动力减振镗杆结构参数优化

深孔镗削过程中,镗杆不可避免产生振动,影响孔的加工质量,为了提高加工质量,本文针对动力减振镗杆建立力学模型,通过对模型的研究得出减振器的最优参数,应用ADAMS动力学仿真软件和试验验证了理论优化的正确性。通过和普通镗杆对比分析,结果表明动力减振镗杆有效地达到了减振效果。     

减振镗杆稳健性分析及优化

为提高镗杆减振性能的稳健性,建立减振镗杆的二自由度系统动力学模型。运用蒙特卡洛仿真方法系统地分析了减振镗杆不确定性因素对动力放大系数的影响规律。综合考虑参数与变量不确定性,以减小激振频域内的最大动力放大系数的均值和标准差为优化目标,对减振系统进行了稳健设计。遗传算法求解结果和仿真试验表明,优化后的减振镗杆减振性能及其稳健性得到了显著改善。     

减振镗杆装夹位置对减振性能的影响

减振镗杆各个参数如减振块的重量、刀座装夹位置等的变化,对镗杆减振性能影响很大。本文对内藏式减振系统的镗杆进行了动力学仿真;通过实验重点研究了镗杆装夹位置对其减振性能的影响,并确定了最佳装夹位置。     

内置式减振镗杆减振性能分析

为了提高镗孔过程中镗杆的稳定性,基于动态减振理论,对内置式减振镗杆的相关参数进行了优化设计,分析了内置式减振镗杆的动力学模型。采用有限元软件对减振镗杆进行了耦合分析。讨论了减振密度、阻尼系数和支撑刚度等参数对镗杆稳定性的影响规律,获取了减振镗杆最佳稳定参数。分析了减振密度、阻尼系数和支撑刚度等参数的频域特征。结果表明:减振镗杆的1阶频率在320 Hz时,随着减振器密度的增加,减振镗杆刀尖径向最大振幅降低;随着阻尼液的阻尼系数和橡胶的支承刚度增加,镗杆的振幅呈现为先减小后增加的变化趋势,试验和仿真结果为减振镗杆的实际应用提供了理论依据。     

动力减振镗杆结构优化及运动稳定性仿真研究

为了研究动力减振镗刀在减振效果最好、运动稳定性最佳时减振系统的特征及结构参数,以长径比为12的动力减振镗刀为研究对象,在对其进行运动稳定性分析的基础上,采用SIMS方法优化确定了减振系统的特征参数,再利用Matlab优化确定了减振系统结构材料参数;然后利用ADAMS进行了减振镗杆的动力学仿真,分析得到了幅频响应曲线和振动—位移时间曲线;最后通过比较分析不同橡胶等效径向刚度值和阻尼液阻尼值下减振镗杆动力学仿真的幅频响应曲线,验证了减振镗杆优化结果的正确性,为大长径比动力减振镗刀的研制提供指导。     

内置式减振镗杆的试制和减振性能分析

介绍了一款内置阻尼减振器的减振镗杆,阐述其基本设计原理及设计过程。试制减振镗杆并与普通镗杆进行安装状态下的振动试验,采集力锤激励下的镗杆振动信号并求出对应的传递函数图像,得出两种镗杆安装状态的一阶、二阶固有频率,比较减振镗杆相对于普通镗杆的固有频率差异。进行两种镗杆的切削试验,采集镗杆径向的振动信号,比较两种镗杆在相同切削参数下的径向振动波形图,评价该款减振镗杆的减振性能,为该款减振镗杆的设计及仿真结果提供试验数据支撑。     

橡胶参数对镗杆减振性能的影响

减振镗杆的减振主要依靠减振系统.减振系统由橡胶,减振块和阻尼液构成.橡胶的弹性、减振块的质量以及阻尼液的粘度和粘温特性等参数都会影响到镗杆的减振性能.若参数调整不好,就会影响镗杆的减振性能.主要研究了镗杆的橡胶参数对其减振性能的影响.     

数控减振镗杆设计与分析

本文对振动影响进行了分析,并在此基础上对减振镗杆进行了初步的设计,并对镗杆的结构、材料、弹性元件、质量块等重要参数都进行了选择设计,通过ADAMS与ANSYS软件对镗杆进行了联合仿真分析,又进行了实际加工对比。最终得出减振镗杆的优越性,对数控镗杆加工的减振措施有一定的意义。     

双级串联调谐质量阻尼器减振镗杆的设计与性能仿真分析

针对大长径比镗刀杆在加工大型复杂零件的孔及孔系结构中容易产生振动、加工效率低且加工质量不稳定等问题,提出了一种内置双级串联调谐质量阻尼器的新型减振镗杆,建立了减振镗杆的力学等效模型,通过求解和分析减振镗杆的振幅比,确定了减振镗杆最优的阻尼器长度及阻尼比。利用MATLAB/Simulink分别求解减振镗杆和普通镗杆的加速度响应信号,结果表明,减振镗杆的吸振性能显著提高,振动衰减时间大幅缩短。应用Workbench对两种镗杆进行模态分析和谐响应分析,得到固有频率和幅频曲线,发现减振镗杆的振幅远小于普通镗杆。本研究为减振刀具的研制与推广提供了一定的理论参考。     

减振镗杆动态特性的对比实验分析

对进口肯纳减振镗杆和自制减振镗杆进行对比切削实验,分析其抗颤振能力的差别。应用实验模态分析、镗杆材料化学成分对比分析等手段,对两种镗杆的动态特性进行分析,为自制减振镗杆的优化设计提供依据。     

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...     

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.     

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.     

Short-Term Relay Quality Prediction Algorithm Based on Long and Short-Term Memory

The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar...