扭力轴多工况二维随机疲劳载荷谱的编制

扭力轴用来减轻自行火炮在行驶过程中地面对车体的冲击。针对扭力轴扭矩载荷谱多工况和非对称的特点，进行单一工况雨流法计数载荷循环、单一工况载荷的分布规律与检验、各工况频次向寿命周期扩展、载荷分级与级循环次数的计算、载荷谱列表。编谱过程基本上包括了多工况非对称型载荷编谱的所有步骤，对编制其它受多工况非对称型载荷的构件的疲劳载荷谱也有参考价值。     

一种逆结构滤波法的轨道车辆轮轨力识别

轮轨动态接触力对车辆运行安全性和稳定性至关重要,考虑到在实际运行条件下,轮轨力很难测量的难题,基于离散时间和动力学状态空间方程,提出了一种逆结构滤波的时域载荷识别方法。该方法以结构响应参数为输入,可实现对非最小相、非并置结构的载荷预测,解决了由于非并置逆系统的不稳定性带来的载荷识别困难。以某轨道车辆为研究对象,以轴箱位置加速度为输入条件,分别建立了10自由度的垂向振动模型和17自由度的横向振动模型,对车辆的轮轨垂向载荷和横向载荷进行了识别。识别结果与具有完全相同动力学参数的SIMPACK仿真模型结果对比,结果表明:反演模型识别出的轮轨垂向力和横向力与SIMPACK仿真结果趋势一致,且均有较强的相关性,识别精度较高;通过滚动振动试验台试验,利用一组测得的垂向加速度响应和垂向位移响应对车辆轴箱的加速度响应进行了识别,并与测得的结果进行对比,相关系数达到0.9756,为极强相关,方法能够用于运行列车轮轨力的监测和安全评估。     

基于聚类分析和支持向量机的非等间隔应力谱编制方法

为保证根据实测应力-时间历程数据编制的应力谱最大程度反映载荷实际作用特性，提出了一种基于疲劳损伤的非等间隔应力谱编制方法。通过引入非等间隔自适应比值系数，根据损伤等效原则，建立应力谱分级数与疲劳损伤关系数学模型；考虑每个应力循环的属性特征，采用聚类分析对所有应力循环进行分类，结合支持向量机多分类进行判别，得到不同分级数下的准确率和预测图；综合考虑数学模型得到的损伤相对误差和支持向量机分类准确率，选取应力谱最佳分级数，编制了相应的非等间隔应力谱，并与目前常用的等间隔和非等间隔8级谱进行比较。分析结果表明：基于损伤等效原则，采用聚类分析和支持向量机进行应力谱分级，不仅考虑了所有应力循环的整体特征，很大程度保留了应力的局部信息和属性，且根据疲劳累积损伤理论得到的损伤与实际损伤结果差异明显降低，从而更能准确反映实测数据的应力特性和疲劳效应，可为其他实测载荷-时间历程数据进行非等间隔分级和载荷谱编制提供参考。     

导弹前定向件公路机动运输疲劳载荷谱的编制及寿命预估

为研究导弹前定向件在公路机动运输环境下疲劳载荷谱的编制方法,选定跑车试验场内标准路面(含鱼鳞路、波形路、卵石路和碎石路及高速路等)进行某型号试验场机动运输试验并实地采集所需信号。根据实测数据的时、频域分析结果,编排试验场机动运输试验流程,组成具有代表性的载荷样本数据,这些数据包含了型号战标要求的不同路面及其占比、不同车速及其占比和刹车、过路障等特殊工况。利用雨流计数法对试验场机动运输试验所得数据进行循环计数,根据参数外推法将循环计数外推至目标里程,进而编制出供设计分析使用的载荷设计谱和试验评估使用的疲劳试验谱。采用试验谱对导弹前定向件进行疲劳加载,验证了产品在寿命期内能够可靠的使用,并且可以延寿三倍以上。该方法可以有效地预估前定向件内部润滑涂层的磨损寿命,为产品的改进设计和同类问题的解决提供了参考。     

