Processing the rig test data of an air filling twin-tube shock absorber

A separation method is proposed to design and improve shock absorber according to the characteristics of each force. The method is validated by rig test. The force data measured during rig test is the resultant force of damping force, rebound force produced by pressed air, and friction force. Different characters of damping force, air rebound force and friction force can be applied to seperate each force from others. A massive produced air filling shock absorber is adopted for the validation. The statistic test is used to get the displacement-force curves. The data are used as the input of separation calculation. Then the tests are carried out again to obtain the force data without air rebound force. The force without air rebound is compared to the data derived from the former tests with the separation method. The result shows that this method can separate the damping force and the air elastic force.

Drag pick cutting tests: A comparison between experimental and theoretical results

This paper aims at reporting the results of a number of drag pick cutting tests on selected igneous rock samples to compare the experimentally determined maximum cutting force （FC） values with theoreti- cally estimated ones. First, a review on theoretical rock cutting models proposed for both chisel and conical picks was presented in detail. Experimental study consists of both chisel and conical pick cutting tests in unrelieved （single-pick） cutting mode with varying cutting depths. FC＇ values were determined from experimental results, and theoretical models were utilized to compute FC for all cutting conditions. Computed and experimentally determined F（ data were then compared for a referenced cutting depth. It is shown that the theoretical models might overestimate or underestimate FC＇ and cannot give reliable results. Finally, explanations for these mismatches were presented.

Real-time multibody modeling and simulation of a scaled bogie test rig

In wheel–rail adhesion studies,most of the test rigs used are simplified designs such as a single wheel or wheelset,but the results may not be accurate.Alternatively,representing the complex system by using a full vehicle model provides accurate results but may incur complexity in design.To trade off accuracy over complexity,a bogie model can be the optimum selection.Furthermore,only a real-time model can replicate its physical counterpart in the time domain.Developing such a model requires broad expertise and appropriate software and hardware.A few published works are available which deal with real-time modeling.However,the influence of the control system has not been included in those works.To address these issues,a real-time scaled bogie test rig including the control system is essential.Therefore,a 1:4 scaled bogie roller rig is developed to study the adhesion between wheel and roller contact.To compare the performances obtained from the scaled bogie test rig and to expand the test applications,a numerical simulation model of that scaled bogie test rig is developed using Gensys multibody software.This model is the complete model of the test rig which delivers more precise results.To exactly represent the physical counterpart system in the time domain,a real-time scaled bogie test rig(RT-SBTR)is developed after four consecutive stages.Then,to simulate the RT-SBTR to solve the internal state equations and functions representing the physical counterpart system in rigs used are simplified designs such as a single wheel or wheelset,but the results may not be accurate.Alternatively,representing the complex system by using a full vehicle model provides accurate results but may incur complexity in design.To trade off accuracy over complexity,a bogie model can be the optimum selection.Furthermore,only a real-time model can replicate its physical counterpart in the time domain.Developing such a model requires broad expertise and appropriate software and hardware.A few published works are available which deal with real-time modeling.However,the influence of the control system has not been included in those works.To address these issues,a real-time scaled bogie test rig including the control system is essential.Therefore,a 1:4 scaled bogie roller rig is developed to study the adhesion between wheel and roller contact.To compare the performances obtained from the scaled bogie test rig and to expand the test applications,a numerical simulation model of that scaled bogie test rig is developed using Gensys multibody software.This model is the complete model of the test rig which delivers more precise results.To exactly represent the physical counterpart system in the time domain,a real-time scaled bogie test rig(RT-SBTR)is developed after four consecutive stages.Then,to simulate the RT-SBTR to solve the internal state equations and functions representing the physical counterpart system in equal or less than actual time,the real-time simulation environment is prepared in two stages.To such end,the computational time improved from 4 times slower than real time to 2 times faster than real time.Finally,the real-time scaled bogie model is also incorporated with the braking control system which slightly reduces the computational performances without affecting real-time capability.

