CRH3型动车组车轮的疲劳寿命分析

为了真实计算动车组车轮疲劳寿命,在分析国内外车轮相关标准的基础上,提出了利用车轮静强度分析和有限元名义应力方法的高速动车组车轮强度的分析方法.基于UIC510-5标准,确定了车轮强度分析的计算载荷工况,利用有限元静强度分析方法对CRH3型动车组车轮进行疲劳强度评价,结果表明机械载荷工况下车轮强度满足要求;最后基于线性损伤累积法则,利用有限元名义应力方法和ANSYS/WORKBENCH得出车轮的疲劳寿命预测图及安全系数图,计算结果满足疲劳寿命要求,为动车组的安全性维护提供了理论依据,对动车组的安全运行有极强的实际应用价值.     

动车组头车车体疲劳强度分析

以某350km/h动车组头车车体为研究对象,在ANSYS中建立车体有限元模型,依据EN12663标准对其进行刚度和静强度分析,得到车体垂向最大变形为539mm,最大当量应力为2802MPa,最大当量应力出现在空气弹簧约束处,小于材料的屈服极限,满足车体刚度和静强度要求;根据动车组实际线路运行情况,增加明线会车、隧道会车、隧道通过和侧风工况4种气动载荷工况进行静强度分析,4种工况车体的静强度均小于车体材料的屈服极限;采用Goodman疲劳曲线图对车体疲劳强度进行评估,各部位安全系数均大于1,满足疲劳强度的要求。     

气动载荷下动车组车体疲劳寿命评估

使用Solid Works软件建立CRH2型动车组头车车体的三维模型,然后利用ANSYS与多种CAD和CAE软件的无缝接口技术,将车体三维模型成功导入ANSYS WORKBENCH有限元仿真分析软件,并完成有限元网格的划分。在此基础上,先进行车体在气动载荷下的静力学分析,然后加载获取的的随机载荷谱,对车体进行疲劳分析,得到了车体的寿命、安全系数及损伤等相关参数。结果表明,车体的疲劳寿命满足设计要求,最小安全系数为1.022 4。     

应用多体有限元法预测车体结构疲劳寿命

利用多体动力学和有限元法结合的混合方法对机车车体结构疲劳寿命进行仿真研究.首先在SIMPACK中建立机车整车的多体系统动力学模型,根据不同的载荷工况计算其载荷时间历程;其次根据有限元准静态应力分析法,获得车体结构的准静态应力应变影响因子(stresses influence coefficient,SIC),再利用模态分析技术获得车体结构固有频率和模态振型,以及确定车体结构危险点位置.基于危险应力分布的动载荷历程,结合车体材料的S-N曲线以及Palmgren-Miner损伤理论,利用FE-FATIGUE软件的安全强度因子分析法和WAFO(wave analysis for fatigue and oceanography)技术进行标准时域的车体结构疲劳寿命预测,其中包括应力应变的循环计数、损伤累积和寿命预测.实测结果和仿真结果相互对比表明,这种方法可以有效预测车体结构的疲劳寿命,其精度和动力学与有限元模型的精度有关.     

动车组车体防火强度及刚度计算分析

提高铝合金车体的防火能力,对于提高动车组安全性,避免伤亡事故的发生有重要的意义。利用ANSYS软件以有限元分析法为基础对某动车组在发生火灾时车体强度、刚度进行了仿真分析,计算结果表明:铝合金车体转向架区域变形相对较小,不会影响转向架的自由旋转,能够满足标准要求。     