非线性渐变刚度钢板弹簧疲劳分析载荷谱编制方法

提出了一种适用于非线性渐变刚度钢板弹簧疲劳可靠性分析评价的载荷谱编制方法。在ANSYS中建立考虑非线性接触的钢板弹簧总成有限元模型并根据台架试验结果进行参数识别,获得了簧片上任意点应力与形变之间的非线性对应关系。在试验场采集获得钢板弹簧在强化路面下的加速度信号,通过处理,获得了板簧弧高随时间变化的信号。结合应力与弧高的对应关系以及弧高随时间变化的信号,精确获得了强化路面下钢板弹簧疲劳热点区域的应力载荷谱。采用雨流计数法对编制获得的载荷谱进行分级计数并依此为基础对疲劳热点进行可靠性分析,预测结果与道路试验相吻合。     

基于循环统计量分析方法的我国干线轨道谱研究

轮轨相互作用产生的振动信号 ,二阶统计特性呈现周期性 ,是循环平稳信号。本文利用循环平稳统计理论 ,分析了二阶统计量循环自相关函数和循环谱密度的特性 ,将其应用于轨道谱特性的研究 ,并与传统方法进行比较 ,显示其在轨道谱数据处理中的优越性。     

基于循环统计量分析方法的我国干线轨道谱研究

轮轨相互作用产生的振动信号，二阶统计特性呈现周期性，是循环平稳信号，本文利用循环平稳统计理论，分析了二阶统计量循环自相关函数和循环谱密度的特性，将其应用于轨道谱特性的研究，并与传统的方法进行比较，显示其在轨道谱数据处理中的优越性。     

车辆-轨道非线性耦合系统交叉迭代算法及应用

运用有限元法建立车辆-轨道非线性耦合系统振动分析模型,该模型包含车辆、轨道两个子系统,其中车辆子系统为附有二系弹簧的整车模型,轨道结构子系统为离散的三层弹性梁模型。两子系统通过轮轨非线性接触力和位移协调条件实现耦合。针对车辆-轨道非线性耦合系统动力学方程提出了交叉迭代算法。为加速迭代收敛速度,引入松弛法对轮轨接触力进行修正。为证明算法的正确性,进行了算例验证。同时还给出了CRH3高速动车在有砟轨道上运行时引起车辆和轨道振动的实例,分析中考虑了轮轨线性和非线性接触及不同列车速度对车辆和轨道结构振动的影响。计算结果表明交叉迭代算法具有程序编制简单、收敛速度快、用时少、精度高的优点;采用轮轨线性接触模型得到的车辆和轨道结构的动力响应比轮轨非线性接触模型得到的结果要大,其中位移、加速度最大值和振幅增大范围约在15 %以内,轮轨接触力最大值和振幅增大范围约在5 %以内。     

基于模态法的高速列车车体关键位置应力谱及寿命评估研究EI北大核心CSCD

基于刚柔耦合理论,建立了考虑车体高频弹性振动的高速列车刚柔耦合动力学模型,利用模态应力恢复法对服役条件下车体关键位置动应力进行了求解。通过扫频激励方法模拟了车辆典型服役模式,识别了典型服役工况下车体动态薄弱位置。进一步研究了车体动态薄弱位置在不同轮轨匹配等效锥度下的特征应力谱。基于京广线线路条件仿真分析了不同轮轨匹配锥度状态下车体关键位置应力谱,并研究了不同应力谱编制方式对车体寿命评估的影响。结果表明:基于扫频激励方法的车体结构动态薄弱位置识别方法,可以有效识别车体结构动态薄弱位置;轮轨匹配等效锥度在镟修周期的动态演变会导致车辆稳定性下降,从而可以显著增大车体关键位置动应力幅值。因此,在车体结构关键位置寿命评估中,考虑轮轨关系动态演变对车辆关键部位应力谱的影响具有至关重要的意义。     

城市用轿车整车结构疲劳载荷谱的采集与处理

对城市用轿车在实际行驶过程中的疲劳载荷进行了实车测试,并进行了统计处理,最后得出了目标载荷谱,为城市用轿车结构疲劳寿命的估算和加速试验提供了科学、可靠的基础数据.针对传统的载荷谱统计处理方法存在的不足,对其进行了改进,其中载荷谱按距离外推采用了非参数统计方法,考虑到汽车的不同使用地域,给出了载荷谱按分位点外推的方法.     