Development of a Test Rig for Axial Strains Measurement in Automobile Wheel

In automobile wheel application, a test rig is vital and used to simulate conditions of the wheel in service in order to affirm the safety and reliability of the wheel. The present work designed a test rig for measuring axial strains in automobile wheel. The wheel used was a five-arm wheel (6JX14H2;ET 42) and Tyre (175 × 65 R 14). Experimental (EXP) test was carried out, with a radial load of 4750 N and inflation pressure of 0.3 MPa, to measure the axil strains which were converted to maximum principal strain values and, compared with data from Finite Element Analysis (FEA) using Creo-Element/Pro 5.0 at wheel’s contact angles of 90 degree (FEA 90 deg), 40 degree (FEA 40 deg) and 30.25 degree (FEA 30.25 deg), respectively. Results show that at the wheel’s point of contact with the ground, maximum principal strain values were highest at the inboard bead seat with a value of about 5.69 × 10-4 mm/mm, followed by the values at the well of about 5.66 × 10-4 mm/mm. The value at the outboard bead seat was least at about 2.22 × 10-4 mm/mm, which was due to the presence of spikes at this location that tends to resist imposed radial loads. However, the highest mean maximum principal strain values at the locations of inboard, well and outboard, were about 2.11 × 10-4 mm/mm, 3.78 × 10-4 mm/mm and .99 × 10-4 mm/mm, respectively. With the highest single value of about 5.69 × 10-4 mm/mm, the inboard bead seat was the most strained location of the wheel. Overall results showed that all values of maximum principal strains were below the threshold value of about 1 × 10-2 mm/mm. The values obtained for EXP and FEA could be said to be in close agreement when compared with the threshold value. With this in mind, the rig is recommended for use in related experimental procedures.

Analysis of wheel-rail adhesion redundancy considering the thirdbody medium on the rail surface

Purpose–In response to the problem of insufficient traction/braking adhesion force caused by the existence of the third-body medium on the rail surface,this study aims to analyze the utilization of wheel-rail adhesion coefficient under different medium conditions and propose relevant measures for reasonable and optimized utilization of adhesion to ensure the traction/braking performance and operation safety of trains.Design/methodology/approach–Based on the PLS-160 wheel-rail adhesion simulation test rig,the study investigates the variation patterns of maximum utilized adhesion characteristics on the rail surface under different conditions of small creepage and large slip.Through statistical analysis of multiple sets of experimental data,the statistical distribution patterns of maximum utilized adhesion on the rail surface are obtained,and a method for analyzing wheel-rail adhesion redundancy based on normal distribution is proposed.The study analyzes the utilization of traction/braking adhesion,as well as adhesion redundancy,for different medium under small creepage and large slip conditions.Based on these findings,relevant measures for the reasonable and optimized utilization of adhesion are derived.Findings–When the third-body medium exists on the rail surface,the train should adopt the low-level service braking to avoid the braking skidding by extending the braking distance.Compared with the current adhesion control strategy of small creepage,adopting appropriate strategies to control the train’s adhesion coefficient near the second peak point of the adhesion coefficient-slip ratio curve in large slip can effectively improve the traction/braking adhesion redundancy and the upper limit of adhesion utilization,thereby ensuring the traction/braking performance and operation safety of the train.Originality/value–Most existing studies focus on the wheel-rail adhesion coefficient values and variation patterns under different medium conditions,without considering whether the rail surface with different medium can provide sufficient traction/braking utilized adhesion coefficient for the train.Therefore,there is a risk of traction overspeeding/braking skidding.This study analyzes whether the rail surface with different medium can provide sufficient traction/braking utilized adhesion coefficient for the train and whether there is redundancy.Based on these findings,relevant measures for the reasonable and optimized utilization of adhesion are derived to further ensure operation safety of the train.

