涡旋压缩机曲轴转子壳体耦合动力学研究

以涡旋压缩机转子和壳体为研究对象,基于涡旋压缩机的总体结构和工作原理,通过对涡旋压缩机转子受力状态分析,建立了涡旋压缩机转子的动力学模型.利用有限元方法和多体动力学理论,对涡旋压缩机转子和壳体进行了有限元模态分析,获得了涡旋压缩机转子和壳体的固有频率和振型等模态特性参数.在涡旋压缩机主轴系拓扑构型的基础上,分别建立了主轴系的多刚体模型和多柔体模型.通过对曲轴系多体动力学分析,得到了气体力载荷和在柔性体条件下壳体承受主副轴承载荷等,分析了壳体在载荷作用下的动力学响应问题.结果表明,主轴和壳体主轴承之间的相互作用关系只有多柔体动力学模型能给出合理且相对准确的分析计算结果.通过壳体动态响应分析,不仅可以掌握壳体的位移与应力分布情况,而且还获得了壳体某一节点在运行过程中的位移时间历程,为主轴与壳体的结构设计提供理论依据.     

基于虚拟样机技术的压缩机曲轴动态特性研究

结合多体动力学和有限元方法对大型往复压缩机曲轴的动态特性进行了分析,建立了压缩机曲轴系动力学模型,分析得出了压缩机曲轴动态响应分析所需要的激励,并在这些激励力作用下计算其曲轴的振动响应,获得曲轴的位移应力分布情况,从而为曲轴机体的结构优化提供理论依据.     

全平衡曲轴轴系扭振分析研究

以某6列全平衡曲轴为例,利用UG建立曲轴轴系的三维模型,利用有限元分析软件ANSYS Workbench对模型进行有限元分析。通过对曲轴的静力学分析,找出曲轴最大应力点的所在位置;通过对曲轴的模态分析,得到模态振型。研究结果为大型往复式压缩机轴系的开发和设计提供了有效的理论依据。     

往复式活塞隔膜泵曲轴的动态特性分析

介绍了往复式活塞隔膜泵的结构及工作原理,建立了隔膜泵曲轴有限元模型,利用AN-SYS有限元软件对隔膜泵曲轴进行了应力计算与模态分析,得出最大应力、可能产生断裂的位置及前10阶固有频率.由分析结果知曲轴结构强度安全可靠,工作频率远远低于曲轴的各阶固有频率,所以隔膜泵曲轴因振动引起破坏的可能性很小.研究分析结果为该类产品进一步优化设计提供了理论依据.     

基于ANSYS Workbench的往复压缩机曲轴模态分析

曲轴是压缩机的关键部件之一,其振动特性严重影响压缩机使用寿命及安全性。为研究压缩机曲轴的固有振动特性,论文采用计算模态的分析方法,应用Solidworks建立了曲轴三维模型并在Workbench中进行了网格划分。对所建模型采用ANSYS软件进行有限元分析,得到了压缩机曲轴的前八阶模态的固有频率和振型,确定了可能引发曲轴共振的频段。通过合理设计避开这些频段值,可以有效提高压缩机的使用寿命。     

基于ANSYS的某型四缸内燃机曲轴模态分析

曲轴是内燃机的重要零部件,它对内燃机的动态特性影响很大。本文用ANSYS软件对曲轴进行自由模态分析,求出了曲轴在的前10阶模态的固有频率和振型。首先对曲轴进行简化,利用Pro/E建立曲轴的三维模型;然后导入ANSYS中进行有限元网格划分;最后对曲轴进行自由模态分析,得出曲轴的固有频率和振型,为发动机曲轴的优化设计和动力学分析提供了有价值的理论依据。     

往复式活塞压缩机曲轴系统运动学和动力学仿真研究

针对某型号四缸往复式活塞压缩机,基于有限元软件Ansys建立了曲轴和活塞销的有限元模型。在模态分析的基础上,结合ADAMS建立了曲轴运动机构的刚柔耦合多体系统动力学模型,得到了关键零部件的运动及载荷变化规律,为进一步深入研究曲轴运动系统动态响应奠定了基础,并为整机的优化设计提供了依据。     

涡旋压缩机曲轴及曲轴部件的有限元分析

根据油润滑涡旋压缩机的动力学特性,建立曲轴及曲轴部件两种机构的物理模型和有限元模型。利用ANSYS Workbench有限元分析软件对涡旋压缩机曲轴及曲轴部件的固有特性进行分析,得出前六阶固有频率及各阶振型。分析比较两种情况下固有频率和振型的差异,为曲轴的优化设计与涡旋压缩机的振动分析提供相关依据。     

新型内摆线内燃机曲轴模态分析

利用有限元模态和试验模态分析方法对新型内摆线内燃机曲轴进行了动态特性研究.在Solidworks中建立了内摆线内燃机曲轴部件的三维模型,采用ANSYS中的Block Lanczos法对其进行模态计算,得到前4阶固有频率和振型.并且利用MISO锤击法对曲轴构件进行了试验模态验证.结果表明:两种方法的结果基本一致,曲轴工作频率远离其固有频率,能有效避开共振区.通过模态分析,验证了有限元模型的正确性,为内摆线内燃机曲轴机构的结构优化提供了参考依据.     

隔膜压缩机曲轴的静力学及动力学分析

曲轴是隔膜压缩机传动机构中最关键的零件,曲轴的使用寿命一定程度上决定了隔膜压缩机的可靠性。为分析曲轴的静力学和动力学特征,采用三维绘图软件Solidworks建立曲轴及曲轴连杆机构的模型,基于APDL和Workbench对曲轴联合仿真分析了曲轴的静力学特性。此外,对曲轴分别进行了自由模态和约束模态分析及对比。最后,对曲轴连杆机构装配体进行刚柔耦合瞬态动力学分析。结果表明:在排气终了,气体力最大时刻,曲轴满足静力学强度要求;曲轴的约束模态的固有频率结果相对于自由模态的较大,最小固有频率远远大于激振频率,避免了共振的产生,且振型多表现为弯曲变形;从曲轴连杆机构动力学分析结果可知,曲轴的最大应力主要分布在4个危险部位,且部位1在曲轴转过各个角度,都是应力最大位置,为设计优化提供参考依据。     

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.