A fatigue reliability analysis method including super long life regime

An affordable and feasible method with moderate accuracy is developed to realize fatigue reliability assessment and life prediction including super long life regime (SLLR) through series of experimental researches on a railway axle steel and real axles. A competition damage mechanism for fatigue crack initiation and growth in SLLR is revealed to fascinate an understanding on wide fatigue damage behavior and to provide a weigh and balance on material primary quality control and on-line inspection capacity. Affordable material probabilistic strength-life (S-N) curves including SLLR are presented by an extrapolation approach on a concurrent probability rule between the S-N relations in mid-long life regime and the fatigue limits with a specified life definition. And then, structural probabilistic S-N curves are deduced by considering scale-induced effect on the material curves. Random cyclic stress-strain (CSS) relations are depicted for constructing structural random stressing history. Reliability assessment and fatigue life prediction are conducted by an interference model of the applied stress deduced from the random CSS relations and the strength capacity derived from the structural probabilistic S-N curves. Availability and feasibility of the present method are indicated by a successful application on a railway axle steel.     

基于车桥耦合随机振动分析的钢桥疲劳可靠度评估

发展了一种基于车桥耦合系统随机振动分析的铁路钢桥疲劳可靠度评估方法,建立车桥耦合系统模型,选取车速和轨道不平顺作为基本随机变量进行随机振动分析,以此确定桥梁构件等效疲劳应力幅及其循环次数的概率模型。在此基础上,建立基于S-N曲线法的疲劳极限状态函数并进行疲劳可靠度分析。以一座铁路下承式钢桁梁桥为例进行了疲劳可靠度评估,并讨论了车速及轨道平顺性对构件疲劳可靠性的影响。结果表明：该文方法可有效用于铁路钢桥疲劳可靠度评估;受车速及轨道不平顺随机性的影响,列车引起的桥梁构件等效疲劳应力幅及其循环次数均具有一定的不确定性,应视为随机变量,二者可采用对数正态分布表示;车速和轨道不平顺可显著影响桥梁构件的疲劳可靠性,疲劳关键构件的可靠度指标随着轨道平顺性增强而提高。     

EURAXLES – A global approach for design,production and maintenance of railway axles: WP1 – Advances in fatigue load analysis and reliability assessment of railway axles

The work presented in this paper was led within the collaborative project “Euraxles” of the FP7 program of the European Commission. It aimed at developing processes and methods that contribute to the minimization of the risk of fatigue failure of railway axles in service. This paper focuses on the development of a method to assess the reliability of axles according to fatigue damage. The proposed approach is mainly based on the stress strength interference analysis (SSIA) and the fatigue‐equivalent‐load (FEL) methods. It aims at calculating the axles’ probability of fatigue failure, by characterizing the variability of real in‐service loads and the scatter of the axles fatigue strength, and at evaluating more accurately the actual design margins. First of all, the main lines of the stress strength interference analysis method are recalled. This method aims at evaluating the in‐service reliability of components for their design or their homologation. It is used in many industries for various applications (mechanical components or systems, electronic elements, etc.). In the second part, the fatigue load analysis method that is proposed for railway axles is described. It starts with a post‐processing of an axle load measurement: from a time signal of forces applied to both wheels fitted on the axle, fatigue cycles of bending moment applied to the axle are identified and transformed into a cyclic equivalent load, the M_eq, which is a measurement of the severity of the initial variable load. Then, virtual but realistic load spectra are generated, thanks to a classification operation followed by a random draw of elementary load data that considers the operation and maintenance conditions of the axle. All the spectra are then analysed thanks to the fatigue‐equivalent‐load method in order to build the distribution of in‐service load severities that gives a picture of the stress to which the axles are submitted. In the third and last part of the paper, the methods are applied to real data of “Société nationale des chemins de fer français” (SNCF), the French national railway operator. Sensitivity analyses are performed in order to quantify the effect on the M_eq of variations of parameters and to verify the convergence and robustness of the process. Finally, results obtained for a passenger coach are given. The comparison between the distribution of load severities and the normative load, defined as according to european standards EN13103, shows that, for the studied axle, the normative load is very conservative. Using the axles fatigue limits identified on full‐scale tests, a stress strength interference analysis is performed to calculate the probability of failure of the axle.     