某铁路平板车车体强度的多标准联合仿真分析

车体强度对于车体的使用寿命及安全可靠性具有重要意义,国内外对焊接结构的疲劳分析理论与方法也较为完善,但是在同种载荷工况作用下,依据不同的标准技术方法及理论所得的疲劳强度分析也会有所偏差,准确分析车体的疲劳强度显得尤为重要。首先,采用UG、HyperMesh、ANSYS Workbench及HyperView软件的联合仿真平台,构建平板车车体的有限元模型;其次,参照EN 12663-1:2010标准技术要求,依据平板车的静载荷工况完成静强度分析;最后,为准确分析车体的疲劳强度,分别依据BS 7608:1993标准技术方法、AAR标准疲劳分析方法对其进行疲劳强度分析,研究对比不同标准技术方法下的累积损伤值大小,评估标准技术方法的最优选择。计算结果表明:车体的静强度与疲劳强度均满足设计要求,车体静强度下的最小安全系数为1.152;BS 7608:1993标准技术方法下车体疲劳强度的疲劳累积损伤最大值为0.165 7,AAR标准疲劳分析方法下的车体疲劳累积损伤最大值为0.064 9,将两者的疲劳累积损伤值对比后发现,BS 7608:1993标准技术方法下的疲劳累积损伤值较大,结合理论评估方法对比,综合分析表明,采用BS 7608:1993标准技术方法下的疲劳分析相对更全面,结果也相对更保守。     

高速动车组整车车体疲劳试验方法研究

车体是高速列车的重要承载部件,疲劳试验可以准确评估车体的疲劳寿命,还可以验证仿真计算模型的准确性,并可以将仿真分析时考虑不全面的工艺因素考虑在内。通过比较国内外相关标准确定了包含车体垂向、中心销横向、纵向以及车钩纵向载荷在内的高速动车组整车车体疲劳试验载荷,根据试验载荷制定了整车车体的疲劳试验方案,并根据该方案完成了国内首次高速动车组整车车体的疲劳试验。通过疲劳试验发现车钩座内侧筋板焊缝存在疲劳安全隐患并提出了优化方案,对优化后的方案近一步进行验证,最终证明了该型高速动车组车体的疲劳寿命满足设计要求。     

驮背运输车鞍座的冲击强度和疲劳强度分析

利用ANSYS有限元分析软件,参考AAR M-952针对评估集装箱锁座的冲击强度规定,分析铁路驮背车鞍座在半挂车各向冲击加速度载荷作用下的受力状态,评定其冲击强度;参考EN12663规定的车体垂向和横向疲劳载荷,对该鞍座进行疲劳强度评定。分析结果表明,鞍座的冲击强度和疲劳强度能够满足驮背运输的要求。     

单元大小对货车车体强度及疲劳有限元分析结果影响研究

对C70敞车车体进行三维几何建模,然后分别使用边长为20 mm和30 mm的壳单元对其进行有限元划分,最后基于铁路相关规范分析计算不同单元大小的敞车车体强度,根据IIW标准对敞车车体进行疲劳寿命评估。计算结果显示,在同种工况下,单元大小的改变对车体强度的计算结果影响较小,对疲劳寿命的计算结果影响较大,即车体强度的计算结果对单元大小不敏感,疲劳寿命的计算结果对单元大小敏感。在使用IIW标准计算疲劳寿命时,为了避免单元大小敏感特性,需要在焊缝处进行单元节点细化,保证疲劳寿命计算结果的稳定性。     

基于残余应力修正疲劳强度原理的桥壳疲劳寿命分析

以装载机板焊驱动桥壳为研究对象,首先建立桥壳的有限元分析模型,然后运用有限元分析软件ANSYS对其进行强度分析,建立残余应力-疲劳强度修正数学模型,并将运用X射线残余应力测试技术测量所得的桥壳残余应力通过修正数学模型进行强度分析的结果修正,最后将强度修正结果导入根据基于残余应力修正的应力-寿命数学模型编制的名义应力法和局部应力应变法疲劳寿命计算软件中,对桥壳的疲劳寿命进行求解,所得结果与桥壳疲劳寿命台架试验数据较为接近,表明通过基于残余应力修正疲劳强度原理的装载机板焊桥壳疲劳寿命分析方法增加了分析数据的可靠性。     

三绕组变压器的双绕组等效建模及在Matpower中的应用

针对实际电网存在着大量的三绕组变压器,但国际上一些著名商业软件,如BPA仿真软件、Matpower这一权威潮流计算开源软件,均只提供双绕组变压器模型,限制了其在具有三绕组变压器的电力系统中的应用的问题,潮流计算是自主开发的电力系统各种应用软件的核心模块,因此依托国际权威开源程序进行二次开发,是一种较好的选择。对Matpower要求的数据格式进行了归纳,对变压器的一般的等值电路及带理想变压器的等值电路和带标幺值的等值电路进行了分析研究,提出了三绕组变压器转换为双绕组等效模型的建模方法,使得原先只适应双绕组变压器的潮流计算软件可以适用于三绕组变压器电网的潮流计算;最后以Matpower软件为例进行了案例计算,并用PSASP仿真软件进行对比验证。研究结果证明,所提出的建模方法是有效的。     

