基于ABAQUS的滚滑轴承模态分析

借助ABAQUS有限元软件对滚滑轴承进行模态分析。验证了轴承内圈固有频率和振型的有限元模型计算结果与理论公式计算结果一致性较高,对比分析了3种类型的滚滑轴承在相同边界条件和载荷作用下的基频、一阶和二阶径向振动弯曲模态,为有限元方法求解轴承以及其他结构模态特性和优化结构动力学性能提供基础。     

气动旋扣钳主件动刚度研究

动刚度是指结构在特定的动态激扰下抵抗变形的能力.旋扣钳作为石油钻井平台井口关键设备之一,研究其动刚度,以提高其动力学性能.对气动旋扣钳的主件进行了动刚度研究,通过锤击法来测量气动旋扣钳主件的结构动刚度,得到了气动旋扣钳主件的动刚度曲线.由动刚度曲线得到的前四阶固有频率,与用有限元法模拟计算的前四阶固有频率吻合,误差小于10％.分析动刚度曲线,表明动刚度随频率的变化而变化,激振频率等于固有频率时动刚度最小.研究成果为进一步提高气动旋扣钳的动力学性能提供理论依据.     

陶瓷球滚动疲劳试验机驱动轴的模态分析

随着陶瓷球滚动疲劳试验机转速的提高,产生的振动问题越来越严重,为了优化试验机的动力学性能,对其驱动轴进行模态分析。先简化驱动轴,得出驱动轴的振动力学模型,用理论方法解出第一阶横向弯曲固有频率为787.4266Hz,再使用Ansys软件对驱动轴进行模态分析,得出驱动轴的各阶模态,其中一阶横向弯曲固有频率为779Hz,理论和软件计算的结果误差只有1.08%,证明Ansys软件对驱动轴模态计算的准确性,其结果可以为试验机动力学性能的优化提供了依据。     

双螺杆泵螺杆在不同约束下的模态分析比较

为了避免双螺杆泵在周期性变化的流体作用下发生共振,优化双螺杆泵的力学性能,对其螺杆转子进行模态分析。先简化螺杆,得出螺杆的振动力学模型,用理论方法解出其第1阶固有频率为525.183 5 Hz,再使用ANSYS软件对螺杆转子进行不同约束情况下的模态分析,得出螺杆转子的各阶模态,其中螺杆转子在弹簧阻尼约束下分析得到的第1阶固有频率为526.4 Hz,理论和软件计算的结果误差只有0.23%,证明使用弹簧阻尼约束模型对螺杆转子模态计算更接近实际情况,可以应用此结果作为双螺杆泵动力学性能优化的依据。     

有限元分析在磁头悬架动态特性研究中的应用

使用有限元分析软件ANSYS对磁头驱动机构的悬架进行了模态分析和计算,得到了悬架的固有频率和特征振型;利用瞬态动力学分析,得出了悬架的动力学瞬态响应;验证了有限元分析软件分析计算的准确性,为悬架的振动敏感性和结构优化研究提供了理论基础.     

基于振动噪声的柴油机油底壳结构优化研究

基于模态参数的动态特性,针对某型柴油机振动噪声超标问题,利用有限元软件ABAQUS的模态分析功能对主要噪声源油底壳的自由模态进行计算,从固有频率方面着手优化其结构。优化后的其固有频率大幅提高,经整机振动噪声测试,减振降噪效果明显,解决了振动噪声超标问题。     

国家低频振动基准装置动圈模态优化

动圈是国家低频振动基准装置的核心部件,其设计质量的优劣直接影响振动装置的性能。使用理论公式和有限元方法对动圈进行固有频率计算,分析其各阶模态;提出针对性措施以利于动圈模态优化,实现提高振动基准装置性能的目的。     

硬齿面滚剃刀的参数化建模及振动特性分析

介绍了基于Pro/E的硬齿面滚剃刀参数化建模方法,运用ANSYS软件对滚剃刀的振动特性进行了有限元分析,计算出了滚剃刀的固有频率和振型,以避免共振的发生,提高硬齿面的加工精度。同时也为滚剃刀的结构优化设计和进一步的动力学分析提供了理论依据。     

功能振动载荷作用下民机发动机区域液压管路动力学响应研究

民机发动机正常工作时产生的功能振动载荷严重影响了该区域液压管路的安全性能和使用寿命,是民机液压管路设计重点考虑问题之一。针对ARJ21-700民机发动机区域某根液压管路,对其进行功能振动载荷作用下的动力学响应分析。基于传递矩阵法,建立液压管路动力学数学模型;采用ABAQUS有限元软件建立液压管路有限元模型,对其进行模态分析和在功能振动载荷作用下的振动响应分析,得到管路固有频率和应力响应规律;对管路危险部位疲劳寿命进行预估。最后,通过理论计算、仿真分析和试验,验证了液压管路动力学数学模型和有限元模型的正确性,研究结果为民机发动机区域液压管路设计及优化提供了理论参考。     

基于有限元法的试验机转轴动力学分析

试验机转轴的动态特性极大地影响了试验机的动力学性能和工作精度,论文利用有限元方法(FEM)对试验机转轴进行了模态分析和谐响应分析,利用模态分析得出转轴的各阶模态及其固有频率,利用谐响应分析得出对转轴振动影响最大的模态。模态分析结果说明固有频率的大小与模态发生的部位有关,同一部位发生的模态固有频率接近;谐响应分析结果说明转轴左端前后方向和竖直方向的弯曲振动模态比较容易引起转轴的共振。分析结果为转轴结构的进一步优化提供了理论参考。     

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...     

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...     

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。     

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。     

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.     

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.     

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.