低压等离子喷涂NiCoCrAIYTa涂层的抗燃气热冲击性能研究

为了保障涡轮叶片材料的抗高温氧化与耐热腐蚀性能,采用低压等离子喷涂技术在航空发动机涡轮叶片试验件上成功制备了NiCoCrAlYTa涂层。通过对不同粉末制备的NiCoCrAlYTa涂层进行1000℃/75 h燃气热冲击试验,研究了带涂层叶片尺寸、涂层表面形貌、相组成和显微组织、涂层厚度和均匀性等性能参数的变化。结果表明:热冲击试验后,不同涂层叶片的整体尺寸未发生显著变化,表明涂层在高温环境下具有稳定的尺寸;涂层表面形成了Al_(2)O_(3)膜和NiAl_(2)O_(4)尖晶石,保留了较好的结构完整度,这有助于提高涂层的耐腐蚀性能;涂层的物相组成主要包括γ-Ni、γ’-Ni_(3)Al和少量的β-NiAl,形成了贫Al区、互扩散区、二次反应区等典型微区结构,析出的TCP相为R相,表明在热冲击过程中涂层发生了相变;不同粉末制备的NiCoCrAlYTa涂层均表现出了良好的抗热冲击性能,为航空发动机涡轮叶片的高温应用提供了可行的涂层方案。

悬架K&C试验台在底盘开发中的技术应用

简要介绍了国内悬架K&C试验台的应用及发展情况,详细探讨了悬架K&C试验台及其在底盘开发调校中的应用,阐述了悬架K&C特性研究的作用及其必要性,以及所研究的主要内容。

基于K&C试验台的扭力梁与多连杆悬架研究

以某新旧两款商务车为研究对象,该两款车型后悬架分别采用扭力梁式悬架与多连杆式独立悬架,利用K&C试验台获取其悬架系统的特性参数,对比分析平行轮跳试验结果中的车轮外倾角以及车轮前束角的差异和特点,然后基于整车基本数据使用汽车仿真软件Carsim分别建立整车模型,进行转向盘转角阶跃输入仿真,并通过整车侧向加速度与横摆角速度的变化来分析两种不同的后悬架对这款车型整车操纵稳定性的影响。结果表明,相对于扭力梁式后悬架,多连杆式后独立悬架能够加快稳态响应,减小谐振幅度,而且在特殊工况下,侧倾现象明显更小,响应速度更快。

K&C试验台及其应用

K&C试验台是一种测量底盘K&C特性参数的设备,介绍了K&C试验台的定义、分类和基本结构,重点阐述其工作原理及试验项目,对其在汽车开发中的应用进行了说明,最后介绍了试验台的设计及应用发展状况,并提出了对试验台的应用建议。

A Robust Fuzzy Tracking Control Scheme for Robotic Manipulators with Experimental Verification

The performance of any fuzzy logic controller (FLC) is greatly dependent on its inference rules. In most cases, the closed-loop control performance and stability are enhanced if more rules are added to the rule base of the FLC. However, a large set of rules requires more on-line computational time and more parameters need to be adjusted. In this paper, a robust PD-type FLC is driven for a class of MIMO second order nonlin- ear systems with application to robotic manipulators. The rule base consists of only four rules per each de- gree of freedom (DOF). The approach implements fuzzy partition to the state variables based on Lyapunov synthesis. The resulting control law is stable and able to exploit the dynamic variables of the system in a lin- guistic manner. The presented methodology enables the designer to systematically derive the rule base of the control. Furthermore, the controller is decoupled and the procedure is simplified leading to a computationally efficient FLC. The methodology is model free approach and does not require any information about the sys- tem nonlinearities, uncertainties, time varying parameters, etc. Here, we present experimental results for the following controllers: the conventional PD controller, computed torque controller (CTC), sliding mode con- troller (SMC) and the proposed FLC. The four controllers are tested and compared with respect to ease of design, implementation, and performance of the closed-loop system. Results show that the proposed FLC has outperformed the other controllers.

