MPa, mass flux from 300 to 500 kg/m2s, and heat flux from 36 to 80 kW/m2. A partial dryout region exists because of the geometrical characteristics of the helically coiled tube. The length of the partial dryout region increases with coil diameter and system pressure. On the other hand, it decreases with increasing mass flux. The critical quality at the tube top side increases with mass flux, but decreases with increasing system pressure. This tendency is more notable when the coil diameter is larger. When the centrifugal force effect becomes stronger, dryout starts at the top and bottom sides of the tube. However, when the gravity effect becomes stronger, dryout is delayed at the tube bottom side. In some cases when the mass flux is low, dryout occurs earlier at the outer side than at the inner side of the tube because of film inversion.     

Modified Building Structure for Tire Bead

This new utility model is related to a modified tire bead building structure which mainly consists of a major body and a few pieces of components to form the tire bead. The outside of the main body is an combined open space. The two side walls and the bottom of the combined space forms a straight angle or an obtuse angle, so it facilitates for mold stripping after the main body is formed. The assembly is curving and a complete circle can be formed by several assemblies. The outside of the assembly is corresponding to the combined space and its inner side is formed a channel. A few curving assemblies could be applied to the combined space of the main body to form acomplete tire bead body. After assembly, the bead could be put into the tire body from this channel.     

基于主动转向的爆胎汽车操纵稳定性模糊控制研究

汽车在高速行驶时发生爆胎后引起的交通事故危害较大,为了能够更好地控制爆胎后的方向稳定性,主要是通过分析爆胎后的主要影响因素,建立爆胎汽车方向失稳动力学模型,并建立基于主动转向的模糊控制器。重点研究了汽车爆胎后车轮的滚动半径变小以后对汽车行驶方向失稳的影响,进而分析由于爆胎汽车姿态变化而引起的载荷转移,以及由于载荷转移所导致的各个车轮上的侧偏力大小对汽车行驶方向失稳的影响。最后通过仿真验证模糊控制系统能够较好的纠正由于爆胎引起的汽车跑偏。     

Reliability analysis of stainless steel/carbon steel double-layered tube on the basis of thermal deformation behavior

The thermal expansion of pipes depends on both the temperature of the pipe and the expansion coefficient of the piping material at the operating temperature. In the case of a double-layered tube consisting of two different tube materials, the thermal deformation behaviors are dependent on the relative tube sizes, thermal expansion coefficients, and the mechanical properties of the inner and outer tubes. For the safe and reliable application of double-layered tubes that are fabricated by hydroforming, the thermal stress in circumferential direction and the gap between the inner and outer tubes need to be analyzed over a wide range of temperatures (?50°C～200°C). As it is difficult to measure the thermal stress and the gap between tubes at operating temperature, this study has analytically investigated the thermal deformation behavior of a double-layered tube. From the analytical model, the effect of hydraulic pressure, residual stress, and the relative sizes of the inner and outer tubes on the resultant thermal deformation, such as the circumferential thermal stress and the gap between inner and outer tubes, has been analyzed. The analytical results provide a theoretical basis for determining the reliable operating temperature of double-layered tubes.     

Fabrication of small size inner spiral ribbed copper tube by fluid mandrel drawing

This paper is concerned with the development of ultra-small inner spiral ribbed copper tubes with high-quality heat transfer. Since the demand for the ultra-small tubes in electrical appliances is currently high and will be greater in the future, the technology employed must enable the production of inner spiral ribbed fine tubes with various features, such as small size, high quality, high functionality, and low processing cost so as to meet the increasing demand. The conventional production method is suitable for large tubes with high drawability but is unsuitable for fabrication of long ultra-small tubes because of the difficulty to manufacture both an ultra-small spiral ribbed mandrel and a floating plug. This research paper has proposed four drawing methods as follows: tube sinking, water, oil, and wax as mandrels and presented the comparison of seven parameters, i.e., drawing stress ratio, wall thickness ratio, ribbed base width ratio, ribbed tip width ratio, ribbed height ratio, ribbed pitch ratio, and ribbed spiral angle ratio. It was found that tube sinking was unfit for making the ultra-small inner spiral ribbed copper tubes due to the resulting high ratio of wall thickness. The results of all the parameters were similar in the cases of oil and wax. Despite less impressive outcomes, water was easily removed from the inner spiral ribbed copper tube compared to oil and wax. Thus, the tube drawing using water as mandrel was most suitable for the production of the inner spiral ribbed copper tube.