基于模态预测及敏度分析的机床动特性设计方法

为了提高机床的动态性能,以机床整机固有频率和频响函数振幅为目标,提出基于机床测试数据、进行试验模态分析及灵敏度计算的机床动态特性设计方法。方法首先提取机床测试数据建立机床结构原型模型,逐步计算机床大件结构和整机的固有频率对刚度、质量的灵敏度,确定结构薄弱环节;继而,对薄弱结构,采用模态预测和灵敏度分析方法设计计算,获取更合理的质量和刚度;之后,将设计分析结果输入LMS_Test.lab软件,借助软件完成对原型结构的模态修改,对修改后结构的动力学特性进行模态预测;最后,进行预测结果模态置信验证,确认模态预测的正确性,完整机床动态特性设计方法体系。将该方法应用于实际机床设计中,对比整机优化前后的频响函数曲线和仿真分析验证均证明,基于模态预测及灵敏度分析的机床动态特性设计方法完成的机床优化设计使得机床固有频率得到提高的同时振幅下降,机床的大件结构及整机的动态性能均有提升。     

基于模态试验的高精度磨床动态特性研究

高精度数控复合磨床是近年来国内逐渐推广的新型精密磨削加工设备。高精度指标对磨床动态特性提出了更高的要求。对高精度数控立式复合磨床MGK28120进行了试验模态分析,得到其前几阶模态的模态参数,通过对模态频率、模态振型的分析,找到了该高精度立式复合磨床结构的薄弱环节以及其第一阶模态频率较低的原因。针对薄弱环节提出了相应的修改建议,为该高精度磨床结构优化设计和整机动态特性的提高指明了方向,为其加工效率的提高做了必要的理论准备。     

低速汽车整车模态试验研究

针对某新开发的农用运输车的整车振动情况,对该车的动态特性进行分析研究,通过进行模态试验,获取其固有频率、模态振型等模态参数,分析其动态特性方面可能存在的缺陷,为进一步的改进设计提供试验依据.     

SGM50A立滑板动态特性分析

SGM50A立滑板是该机床主要支撑件之一,其动态特性直接影响着机床的加工精度,对其进行动态特性分析有着重大意义。用ANSYS软件对立滑板进行了自由模态和约束模态分析,分别将有限元计算结果和立滑板自由模态试验及约束模态试验结果进行对比,识别出了立滑板薄弱环节,为立滑板的结构优化设计提供了理论指导。由立滑板的侧面模态试验分析得出,立滑板在安装后出现了上下两端受力不均现象,并提出了装配上的改进措施。     

火箭仪器舱试验与计算模态相关性分析

针对火箭仪器舱,研究了计算模态和试验模态的相关性分析问题。首先介绍模态相关性分析的一般方法。针对仪器舱结构复杂和模态密集的特点,引入整体模态和局部模态的概念,并提出一种用模态应变能比值区分整体模态和局部模态的定量的方法。进而研究了模态向量减缩、误差定位和模型修改等问题。在此基础上,得到了较高的试验和计算模态相关性结果,验证了计算模型,并为进一步的仪器舱减振设计提供了依据。     

减振镗杆动力学特性研究

针对进口与自制减振镗杆,基于模态试验,分析其动力学特性。实践结果表明,模态试验分析是深入了解减振镗杆在工作状态下动态特性的有效手段,所获得的数据可为自制镗杆的设计改进与结构优化提供支持,分析结果也可为设计相类似的减振镗杆提供参考。     

模态试验架的动态特性研究

采用有限元技术，应用ANSYS仿真软件分析模态试验架的动态响应。通过建立计算模型，施加边界约束对模态试验架进行模态计算，得到模态试验架前5阶固有频率，提取计算模型的节点位移值形成模态振型。通过对模态试验架动态特性的研究为模态试验架的设计和导弹模态试验的实施提供参考依据。     

模态试验架的动态特性研究

采用有限元技术,应用ANSYS仿真软件分析模态试验架的动态响应.通过建立计算模型,施加边界约束对模态试验架进行模态计算,得到模态试验架前5阶固有频率,提取计算模型的节点位移值形成模态振型.通过时模态试验架动态特性的研究为模态试验架的设计和导弹模态试验的实施提供参考依据.     