汽车钢板弹簧CAE仿真分析与台架试验对标研究

针对新设计汽车钢板弹簧,有物理试验和计算机辅助工程(Computer Aided Engneering,CAE)仿真两种手段来评估板簧的疲劳寿命,物理试验周期长、费用高,CAE仿真周期短、费用低。目的是找出一种应用CAE仿真分析手段来有效分析预测钢板弹簧疲劳寿命的方法,从而实现缩短板簧开发周期并降低开发成本;对钢板CAE仿真和台架试验进行了刚度及强度的对标分析,找出了能够准确模拟刚度和强度的CAE刚强度仿真方法;在确保CAE仿真模型能准确分析板簧刚强度的基础上,通过实测板簧材料疲劳性能曲线,基于Miner累积损伤理论,应用不同表面修正系数对钢板弹簧进行寿命分析,并和疲劳台架试验对标进行分析,找出了一种能够较为准确评估板簧寿命的CAE疲劳仿真分析方法。最终形成了一套基于CAE分析的较为可靠的钢板弹簧疲劳寿命预测方法,该方法有效性较好,对有效预测汽车钢板弹簧的疲劳寿命具有较高的工程价值。

An experimental study on the effects of friction modifiers on wheel-rail dynamic interactions with various angles of attack

By modifying friction to the desired level,the application of friction modifiers(FMs)has been considered as a promising emerging tool in the railway engineering for increasing braking/traction force in poor adhesion conditions and mitigating wheel/rail interface deterioration,energy consumption,vibration and noise.Understanding the effectiveness of FMs in wheel–rail dynamic interactions is crucial to their proper applications in practice,which has,however,not been well explained.This study experimentally investigates the effects of two types of top-of-rail FM,i.e.FM-A and FM-B,and their application dosages on wheel–rail dynamic interactions with a range of angles of attack(AoAs)using an innovative well-controlled V-track test rig.The tested FMs have been used to provide intermediate friction for wear and noise reduction.The effectiveness of the FMs is assessed in terms of the wheel–rail adhesion characteristics and friction rolling induced axle box acceleration(ABA).This study provides the following new insights into the study of FM:the applications of the tested FMs can both reduce the wheel–rail adhesion level and change the negative friction characteristic to positive;stick–slip can be generated in the V-Track and eliminated by FM-A but intensified by FM-B,depending on the dosage of the FMs applied;the negative friction characteristic is not a must for stick–slip;the increase in ABA with AoA is insignificant until stick–slip occurs and the ABA can thus be influenced by the applications of FM.

Experimental prototyping of the adhesion braking control system design concept for a mechatronic bogie

The dynamic parameters of a roller rig vary as the adhesion level changes.The change in dynamics parameters needs to be analysed to estimate the adhesion level.One of these parameters is noise emanating from wheel–rail interaction.Most previous wheel–rail noise analysis has been conducted to mitigate those noises.However,in this paper,the noise is analysed to estimate the adhesion condition at the wheel–rail contact interface in combination with the other methodologies applied for this purpose.The adhesion level changes with changes in operational and environmental factors.To accurately estimate the adhesion level,the influence of those factors is included in this study.The testing and verification of the methodology required an accurate test prototype of the roller rig.In general,such testing and verification involve complex experimental works required by the intricate nature of the adhesion process and the integration of the different subsystems(i.e.controller,traction,braking).To this end,a new reduced-scale roller rig is developed to study the adhesion between wheel and rail roller contact.The various stages involved in the development of such a complex mechatronics system are described in this paper.Furthermore,the proposed brake control system was validated using the test rig under various adhesion conditions.The results indicate that the proposed brake controller has achieved a shorter stopping distance as compared to the conventional brake controller,and the brake control algorithm was able to maintain the operational condition even at the abrupt changes in adhesion condition.

