发动机活塞组的耦合有限元分析

利用Pro/E软件建立了某涡轮增压发动机活塞组的三维实体模型.通过有限元软件Hv-perMesh和ANSYS,分别完成了活塞组在机械负荷、热负荷和热力耦合作用下的有限元分析,得到了活塞的应力和变形情况,为活塞的结构改进及优化设计提供理论依据.     

基于有限元分析的汽油发动机密封性能多物理场耦合研究

以某典型汽油发动机的气缸盖、气缸垫及气缸体组合结构为例,基于ANSYS Workbench平台全面模拟汽油发动机的工作状况,对其进行流体场、瞬态温度场以及瞬态结构场的多物理场耦合分析,获得汽油发动机冷却液速度、组合结构温度和应力、气缸垫变形,并探讨热载荷、机械载荷对汽油发动机密封性能的影响。结果表明,发动机组合结构在热载荷、机械载荷的共同作用下,发动机燃烧室所承受的等效应力较大且其变化较明显,气缸垫缸口处压纹变形也较明显,可通过调整燃烧室的水套结构、冷却液流速来降低等效应力,以及调整气缸垫的压纹结构、螺栓预紧力来降低气缸垫的变形,从而达到发动机密封性能提高的目的。     

液压缸承受径向载荷的非线性有限元分析

针对工程实际应用,运用ANSYS软件建立了承受径向载荷的液压缸的有限元模型,通过有限元分析得到了液压杆、活塞、导向套和缸筒的应力及变形后的间隙,保证了液压缸在承受径向载荷时的安全性.     

柴油机钢头铁裙组合活塞有限元计算分析

应用有限元分析软件ANSYS对柴油机钢头铁裙组合活塞进行了热分析、结构分析及热一结构耦合分析,获得了活塞在实际工作条件下的温度分布、应力分布及变形情况。计算结果对活塞结构设计改进具有重要指导意义。     

柴油机活塞有限元分析与结构改进

活塞是发动机中工作情况最为恶劣的零部件之一.对495柴油机活塞的温度、热应力及变形、机械应力及变形进行了分析,并给出了活塞的热、机械耦合应力与变形,针对分析结果指出了活塞结构的改进方向.该分析可为类似发动机活塞的分析与结构改进提供理论参考与实践指导.     

不同条件下发动机活塞的热力学分析

本文的发动机活塞热力分析是基于电阻-电容模型的,在不同边界的条件下,使用MATLAB软件进行计算,然后使用ANSYS软件对活塞进行热力性分析,最后比较不同边界条件下发动机活塞的热力性,研究在不同边界条件温度及压力对活塞的影响。结果表明,由于可利用的方程数量较少,因此基于电阻-电容模型进行不同边界条件下的活塞热力性分析是解决发动机活塞传热问题的合适方法。在后半部分中,使用ANSYS软件分析了由于温度分布不均匀导致的热应力以及机械载荷引起的机械应力,最后,将温度分布作为热负荷以及机械负荷施加到活塞上以确定总应力分布和临界断裂区域。     

C形双面组合密封装置密封性能分析

为进一步研究C形双面组合密封圈在往复运动中的密封特性,基于力学和有限元理论,以活塞处C形双面密封圈为研究对象,利用三维软件建立C形双面密封装置结构模型,利用有限元分析软件ANSYS仿真分析空载工况下不同过盈量和受载工况下不同介质压力对C形双面密封圈的应力和变形的影响。结果表明:空载工况下应力和变形随着过盈量增大而增大,最大变形出现在靠近与缸壁接触处;负载工况下应力和变形随着介质压力增大而增大,且应力均集中于密封圈上下部,而最大变形区域出现在密封圈进油口下部。     

发动机活塞温度场Я热应力与热变形仿真分析

利用PRO/E软件建立活塞几何模型,并借助ANSYS有限元分析软件对活塞温度场进行有限元计算和分析,得到活塞的三维温度场分布情况。并在此基础上分析活塞的热应力及热变形,确定活塞失效的主要位置,从而为改进设计提供参考。     