ZH1105WG型单缸柴油机缸体动态特性分析

缸体是柴油机的主体结构，掌握其动态特性对于了解整机的特性非常重要。本文用谱均衡瞬态随机激励技术对ＺＨ１１０５ＷＧ型单缸柴油机缸体进行了实验模态测试，获得了缸体的模态参数，同时运用有限元方法对该柴油机缸体进行了动态特性计算，计算结果和试验分析结果相符性很好，从而为缸体进行结构修改提供了可靠的依据。     

某高射机枪的有限元和实验模态分析

为进一步研究高射机枪的动态特性,特对该机枪自动机进行了实验模态分析,获得了其固有频率、阻尼比和振型。以UG软件为基础进行了有限元模态分析,并与试验的结果进行了对比和验证。通过实验模态和计算模态的对比,验证有限元模型具有较高精度的动态响应特性;为后续的动态设计优化提供理论依据。     

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。     

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...     

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.     

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。     

RLS and LMS blind adaptive multi-user detection method and comparison in acoustic communication

RLS and LMS blind adaptive multi-user detection algorithm and multi-user detector was proposed to solve the problem of multi-user signal detection problem encountered in underwater acoustic communication networks.In simulation analysis,RLS and the LMS blind adaptive multi-user detector were designed and tested for synchronous and asynchronous multi-user communication process.The results of SIR comparison and MMSE comparison show that,both of the two methods can realize blind adaptive detection when any user change in multi-user communication,during this process,the training communication sequences are not needed.The RLS algorithm has about 5 dB higher in SIR compared with LMS algorithm,and the convergence velocity of RLS algorithm is also higher than LMS algorithm when the communication users change.RLS algorithm has better ability in multi-user detection than that of LMS algorithm,and it has great attraction and guiding significance for solving the problem of multiple access interference(MAI) in multi-user communication.     

Robust Impedance Control of Robots Using an Adaptive Interaction Force Observer

For robot interaction control,the interaction force between the robot and the manipulated object or environment should be monitored.Impedance control is a type ...     

Research on key techniques of expendable conductivity temperature depth measuring system

This paper analysis the developing of expendable conductivity temperature depth measuring system(XCTD)and introduce its principle of measuring about temperature,salinity and depth of ocean.Some key techniques are put forward.According to the real needs of XCTD,conductivity sensor with high sensitivity is designed by principle of electromagnetic induce,the ocean conductivity from induced electromotive force has been calculated.Adding temperature correction circuit would help to reduce error of conductivity measurement because of sharply changing temperature.Advanced temperature measuring circuit of high precision and the constant current source is used to weaken effect of self-heating of resistance and fluctuation of the source.On respect of remote data transmission,LVDS is a good choice for the purpose of guarantee the quality of data transmitted and the transmission distance is reaching to thousand meters in the seawater.Modular programming method is also brought into this research aimed at improve the stability,reliability and maintainability of the whole measuring system.In February,2015,the trials in South China Sea demonstrate that the developed XCTD realize effective measurement at a speed of 6 knots and detection depth at 800 m.The consistency coefficient of the acquired data is greater than 0.99 and the success rate of probe launching is above 90%.     

CHARACTERISTCS OF FLUID FILM IN OPTIMIZED SPIRAL GROOVE MECHANICAL SEAL

In order to investigate the sealing performance variation resulted from the thermal deformation of the end faces, the equations to calculate the fluid film pressure distribution, the bearing force and the leakage rate are derived, for the fluid film both in parallel gap and in wedgy gap. The geometrical parameters of the sealing members are optimized by means of heat transfer analysis and complex method. The analysis results indicate that the shallow spiral grooves can generate hydrodynamic pressure while the rotating ring rotates and the bearing force of the fluid film in spiral groove end faces is much larger than that in the flat end faces. The deformation increases the bearing force of the fluid film in flat end faces, but it decreases the hydrodynamic pressure of the fluid film in spiral groove end faces. The gap dimensions which determine the characteristics of the fluid film is obtained by coupling analysis of the frictional heat and the thermal deformation in consideration of the equilibrium condition of the bearing force and the closing force. For different gap dimensions, the relationship between the closing force and the leakage rate is also investigated, based on which the leakage rate can be controlled by adjusting the closing force.