微观织构配流副热-流-固耦合润滑特性

通过建立轴向柱塞泵配流副的几何模型,利用雷诺方程推导了配流副的油膜压力方程,采用有限差分法和松弛迭代法求解雷诺方程。利用FORTRAN语言编程求解,利用MATLAB语言对油膜厚度、压力、温度分布进行了仿真研究。结合油膜厚度方程、雷诺方程、能量方程、弹性变形方程、黏温黏压方程和密度温压方程,仿真微观织构配流副的热弹流润滑特性。研究表明：配流副油膜厚度增大,最大油膜压力减小,最高温度值减小;配流副的热-流-固耦合效果随油膜间隙收敛逐渐明显,在最小油膜厚度处达到最大,并且,油膜压力值达到最大;加工微观织构可以显著改变配流副的油膜压力和温度分布。     

锥形缸体球面配流副润滑特性建模及试验验证

配流副油膜的润滑特性对轴向柱塞泵的可靠运行有重要影响。建立了锥形缸体球面配流副油膜润滑特性仿真模型,并通过试验验证了模型的有效性。对锥形缸体进行受力分析,通过对柱塞滑靴组件运动学和受力的分析,求解得到柱塞滑靴组件对锥形缸体的作用力;通过对球面配流副油膜厚度分布和压力分布的分析,求解得到球面配流副对锥形缸体的油膜支承力;采用有限容积法对油膜进行离散化处理,通过牛顿迭代法数值求解球面配流副油膜润滑特性和锥形缸体运动方程;开展轴向柱塞泵高压稳态试验和轮廓扫描试验,获得不同稳态试验时长的球面配流盘磨损形貌,对比球面配流盘磨损轮廓与仿真得到的油膜厚度分布和压力分布。研究结果表明,仿真得到的油膜厚度较小区域与配流盘主要磨损区域相近,验证了锥形缸体球面配流副油膜润滑模型的有效性。     

轴向柱塞泵配流副短阻尼孔效应研究

在间隙径向压力对数分布的条件下,进行了短阻尼孔型配流副静压支承的受力分析,得出了油膜厚度是工作压力、结构系数及油液粘度的函数;建立了配流副静压支承在突变载荷下的动态方程和模型,对静压支承的动态特性进行了仿真研究,仿真结果表明短阻尼孔型配流副静压支承具有较好的动态特性,且油膜厚度能在很短时间内恢复到平衡位置,具有很小的超调量.     

轴向柱塞泵配流副油膜试验原理及控制特性

为研究油、水介质下轴向柱塞泵几类关键摩擦副的润滑特性,提出采用电液单元对润滑油膜进行主、被动控制的专用试验系统原理。论述该试验系统用油膜厚度反馈控制配流副密封间隙的模拟试验装置的原理与构成,将微缝隙流对电液控制系统的作用简化为弹簧中阻尼器负载,建立配流副对润滑油膜厚度的阀控缸物理模型并推导精密缸位移控制方程,分析影响润滑性能的主控参量及相互关系,仿真研究油膜厚度控制的动态特性。运用该试验系统进行了初步的平面配流副油膜试验。研究表明,油膜平衡的仿真与试验基本一致,供油压力、摩擦转矩等对润滑油膜的形成影响较大。伺服比例阀的反馈控制原理使系统的油膜厚度动态反馈性能趋于稳定,但在供油压力斜坡变化时油膜厚度平衡值在设定范围内有一定变化。     

内螺纹织构深度对涡轮增压器浮环轴承油膜动态特性的影响*

浮环轴承内螺纹织构深度会改变织构区域油膜厚度，导致浮环轴承油膜动态特性变化，从而影响涡轮增压器转子-轴承系统运行稳定性以及工作寿命。基于流体润滑理论，推导含表面织构的浮环轴承油膜控制方程，揭示内螺纹织构深度与浮环轴承油膜特性之间的关系。以某型涡轮增压器浮环轴承为例，分析内螺纹织构深度对轴承油膜最大压力、油膜承载力、刚度、阻尼等的影响。建立浮环轴承双油膜润滑分析流体动力学模型，利用CFD方法对油膜动态特性进行分析，研究织构深度从6 μm增至12 μm时的油膜特性。结果表明：在轴颈转速1×103~2.1×105 r/min范围内，随着织构深度的增加，油膜最大压力、内外油膜承载力、刚度阻尼系数呈现先增大后减小的趋势；在转速超过1×105 r/min后，织构对油膜动态特性系数提升更明显；与无织构轴承相比，织构深度为8 μm时，油膜承载力、刚度阻尼等动态特性提升最大。研究表明，在合适的织构深度下，织构可以改善油膜特性，提升轴承的运转稳定性，延长工作寿命。     

球面配流副油膜的几何成型计算

以球面配流副为研究对象,通过引入欧拉角来表征缸体位姿,建立起球面配流副油膜分布的数学模型,从而获得油膜二维厚度值分布图以及三维球面分布图;进一步,在考虑实际配流副几何空间限制的约束下,建立基于球面油膜厚度空间的优化模型,通过GAS算法获得了油膜空间最小和最大油膜厚度以及所在位置.研究表明,缸体姿态对油膜几何场分布影响显著,为进一步研究油膜流场分布奠定了基础.     

