空冷器管箱接管的应力仿真分析

为帮助生产者避免因应力集中而出现接管断裂的情况,提出了一种基于有限元分析的弹性应力分析方法,对空冷器管箱接管进行强度分析。分析有限元仿真计算的结果,得出最大应力位于管箱接管的连接位置。同时,依据《ASME锅炉压力容器规范》对其进行了应力强度评定,验证了设计的安全性和合理性,并基于分析结果提出改进措施,为相关工程设计提供了参考依据。     

汽车后悬架拖曳臂台架疲劳试验失效分析及其改进

为解决某SUV后悬架拖曳臂台架试验耐久失效故障,首先建立后悬架系统有限元分析模型,根据悬挂系统耐久试验装置及其失效工况,在轮心处沿着纵向施加6 000 N,对其进行强度分析,以此确定应变片测试位置。然后基于胡克定律对测试数据进行处理计算,得到测试点的应力值,与有限元模型进行对标分析,分析结果表明两个应变片测试点的台架试验结果与有限元分析的误差率分别为4.5%和5.1%,因此该有限元模型具有很高的准确性。再基于对标成功的有限元分析模型,约束车身所有自由度,在轮心位置施加以纵向力12 000 N,分析结果表明拖曳臂的最大应力为397.3 MPa,并且其应力集中位置与裂纹源一致。通过在开裂的螺栓孔处焊接大垫片,改进之后拖曳臂的最大应力为313.74 MPa,其较改进之前降低了21.1%。最后基于Miner线性损伤理论和Ncode软件对拖曳臂原始方案和改进方案进行分析,其最大损伤值分别为2.3和0.9,相应的拖曳臂疲劳寿命提高了60.9%,改善效果非常明显,其最大损伤值位置也与失效件裂纹源位置相吻合,并且其改进方案最终顺利通过了悬挂系统的台架耐久试验验证。     

某型无人直升机机身框架断裂分析及优化计算

以某型无人直升机机身框架为研究对象,分析断裂原因,采用三维建模,并应用有限元方法进行分析计算,得出断裂主要由应力集中所造成,与金相分析得出的结论一致。同时,采用增加腹板形式进行优化改进,并进行静态与动态分析。结果表明,应变明显减小,应力分布均匀且没有影响整体动态性能。分析和实际使用表明,框架强度明显提高,应力集中情况得到明显改善。     

某薄板动力减振器振动特性研究

使用SolidWorks建立了某薄板动力减振器三维模型,并在Ansys Workbench中进行了有限元模型应力计算和模态分析。应力计算结果表明,该动力减振器薄板弹簧圆角处应力集中明显,最大应力为892 MPa。模态分析结果表明,动力减振器1阶固有频率为60 Hz,满足减振要求。针对应力集中、容易造成疲劳断裂,提出了改进方案,改进后的薄板弹簧根部应力为445 MPa。此外对新方案进行了谐响应分析,仿真分析表明改进后的动力减振器对60 Hz的振动具有很好减振效果。     

某型侧面起重机结构件应力集中问题分析及改进

根据某型侧面起重机结构应力测试结果可知,某结构件存在局部应力集中问题,结构件局部应力值超出结构件材料的需用应力,需要进行分析及改进。提出改进措施,并结合有限元方法对改进后的侧面起重机进行了受力分析,经过试验测试证明,局部应力集中问题得到了解决。     

高方平筛结构断裂及若干因素影响分析

对高方平筛运转过程中筛箱短横梁的断裂现象及产生断裂的若干影响因素进行研究。以筛体框架和悬吊系统为研究对象,采用有限元方法进行了结构动力学建模和瞬态响应分析。根据有限元分析结果与实验数据的对比,对有限元模型及边界条件进行了修正。计算结果显示,结构中应力响应最大值发生在筛箱短横梁处,与结构实际断裂位置一致。进一步计算并分析了偏重块的质量、转速和偏心距、短横梁矩形截面尺寸与壁厚、水平和垂直压紧力等因素对3个较危险位置最大应力的影响规律,所得结果可为高方平筛结构改进和动态优化设计提供参考。     

采用ANSYS的水泥冷却机篦板有限元分析

应用有限元计算方法,对水泥冷却机篦板建立有限元分析模型,并对其进行热-结构耦合应力分析,结果表明,篦板整体应力水平较高,表面通风孔处出现应力集中,极易发生断裂破坏.为降低篦板综合应力水平,对模型进行适当的结构改进,极大地降低了应力水平,增强了设备可靠性.     

1800HP型泥浆泵泵体有限元仿真分析与结构改进

首先建立了1800HP型泥浆泵泵体三维模型,然后对泥浆泵泵体进行3种工况的有限元静力仿真分析。结果表明,泥浆泵泵体后隔板的连接板附近和连接板焊缝处出现应力集中,且最大应力超出所用材料的屈服极限,不满足设计和工作的要求。根据有限元分析结果对泵体结构进行改进,并对改进后的泥浆泵泵体进行有限元仿真分析,改进后的泥浆泵泵体和焊缝的应力集中情况得到明显改善,泵体的整体强度得到加强,增加了泥浆泵工作的可靠性和稳定性。     

双向斜盘式压缩机活塞有限元应力分析

针对双向斜盘式压缩机活塞的独特结构及实际受力情况,提出了一种活塞受力与应力分析的方法.对于活塞容易发生断裂的中间部位,分析了所承受拉力或压力的变化.采用商用有限元软件,对其中部承受最大压力与最大拉力的时刻进行了应力分析,叙述了造型、网格划分、施加约束及加载的方法,并说明了增加活塞中部过渡圆角可以有效地改善该部位的应力集中.     

框式油压机机身的有限元分析和优化设计

利用大型结构有限元软件ANSYS对10MN可移动压头框式油压机机身进行了刚度强度的计算与分析，研究了其在满载工况下两个特定位置时的应力和变形的分布情况，并据此分析了该机身最大应力与变形的发生位置，为框架式油压机机身结构的优化设计奠定了基础。     

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...     

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。     

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。     

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.     

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。     

基于多目标非支配解提取法的电力系统无功优化

针对传统的电力系统多目标粒子群优化算法采用权重系数法将多目标转化为单目标,从而忽视了各目标函数间的竞争关系这一问题,提出将非支配解提取法运用到电力系统多目标无功优化中,并设定了一套提取规则,以电力系统中的有功网损、电压偏差和电压稳定裕度为目标,使目标在充分竞争的情况下得出Pareto最优解,利用IEEE-14节点系统对多目标非支配解提取法的电力系统无功优化进行了仿真测试。研究结果表明,该算法一次运行可以得出多组非支配解,既有偏向单个目标的解也有兼顾所有目标的解,克服了权重系数法的盲目性和单一性,可使电力决策者根据实际问题选择最优解,具有较好的灵活性与多样性。     

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.     

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%.