翻车保护结构安全性能动态试验的数值仿真

为完善有限元方法在翻车保护结构(ROPS)静/动态强度仿真试验中的应用,同时能在设计阶段充分考察ROPS的安全性能,使之顺利通过相关法规的检测,以某型号拖拉机ROPS为研究对象,根据OECD标准Code-3中关于对ROPS强度试验的要求,对模型进行合理的简化,首次提出利用有限元软件ABAQUS/Explicit对ROPS后撞试验过程进行仿真.结果显示ROPS的部分区域已经发生塑性变形,最大变形发生在撞击点处,但没有侵入安全容身区,符合标准的验收条件.各部分的应力分布与实际后翻事故中拖拉机受到冲击载荷作用的受力状况较为吻合,可以作为结构改进的依据.提出的仿真方法能有效地模拟撞击试验的动态过程,可为类似工程结构的动态仿真分析提供一定的参考.     

基于ABAQUS的装载机驾驶室防滚翻安全性能分析

利用驾驶室保护结构试验台对装载机驾驶室防滚翻结构(ROPS)进行试验,利用非线性有限元软件ABAQUS对装载机驾驶室防滚翻结构(ROPS)进行了结构改进,并进行了有限元力学性能仿真分析。结果表明:原装载机驾驶室ROPS在最小垂直载荷作用下有侵入挠曲极限区域的风险,根据实验结果对ROPS进行了结构改进,改进后进行仿真分析的ROPS在满足最小垂直载荷的同时,ROPS远离挠曲极限区域DLV,驾驶室防滚翻安全性能更加符合国家标准要求。     

矿用自卸车翻车保护结构分析及侧向性能优化

根据某矿用自卸车的翻车保护结构型式,建立翻车保护结构（简称ROPS）安全性能仿真的动态有限元模型。模拟现场试验的加载过程设计加载曲线,进行动力学求解运算。仿真结果显示ROPS侧向刚度过大导致能量吸收与侧向承载力匹配不良。针对该缺陷对翻车保护结构主要承载结构进行刚度改善并重新进行动力学求解运算,仿真结果表明优化后的ROPS侧向性能得到极大地改善,有效地保障了工程车辆的安全性。     

基于有限元技术的轮式装载机ROPS分析

以ZL50C轮式装载机ROPS为研究对象,建立有限元建模并进行非线性有限元分析,获取ROPS在各种工况下的变形情况;对ROPS性能进行测试研究,并对有限元分析结果和试验结果进行对比分析。基于判定工程车辆ROPS失效准则,利用非线性有限元方法对ROPS进行理论结算。     

侧翻工况下零转弯半径割草机ROPS动态仿真

为了研究零转弯半径割草机(Zero Turning Radius Mower)在土壤斜坡上ROPS的动态响应过程以及确保驾驶员在侧翻过程中的安全,提出了对ZTR割草机整机ROPS动态仿真建模及理论分析方法,以某割草机在倾角为30°的土壤斜坡侧翻工况为例,利用多刚体动力学及弹性体模型相结合的有限元非线性分析方法进行研究,运用LS-DYNA软件对割草机ROPS进行动态仿真分析,结合理论分析和最新ISO21299(2009E)评定标准,验证了建模方法的可行性及仿真结果的合理性。仿真实验结果表明:在整车碰撞过程中ROPS的最大冲击力为22562.3N,最大变形量为43.49mm,吸收的能量值为824.7J,研究表明驾驶员不会暴露于容身空间范围之外(根据ISO21299新标准计算得到容身空间暴露时ROPS最大变形量为275mm),确保了安全性,但是研究也发现目标割草机所采用的ROPS材料(Q235)过度安全,其强度及刚度匹配有待进一步优化。     

某工程车驾驶室ROPS仿真分析及试验研究

某工程车驾驶室翻车保护结构(ROPS)是驾驶员在车辆发生翻车事故中重要的安全保障,结构可靠性对驾驶员生命安全有着不可忽视的作用。本研究通过建立某工程车驾驶室ROPS虚拟模型,根据非线性有限元接触理论,对模型进行最小侧向承载能力、最小垂直承载能力有限元分析,再对ROPS样机进行试验研究。结果表明,应用非线性有限元分析方法对ROPS理论计算是合理的。     

基于有限单元法驾驶室防翻保护结构性能分析

防滚翻保护装置（ROPS）设计的可靠性,直接影响驾驶员是否能得到有效的保护。根据实车尺寸和视野要求,进行ROPS结构设计和挠曲极限量DLV设计;利用UG建立驾驶室三维模型,并建立有限元分析模型;根据国家标准关于ROPS的规定,对驾驶室翻滚保护的安全性进行分析,重点对不同方向的承载进行分析;基于驾驶室翻滚测试试验台,选取侧向加载进行测试,验证模型分析的可靠性。结果可知：当侧向力增加到140kN时,驾驶室吸收的能量为16672J,满足最小能量吸收能力要求;侧向载荷加载时,应力和位移均出现最大值,分别为372MPa和11.86mm,满足材料承载和能量加载要求;试验获得侧向加载时的最大应力和最大位移,满足材料和设计尺寸的要求,且与仿真结果的误差均小于4%,表明仿真分析模型是可靠的。所设计的防翻保护装置可以起到保护作用,为此类设计生产提供参考。     

材料屈服极限对工程车辆驾驶室翻车保护结构有限元仿真结果的影响

以非线性有限元技术为理论基础,根据国际试验标准中力的加载方式,建立含有翻车保护结构(ROPS)的非线性有限元模型.通过Nastran的非线性分析对模型进行了最小侧向承载能力、垂直承载能力和纵向承载能力分析,比较了ROPS材料屈服极限对最小侧向承载能力变形和应力结果的影响,为后期的有限元模型修正提供了较可靠的依据.     

挖掘机翻车保护装置的计算机仿真与试验研究

简介挖掘机翻车保护结构的特点及功能要求.结合非线性有限元理论,以某挖掘机保护结构为研究对象,进行侧向和前向加载的仿真和模拟,得到翻车保护装置(ROPS)在侧向与前向加载时的载荷-位移曲线,并分析其变形规律.同时根据GB/T 19932-2005标准对此装置进行试验测试,通过与试验数据对比,验证了有限元分析的可行性,为后期的结构设计及优化提供了可靠的依据.     

挖掘机驾驶室保护和连接装置的改进

正我公司出口澳大利亚等国家的挖掘机需满足驾驶室落物保护(FOPS)和驾驶室滚翻保护(ROPS)的强制性要求。为了满足该强制性要求,提升挖掘机驾驶室的安全性能,我们在困家建筑城建机械质量监督检验中心,依据ISO10262:1998《土方机械液压挖掘机司机防护装置的实验室试验和性能要求》和ISO 12117-2:2008《土方机械挖掘机保护结构实验室试验方法和性能要求第2部分:大于6t的挖掘机翻     

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.     

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。     

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.     

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...     

考虑进油孔有限长滑动轴承油膜力的近似解析解

针对具有进油孔的有限长滑动轴承油膜力求解问题,采用变分原理和分离变量法,求得了有限长滑动轴承油膜压力分布的近似解析表达式。将油膜压力分布的近似解析表达式在油膜存在区域上进行积分,即得到了油膜力。将提出的计算有限长滑动轴承油膜力方法与无限长轴承模型、有限元方法的计算结果进行了比较,发现了提出的方法与有限元方法的计算结果很接近。最后,研究了进油孔位置和进油压力对油膜存在区域、油膜力等的影响,研究结果表明进油孔位置和进油压力对油膜存在区域和油膜力有较大的影响。     

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.