不同微观织构柱塞泵配流副润滑特性研究

建立不同造型的微观织构柱塞泵配流副润滑油膜控制方程,采用有限差分法对其进行了求解,分别对比分析正方形、三角形、圆柱形、波浪形、球冠形微观织构的油膜负载能力等润滑特性;随转速变化,微观织构对其油膜负载力、油膜厚度、摩擦力等影响。随转速升高,流体动压压力升高,但并不是线性关系。     

柱销式叶片泵配流副功率损失和最佳轴向间隙研究

根据柱销式叶片泵配流副几何特征和运动特性,从油液泄漏和黏性摩擦两个方面分析,建立了柱销式叶片泵配流副功率损失计算模型。在泵结构参数和工况参数一定情况下,通过最小功率损失计算,得到配流副最佳油膜厚度计算公式,并结合实际加工可操作性给出配流副最佳轴向间隙选择方法。分析了变工况下动力黏度、负载压力和转速对最佳油膜厚度的影响,发现低压时油液动力黏度对最佳油膜厚度分布影响最为明显。研究结论对柱销式叶片泵配流副轴向间隙尺寸设计有一定指导意义。     

不同转速下齿轮动力学与油膜润滑耦合研究

为探究齿轮振动时油膜的动态特性,考虑齿轮时变啮合刚度的激励作用,基于动力学理论,建立齿轮系统动力学模型,分析齿轮系统的弹流润滑特性;同时,基于弹流润滑数值解,建立油膜的刚度模型,进行不同转速下齿轮动力学与油膜润滑的耦合研究。研究表明:基于动力学模型进行弹流润滑的求解时,油膜厚度表现出一定的动态特性,且不同齿轮转速下的振幅和振动频率不同;随着齿轮转速的增大,油膜的刚度减小,对于高速重载的齿轮系统,油膜润滑对其振动特性有较大的影响,应当将齿轮振动与油膜润滑视为整体进行研究。     

不同织构几何参数对轴向柱塞泵配流副动压支承的影响研究

针对轴向柱塞泵配流副的减摩降噪问题,将仿生学表面织构技术引入织构化配流副的研究,对织构化配流副瞬态受力进行分析,得出了瞬态受力动压方程;建立了矩形、圆弧形、三角形、等腰梯形四种典型织构的二维流场简化模型,运用Fluent仿真软件,得到四种织构都能产生动压支承,其中矩形织构的动压力最大;矩形织构和圆弧织构的最佳深径比都为1∶5,三角织构和等腰梯形织构的最佳深径比为1∶4,其中四种典型织构的动压力都随织构深径比的增加都呈现先增大后减小的变化规律,深径比对圆弧织构、等腰梯形织构的动压影响较小,矩形、三角形织构对深径比的变化较敏感,并且两个织构的富集将产生二次动压支承,因此,找到典型单织构的最佳深径比和织构富集的数目对织构化配流副减摩降噪相当关键。     

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.     

INTEGRAL EQUATION METHOD＇S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES

The strength of composite plate with different hole-shapes is always one of the most important but complicated issues in the application of the composite material. The holes will lead to mutations and discontinuity to the structure. So the hole-edge stress concentration is always a serious phenomenon. And the phenomenon makes the structure strength decrease very quickly to form dangerous weak points. Most partial damage begins from these weak points. According to the complex variable functions theory, the accurate boundary condition of composite plate with different hole-shapes is founded by conformal mapping method to settle the boundary condition problem of complex hole-shapes. Composite plate with commonly hole-shapes in engineering is studied by several complex variable stress fimction. The boundary integral equations are founded based on exact boundary conditions. Then the exact hole-edge stress analytic solution of composite plate with rectangle holes and wing manholes is resolved. Both of offset axis loadings and its influences on the stress concentration coefficient of the hole-edge are discussed. And comparisons of different loads along various offset axis on the hole-edge stress distribution of orthotropic plate with rectangle hole or wing manhole are made. It can be concluded that hole-edge with continuous variable curvatures might help to decrease the stress concentration coefficient; and smaller angle of outer load and fiber can decrease the stress peak value.     

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.