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On the Spontaneous Electric Field in a Ferroelectric Body

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Journal of Modern Transportation 1998年第2期15卷 39-49页

作者：张颖

The incompatibility of the spontaneous polarization across the interface between two grains may induce internal stress and electric fields in a ferroelectric body. The built up of stresses and electric fields may seriously affect the functioning of ferroelectric materials. In this article, the effects of the incompatibility of the spontaneous polarization for various types of interfaces on the electric fields are discussed. Numerical results indicate that the incompatibility of the spontaneous polarization may result in the electric field being unbounded when the interface does not have a continuous normal.

关键词： ferroelectrics spontaneous polarization electric field

Experimental Research on Behavior of Composite Material Projectile Penetrating Concrete Target

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Transactions of Tianjin university 2008年第6期14卷 430-433页

作者：钟卫洲宋顺成张方举张青平黄西成李思忠卢永刚 Department of applied mechanics and Engineering Southwest Jiaotong University institute of Structural mechanics China Academy of Engineering Physics

Projectile made of carbon fiber composite material shell and metal warhead penetrates concrete target at speeds of 336,m/s,447,m/s and 517,m/*** angles between the perpendicu-lar of target surface and projectile axis are 0°and 30°.The thickness of concrete target is 200,mm and the compression strength is 30 *** experimental results indicate that the strength of composite material structure is *** projectile can go through concrete tar-get without fiber segregation and *** percent fill is 18.5% in the composite material *** is about twice as that of metal projectile,if the density of metal is taken as 7.8,g/*** with metal projectile,low-density,high-strength composite material can lessen projec-tile weight,improve charge-weight ratio of detonator and enhance destructive powder.

关键词： composite material penetrating carbon fiber concrete

人工髋关节超高分子量聚乙烯高边衬垫的接触力学和边缘负载

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清华大学学报（自然科学版） 2024年第3期64卷 442-453页

作者：冯涛张小刚张国贤谢庆云张亚丽靳忠民西南交通大学机械工程学院摩擦学研究所成都610031 中国人民解放军西部战区总医院成都610083

全髋关节置换术后衬垫边缘出现边缘负载不仅会增加脱位风险,而且会加剧假体的摩擦磨损。发生边缘负载与假体的安装位置、几何设计及患者运动状态等高度相关。该文基于金属-聚乙烯接触副建立了髋关节高边衬垫在步态载荷下的接触力学和边... 详细信息

全髋关节置换术后衬垫边缘出现边缘负载不仅会增加脱位风险,而且会加剧假体的摩擦磨损。发生边缘负载与假体的安装位置、几何设计及患者运动状态等高度相关。该文基于金属-聚乙烯接触副建立了髋关节高边衬垫在步态载荷下的接触力学和边缘负载的有限元分析模型。该模型考虑了日常生活中正常行走、上楼梯、下楼梯和深蹲4种步态及20种相对极端的臼杯安装位置,以研究高边衬垫的接触应力、边缘负载和等效塑性应变情况。结果表明:衬垫的等效塑性应变、发生塑性变形的体积、边缘负载和边缘负载的持续时间都随臼杯外展角和前倾角增加而增加;相比于另外3种步态,深蹲步态更容易使衬垫产生塑性形变,对衬垫造成的破坏最大;在臼杯外展角不低于50°的情况下,将高边衬垫的高边放置于人体后上方不但能避免出现边缘负载,还能显著降低衬垫的塑性应变。

关键词：接触力学人工髋关节边缘负载超高分子量聚乙烯高边衬垫

基于多分辨率技术及奇异值理论的故障检测方法

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系统工程与电子技术 2002年第4期24卷 37-40,57页

作者：李世玲李治张富堂西南交通大学电气工程学院四川成都610031 中国工程物理研究院电子工程研究所四川绵阳621900

提出了以小波多分辨率技术与矩阵奇异值理论相结合的故障检测方法。根据小波变换的多分辨率分解特性 ,提出了系统状态观测信号的二初始特征向量矩阵———粗分辨逼近矩阵和边缘细节信息矩阵。利用矩阵奇异值分解理论得到初始特征向量矩... 详细信息