支持并行设计的产品数据管理系统的研究和开发

提出了支持并行设计的产品数据管理（PDM）系统的基本框架；着重分析了支持并行设计的产品数据管理的关键技术与实现方法，讨论了产品数据定义与管理、集成开发团队的人员组织模式、并行设计过程与工作流管理、设计版本的管理等关键技术，提出了通过构建内部高速局域网络来实现企业并行设计的产品数据管理系统的思想。     

Multi-Resolution Wavelets Analysis Approach for the Recognition of Concurrent Control Chart Patterns

Process control charts have been commonly used as a tool to achieve and maintain acceptable process quality control. The use of Artificial Neural Networks (ANN) for control charts pattern recognition has been studied in recent years. Most of the research has focused on the recognition of single trend, shift, or cyclic patterns, and used simple coding techniques to process the observed data for the neural network. In this article, Multi-Resolution Wavelets Analysis (MRWA) and ANN were used to recognize single and multiple concurrent patterns of control charts. MRWA extracted distinct features for the patterns by providing distinct time-frequency coefficients. A reduced set of parameters was derived from these coefficients and used as input to an ANN classifier. Results have shown that the approach produced adequate recognition of single and concurrent patterns.     

三维实体设计与并行工程

三维实体设计技术为企业实现基于并行工程的产品设计和改型提供了强有力的技术支持。笔者介绍了并行工程的概念,以及基于并行工程的产品设计方法的特点,分析了传统产品设计与并行设计流程的差别。在此基础上,指出了三维实体设计对实现并行、一体化设计和集成化协同工作的支持,并用实例说明了这种方法在汽车覆盖件模具设计开发中的应用。     

土木结构损伤多尺度并发计算方法及其应用

大型土木结构的损伤破坏是跨尺度演化的结果, 因此单一尺度下的结构分析难以正确地反映结构的非线性损伤失效过程。该文根据结构损伤在宏观、细观尺度下的不同特征建立结构一致多尺度模型, 并通过多点约束法进行跨尺度关联, 实现了结构整体线弹性响应分析和局部细节易损部位的细观层次上弹塑性损伤分析的并发进行。计算结果表明:该文提出的结构损伤多尺度并发计算方法能够兼顾结构整体上的线弹性响应和局部易损部位在细观层次上的塑性损伤特征, 在对结构多尺度响应与损伤特征进行准确描述的基础上, 能够获得结构易损局部的细观损伤状态、演化过程及其对结构宏观响应与失效的影响。     

Probabilistic fatigue S–N curves including the super-long life regime of a railway axle steel

A concurrent probability method is proposed for estimating probabilistic fatigue S–N curves including the super-long life regime. This work is based on experimental investigation of LZ50 railway axle steel. Test results reveal that fatigue cracks are initiated from the weakest surface phase and the damage preferentially follows a competition mechanism between the surface quality and subsurface inclusions. The curves are estimated by the test data in the mid-long life regime and the fatigue limits, which were connected together in concurrent probability levels. The accuracy of the curves was verified by the test data in the super-long life regime.     

Concurrent engineering planning on the basis of forward and backward effects of manufacturing processes

An analytical tool has been proposed by the author for developing concurrent engineering within a manufacturing system, on the basis of quantitative analysis of the interconnections existing between the manufacturing processes. This tool takes account of forward and backward effects of the processes and can be employed to set up efficient multidisciplinary teams as the cornerstones of concurrent engineering. In fact, careful analysis of the interconnections existing between various processes is vitally important to set up efficient multidisciplinary teams. A systematic and quantitative approach is much in demand for this purpose, a traceable record of which can barely be found in the literature. The proposed tool also provides a means to evaluate the degree of influence each process exerts over the level of concurrency within the manufacturing system. The forward and backward effects address the effects each process can exercise on its succeeding processes or preceding ones, respectively. Both effects should be taken into consideration to take complete advantages of concurrent engineering. The functional performance of this method has been illustrated through several examples. It was employed in a machine tool manufacturing company, which led to more than a 50% reduction in lead time while the rework was also negligible.