On the Relation of Load to Average Gap in the Contact Between Surfaces with Longitudinal Roughness

A computer simulation model for the contact between longitudinally-oriented rough surfaces has been formulated. This model closely duplicates the actual surf ace contact deformation behavior by taking into account the elastic interactions between the asperities. There were no assumptions made about the shapes, or any deformation behavior of the asperities, except for their obeying the laws of elasticity. The plastic deformations on the high asperity peaks were taken into account by setting a ceiling on their contact pressures at the material hardness value. The simulations used real surface profiles which were digitized from unworn circumferentially ground steel surfaces. Each pair of these profiles was mathematically combined to form an equivalent rough profile pressing against an infinitely rigid flat and having the appropriately adjusted elastic modulus. A total of 28 different pairs of profiles were used in the simulations. Each contacting pair was subjected to 30 different load levels and the local contact pressures and deformations were calculated. The contact simulations yielded some important mathematical relationships between parameters, such as the real area of contact, average gap, and average asperity load through statistical curve fitting. Two analytical functions were generated to relate the average load to average gap and the real area of contact to load.     

电站锅炉模糊风险评价方法研究与应用

针对电站锅炉风险等级评价问题,将模糊综合评价技术应用到电站锅炉风险等级评价中。开展了电站锅炉失效影响因素及模糊评价因素的重要程度分析,建立了一套科学合理适于在线评价的电站锅炉风险评价体系,提出了模糊综合评价技术与改进的模糊层次分析法相结合的模糊风险评价方法,利用改进的模糊层次分析法计算了指标体系中各层指标权重。对某一台电站锅炉的实际运行工况影响子因素进行了模糊风险评价,采用模糊合成算子进行模糊综合运算得到电了站锅炉运行工况影响子因素的评价向量。研究结果表明:电站锅炉的运行工况影响子因素的风险评价等级为第6级,失效可能性等级为小,该电站锅炉运行工况良好。     

交通荷载作用下桥梁结构参数识别方法

应用动力节点加载法,将作用在桥梁上的交通荷载转化为等效节点荷载,再用两步构造法识别结构物理参数.第1步,用Newmark-β方法变换结构运动方程,并用结构的加速度响应求得变换空间内的位移、速度和加速度响应;第2步,基于最小二乘原理,构造出变换空间内求解结构参数的递推式,进行结构物理参数识别.数值模拟结果表明,在交通荷载作用下,该方法能够快速、准确地进行桥梁结构参数识别.     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.     

Quantum Cooperative Robotics and Autonomy

The intersection of Quantum Technologies and Robotics Autonomy is explored in the present paper.The two areas are brought together in establishing an interdisci...     

OPTIMIZATION METHOD ON IMPELLER MERIDIONAL CONTOUR AND 3D BLADE

An optimization method for 3D blade and meridional contour of centrifugal or mixed-flow impeller based on the 3D viscous computational fluid dynamics (CFD) analysis is proposed. The blade is indirectly parameterized using the angular momentum and calculated by inverse design method. The design variables are separated into two categories: the meridional contour design variables and the blade design variables. Firstly, only the blade is optimized using genetic algorithm with the meridional contour remained constant. The artificial neural network (ANN) techniques with the training sample data schemed according to design of experiment theory are adopted to construct the response relation between the blade design variables and the impeller performance. Then, based on the ANN approximated relation between the meridional contour design variables and impeller performance, the meridional contour is optimized. Fewer design variables and less calculation effort is required in this method that may be widely used in the optimization of three-dimension impellers. An optimized impeller in a mixed-flow pump, where the head and the efficiency are enhanced by 12.9% and 4.5% respectively, confirms the validity of this newly proposed method.