提出了以小波多分辨率技术与矩阵奇异值理论相结合的故障检测方法。根据小波变换的多分辨率分解特性 ,提出了系统状态观测信号的二初始特征向量矩阵———粗分辨逼近矩阵和边缘细节信息矩阵。利用矩阵奇异值分解理论得到初始特征向量矩阵的奇异值 ,将其作为状态信号的特征向量。针对提取出的系统状态信号奇异值特征 ,设计出相应的故障检测算法 ,并将该方法用于某武器平台上精密弹簧阻尼器的故障检测。仿真结果证实了该方法的正确性和有效性。

关键词：多分辨率技术奇异值理论故障检测方法

Effect of geometry simplification and boundary condition specification on flow field and aerodynamic noise in the train head and bogie region of high-speed trains

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Journal of Zhejiang university-Science A(applied Physics & Engineering) 2024年第9期25卷 716-731页

作者： Jiawei SHI Yuan HE Jiye zhang Tian LI State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China institute of Sound and Vibration Research Faculty of Engineering and Physical SciencesUniversity of SouthamptonSouthampton SO171BJUK

The purpose of this study is to determine a suitable modeling method to make computational fluid dynamics(CFD)simulation more efficient for aeroacoustics optimization of the bogie region of high-speed *** this end,four modeling methods are considered,which involve different geometry simplifications and boundary condition *** corresponding models are named the three-car marshalling model,computational domain shortening model,carbody shortening model,and sub-domain *** the detached eddy simulation(DES)model and Ffowcs Williams-Hawkings(FW-H)equation,the unsteady flow field and far-field noise of the four models are *** evaluate the effect of the different modeling methods,the time-averaged flow field,fluctuating flow field,and far-field noise results of the four models are compared and analyzed in detail with the results of the three-car marshalling model used as basis for *** results show that the flow field results of the bogie region predicted by the four models have relatively high ***,the usage of the non-time varying outlet boundary conditions in the computational domain shortening model and sub-domain model could affect the pressure fluctuation on the upstream carbody *** only the bogie region is used as the source surface,the differences between the far-field noise results of the three simplified models and the three-car marshalling model are all within 1 dB;when the train head is used as the source surface,the results of the carbody shortening model and the three-car marshalling model are more consistent.

关键词： Bogie region Train head Flow field Aerodynamic noise Geometry simplification Boundary conditions

A review of the bio-tribology of medical devices

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Friction 2022年第1期10卷 4-30页

作者： xiaogang zhang Yali zhang Zhongmin JIN School of Mechanical Engineering Southwest Jiaotong UniversityChengdu 610031China School of Mechanical Engineering Xi'an Jiaotong UniversityXi'an 710049China School of Mechanical Engineering University of Leeds.Leeds LS29JTUK

Numerous medical devices have been applied for the treatment or alleviation of various *** issues widely exist in those medical devices and play vital roles in determining their performance and service *** this review,the bio-tribological issues involved in commonly used medical devices are identified,including artificial joints,fracture fixation devices,skin-related devices,dental restoration devices,cardiovascular devices,and surgical *** current understanding of the bio-tribological behavior and mechanism involved in those devices is *** advances in the improvement of tribological properties are *** and future developments for the prospective of bio-tribological performance are highlighted.

关键词： bio-tribology medical devices wear friction

铁路起重机伸缩臂可靠性分析的随机有限元方法研究

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铁道学报 2000年第5期22卷 17-20页

作者：靳慧张仲鹏王金诺王立彬西南交通大学机械工程研究所四川成都610031 石家庄铁道学院河北石家庄050043

结合板壳元 ,在载荷随机的情况下 ,给出了利用随机有限元计算大型、复杂结构可靠度的方法 ,推导了相应的计算公式 ,计算了 QTJS1

关键词：铁路起重机伸缩臂随机有限元可靠性板壳元

Transfer relation between subgrade frost heave and slab track deformation and vehicle dynamic response in seasonally frozen ground