基于整车路面谱的副车架开裂台架试验及仿真

针对前悬架稳定杆与副车架连接处在整车试验场耐久测试过程中出现的疲劳破坏问题,通过对稳定杆进行贴片标定,获得了试验场环境下稳定杆的连杆力和稳定杆扭转相对位移的强化耐久路谱,设计搭建了稳定杆副车架系统的物理台架,并按照耐久性规范进行了台架试验。试验结果表明:该台架试验装置能良好地再现整车耐久路试下的断裂位置,疲劳寿命相对于整车耐久路试的疲劳寿命偏差仅为2.5%。在此基础上,建立了稳定杆与副车架多体的仿真模型,设定了与系统试验台架相同的约束边界,通过虚拟迭代的方法及准静态有限元疲劳寿命分析法对系统进行了仿真分析。仿真得到稳定杆连杆力和稳定杆扭转相对位移信号,与测试结果进行对比分析可以看出,时域下相位和幅值重合度良好,频域下的PSD谱重合度较高,穿级计数载荷统计基本一致,载荷相对损伤均在1附近,相关风险位置处的仿真疲劳寿命与整车耐久试验寿命偏差比为6.25%,获得了较高精度的风险位置载荷,实现了耐久风险位置的复现。最后,基于仿真模型对副车架风险位置处进行了结构优化设计,改进后的方案顺利通过了后续的台架试验和整车耐久路试。

试验台约束对滑动轴承动特性识别精度的影响

在滑动轴承的动特性测试中,试验台参数对动特性测试精度有重要的影响。以某倒置式轴承动特性试验台为研究对象,基于轴承动力学正反问题,提出滑动轴承动特性系数识别精度的仿真评估方法,分析不同激振频率时试验台约束参数对轴承动特性系数识别精度的影响规律,并对激振频率和约束参数的取值范围进行优选。结果表明:在较低激振频率的条件下,当约束刚度和约束阻尼取值较小时,动特性系数的识别精度受测试误差的影响不大,随着约束刚度和约束阻尼取值增大到一定值,动特性系数的识别精度受测试误差的影响迅速增大。针对研究的试验台,选择激振频率在30~300 Hz之间,选择试验台约束刚度小于试验轴承刚度的0.3%,试验台约束阻尼小于试验轴承阻尼的7%时,能够保证较好的轴承动特性系数的测试精度。

自动变速器CAN总线通信技术的实现

介绍一种自动变速器CAN总线接口技术的实现。在研究自动变速器半实物仿真试验台的基础上,设计了以Motorola公司16位微处理器MC9S12DP256 B为核心的CAN总线硬件接口电路,采用标准CAN总线的通讯协议,编制了CAN总线结点软件。在试验台上成功实现了CAN结点之间的数据相互通讯,为车载CAN总线开发设计奠定了基础。

油气井下CO_2动态腐蚀模拟试验装置的研制

CO2腐蚀在石油行业中普遍而严重,室内模拟试验难度大,现有的动态腐蚀试验装置无法真实模拟井下流体的流动状态。研制了一种模拟性和实用性都较强的井下CO2动态腐蚀模拟试验装置。该试验装置不仅能够真实模拟井下油套环空及抽油泵吸入口附近腐蚀介质的流速和流态,还能评价井下动液面以上、动液面附近、动液面以下、泵吸入口附近、筛管以下等不同位置油套受温度、CO2分压、流速等因素控制下的腐蚀状态。结果表明:在现场工况条件下,试样腐蚀速率随温度、CO2分压、流速的增大而增大,与Corrtest Co.35 MPa耐腐蚀高压釜试验结果一致,并且较后者更接近于现场挂片试验结果;横向比较井下不同位置的腐蚀状况发现,泵吸入口附近套管的腐蚀速率最大,并且以局部腐蚀为主,腐蚀形貌与现场套管腐蚀穿孔特征相吻合。该装置结构合理,性能稳定,为研究井下CO2腐蚀机理及影响因素提供了新的测试手段和研究方法,具有很好的应用前景。