基于有限元技术和试验模态的方向盘优化设计

文章针对某款乘用车在怠速工况下的方向盘振动问题进行了怠速振动试验,系统分析了引起方向盘振动的主要因素,利用有限元分析方法寻找最佳的优化方案以提高转向系统模态。对比优化前后的试验数据,方向盘的振动加速度得到明显改善。     

基于试验模态的方向盘振动控制优化

为解决某中型客车怠速方向盘振动过大问题,采用试验模态分析法,运用BK测试系统分析发现方向盘振动过大的主要原因.通过更换刚度更大方向盘提高固有频率的措施,避免发动机的怠速频率与转向管柱共处半功率频带,从而改善怠速方向盘振动过大的问题.试验验证表明:方向盘怠速振动峰值降低51.4%,达到预期效果,提高车辆的驾驶舒适性并为解决同类问题提供一个可行方法.     

考虑定子各向异性的永磁同步电机振动噪声优化

为了有效降低永磁同步电机的振动和噪声,在考虑定子各向异性建模的基础上,提出了一种通过定子结构模态规划来优化振动噪声的方法。首先分析了对定子模态频率较为敏感的各向异性材料参数,通过定子铁芯和总成的模态试验进行了参数识别;随后分析了电机在额定工况下的振动和噪声峰值来源,并且在电磁力二维分解的基础上提出了降低电机噪声的模态规划目标;最后分析了主要结构参数对定子模态频率的灵敏度,最终选择定子轭部厚度作为优化参数来实现模态频率的规划。研究结果表明:通过考虑定子材料的各向异性可以建立较为准确的定子模型,模态频率计算值与实测结果的误差都在4%以内;仿真优化后的电机振动峰值下降了58%,总体噪声功率级(A)降低了4.3dB。     

大型立式电动机转子系统模态仿真与振动实验研究

根据电磁耦合理论和电动机的实际工作情况,建立YKSL1730型电动机转子系统的虚拟样机模型,确定模型的载荷和约束。应用有限元仿真系统Msc.Nastran,对该转子系统进行有限元模态分析,获得前3阶固有频率及其振型云图,分析转子变形的分布规律,确定转子在前3阶固有模态下振动的主要危险部位。同时,应用DH5922动态信号测试分析系统对YKSL1730型立式电动机进行振动试验,获得空载工况下的一系列时域信号;通过信号的频谱分析,获得该型立式电动机前3阶固有频率的实验值。研究结果表明:仿真试验结果与理论分析结果很接近,仿真结果可为立式电动机的结构设计与减振降噪提供理论依据;增加转子系统的刚度,可减小转子及其铁芯端部的变形,提高电机运行的平稳性和安全性。     

XMQ6838Y客车动力总成悬置系统参数的优化设计

针对XMQ6838Y客车怠速时方向盘抖动和座椅振动剧烈的问题,以其动力总成悬置系统各阶模态的解耦率最大为目标和固有频率的分配为约束,构建一种以悬置元件离散刚度与连续位置为设计变量的优化设计模型.通过建立系统自由振动模型,获取其固有频率和六阶模态;利用能量解耦法,求解系统六自由度的解耦率.在MATLAB和iSIGHT集成条件下,采用刚度离散化的方法和自适应模拟退火算法,优化悬置系统设计参数.实验结果表明:优化后,该车型在启、闭空调时方向盘和各排座椅的三向振动均明显降低,尤其在开启空调时,方向盘Y向振动加速度由3.43 m·s^-2下降至0.35 m·s^-2,提升了乘坐舒适性.     

集成驱动式结构的永磁同步电机振动噪声特性

以电机-减速器集成化的电动车动力总成为研究对象,建立了动力总成有限元模型,并对比了有无减速器结构时的电机模态.分析了电动车动力总成振动噪声的产生机理,综合考虑齿轮动态啮合激励以及电机电磁激励,对动力总成进行动态响应数值仿真分析.通过频域分析研究了系统的振动噪声特性,得到了集成化结构对电机动态特性的影响.对动力总成进行声振试验,验证了理论与仿真分析所得结论的正确性.结果表明:集成减速器后,电机的模态和振动噪声特性均会发生变化.     

发动机激励下客车车身怠速振动仿真研究

以某国产客车为研究对象,综合运用多体动力学和有限元分析法来研究发动机激励下车身的动态响应。在多体动力学软件MotionView中建立整车的动力学模型,在有限元软件 HyperMesh中建立车身有限元模型,用MotionSolve求解发动机激励引起的动力总成悬置系统的动载荷,将悬置系统的三向动载荷施加到有限元模型上,用RADIOSS定量求解出车身特征点的动态响应。以发动机怠速工况为例,将车身特征点振动加速度均方根值的仿真计算结果与实车测试结果进行对比分析,验证仿真方法的正确性。结果表明,将多体动力学仿真和有限元仿真有机结合起来研究发动机怠速激励下客车车身的动态响应是行之有效的。     

三轮越野叉车车身的有限元分析法

对三轮越野叉车车身的工作机理进行了分析,采用有限元方法,借助计算机仿真软件Ansys,建立了车身系统的有限元模型,对车身进行了应力应变分析和振动模态分析,得出了叉车在静力和振动条件下的危险工作部位,为叉车设计与优化提供了理论依据.     

整体叶盘结构模态特性分析及应力分布规律

为了研究整体叶盘结构的模态特性及应力分布规律,基于有限元分析方法建立了整体叶盘结构有限元仿真模型,对自由状态及离心力载荷下的整体叶盘进行模态及振动特性分析;并探究实心与空心整体叶盘的应力分布差异及不同叶片间隙的整体叶盘应力分布规律。为了验证仿真结果的准确性,基于多点激励单点响应方法开展了整体叶盘结构模型的模态试验,并在多功能转子实验台上开展不同转速下应力测试试验。结果表明,该结构模态频率的仿真结果与试验测试结果误差在4%以内,验证了所建立的有限元仿真模型的正确性;应力测试试验验证了其不同转速下的应力分布规律;离心力载荷对整体叶盘二节径振动下固有频率影响最为显著;空心叶盘较实心叶盘应力集中现象更为突出,且叶片根部应力值会随着叶片间隙的增大而有明显提高。     

某商用车前照灯怠速振动控制研究

针对某商用车怠速时前照灯抖动的问题,研究了前照灯产生怠速抖动的机理。对激励源和传递路径进行了测试分析;并利用CAE仿真技术对前照灯总成模块进行固有频率及振型分析。仿真分析表明,前照灯总成模块与激励频率重叠而发生了共振。通过CAE仿真分析,提出了在前照灯与下防护之间增加支撑的优化方案。仿真结果表明,优化后的固有频率与激励频率之间的间隔在6 Hz以上,避开了激励频率,有效地解决了前照灯怠速工况下的抖动问题。实车测试验证了该方案的有效性。     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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