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Journal of Zhejiang university-Science A(applied Physics & Engineering) 2024年第2期25卷 130-146页

作者： Juanjuan REN Junhong DU Kaiyao zhang Bin YAN Jincheng TIAN MOE Key Laboratory of High-speed Railway Engineering Southwest Jiaotong UniversityChengdu610031China School of Civil Engineering Southwest Jiaotong UniversityChengdu610031China School of Civil Engineering Central South UniversityChangsha410075China Airport Planning and Design institute POWERCHINA Kunming Engineering Corporation LimitedKunming650051China

Subgrade frost heave in seasonally frozen ground can greatly influence the safety and smooth running of high-speed trains and the service performance of track *** this study,we used a static model to:(1)investigate track-subgrade frost heave and develop a dynamic model of vehicle-track-subgrade frost heave;(2)explore the transfer relation between subgrade frost heave and track structure deformation;(3)examine the characteristics of interlayer debonding;(4)study the influence of subgrade frost heave on the dynamic response of vehicles in high-speed railways in seasonally frozen regions.A Fourier series was used to fit the frost heave waveform and simulate the behavior of subgrade uneven frost heave using data collected *** results show:(i)The position of frost heave significantly affects the transfer of deformation to a slab *** largest deformation of the track slab,with the amplitude transfer ratio reaching 20%,was recorded when the frost heave occurred near the joint of the base plate.(ii)At the same frost heave amplitude,long-wave frost heave causes smaller deformation and debonding of the track structure than short-wave frost *** the wavelength range of 10-30 m,the main frequency of the acceleration spectral density was concentrated between 3.5 and 3.7 Hz,with larger frost heave wavelengths producing smaller superposition on the vertical acceleration of the vehicle.(ii)The maximum wheel-rail force occurs when the front bogie passes the frost heave peak,with greater frost heave amplitudes producing greater wheel-rail *** these results,we conclude there is a clear need to control the frost heave deformation of the track to reduce the dynamic response of the vehicle and in turn improve train operatSubgrade frost heave in seasonally frozen ground can greatly influence the safety and smooth running of high-speed trains and the service performance of track *** this study,we used a static model to:(1)investigate track`-subgr

关键词： Slab track Subgrade frost heave Transfer relation Vehicle-track-subgrade coupling Dynamic response

Integration of bio-inspired limb-like structure damping into motor suspension of high-speed trains to enhance bogie hunting stability

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Railway Engineering Science 2024年第3期32卷 324-343页

作者： Heng zhang Liang Ling Sebastian Stichel Wanming Zhai State Key Laboratory of Rail Transit Vehicle System Southwest Jiaotong UniversityChengdu 610031China Department of Engineering mechanics KTH Royal Institute of TechnologyStockholmSweden

Hunting stability is an important performance criterion in railway *** study proposes an incorporation of a bio-inspired limb-like structure(LLS)-based nonlinear damping into the motor suspension system for traction units to improve the nonlinear critical speed and hunting stability of high-speed trains(HSTs).Initially,a vibration transmission analysis is conducted on a HST vehicle and a metro vehicle that suffered from hunting motion to explore the effect of different motor suspension systems from on-track ***,a simplified lateral dynamics model of an HST bogie is established to investigate the influence of the motor suspension on the bogie hunting *** bifurcation analysis is applied to optimize the motor suspension parameters for high critical ***,the nonlinear damping of the bio-inspired LLS,which has a positive correlation with the relative displacement,can further improve the modal damping of hunting motion and nonlinear critical speed compared with the linear motor suspension ***,a comprehensive numerical model of a high-speed train,considering all nonlinearities,is established to investigate the influence of different types of motor *** simulation results are well consistent with the theoretical *** benefits of employing nonlinear damping of the bio-inspired LLS into the motor suspension of HSTs to enhance bogie hunting stability are thoroughly validated.

关键词： High-speed train Hunting stability Bio-inspired limb-like structure Motor suspension Nonlinear damping