阀门中法兰瞬态温度波动密封性能研究

根据传热学理论建立传热学模型,运用ANSYS有限元分析软件建立三维有限元模型和温度场,以瞬态温度场和热-结构耦合为基础,研究了不同升温速度对垫片密封性的影响。结果表明:受温度影响产生的热应力会造成法兰接头各元件应力及变形的变化,并且一定程度上会加剧垫片应力不均匀;并且升温速度越快,垫片应力下降越快,变形量增加越快,对密封造成的不良影响越大。另外本文还采用瞬态温度场对温度波动工况进行了研究,结果表明,温度波动会导致垫片内外侧变形增大而应力减小,大大降低密封可靠性。     

基于Pro/E和ANSYS Workbench的四缸发动机曲轴有限元模态分析

曲轴是发动机的重要组成部分,其振动特性对整个发动机的NVH有重大影响。本文采用三维设计软件Pro/E,建立四缸发动机曲轴的三维实体模型,利用ANSYS Workbench软件对曲轴进行模态分析,得到其固有频率和振型。这不仅为曲轴的设计避开共振提供了一定的参考,而且为曲轴的优化和改进设计提供了理论依据,并有助于曲轴的瞬态动力学分析,以及变负荷瞬态工况下曲轴的受力情况、应力与疲劳寿命预测的求解。     

Minimal Realization of Linear Graph Models for Multi-physics Systems

An engineering system may consist of several different types of components,belonging to such physical"domains"as mechanical,electrical,fluid,and thermal.It is t...     

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。     

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...     

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。     

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。     

Fifth International Summer School on Screw-Theory Based Methods in Robotics

正3-11 September,2014University of Bologna,Bologna,Italy www.summerscrews.org summerscrews2014.ing.unibo.it SUMMER 20SCREWS 14In 2014,our screw-theory school comes to the world's oldest university.In early September,Summer Screws'14 will gather six experts in the application of screw theory in robotics and up to 40 participants at the University of Bologna,Bologna,Italy.The school will teach attendees how to apply existing methods and empower them to develop new ones in their own research.The basic theoretical notions will be introduced in a rigorous manner,emphasizing examples,applications,and exercises.Scholarships are available.     

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.     

INDUSTRIAL ENGINEERING AND VISUALISATION-A PRODUCT DEVELOPMENT PERSPECTIVE

Taking the actual project of teaching and researching process for example, the relationship between the industrial engineering and product development is discussed. And use the novel visualization technology to support the industrial engineering and product development. How to use the new computer modeling and simulating technologies to support the product development and industrial engineering, is introduced especially. The support includes both domestic products and industrial systems. The visualization and computer technologies take a very important role in some system or multi-direction modeling, those technologies mentioned above can help the industrial engineers study the effect of design on the whole life circle, including the producing steps. So the engineers can avoid making the wrong decision which may cause bad effects on the whole industrial engineering.     

Non-monotonic material contrast in scanning ion and scanning electron images

30 keV Ga⁺ focused ion beam induced secondary electron (iSE) imaging was used to determine the relative contrast between several materials. The iSE signal compared from C, Si, Al, Ti, Cr, Ni, Cu, Mo, Ag, and W metal layers does not decrease with an increase in target atomic number Z₂, and shows a non-monotonic relationship between contrast and Z₂. The non-monotonic relationship is attributed to periodic fluctuations of the stopping power and sputter yield inherent to the ion–solid interactions. In addition, material contrast from electron-induced secondary electron (eSE) and backscattered electron (BSE) images using scanning electron microscopy (SEM) also shows non-monotonic contrast as a function of Z₂, following the periodic behavior of the stopping power for electron–solid interactions. A comparison of the iSE and eSE results shows similar relative contrast between the metal layers, and not complementary contrast as conventionally understood. These similarities in the contrast behavior can be attributed to similarities in the periodic and non-monotonic function defined by incident particle–solid interaction theory.