采煤机截割部行星架可靠性设计

为提高采煤机截割部行星架在复杂煤层赋存条件下的工作可靠性,以"MG400/951-WD"型号采煤机为研究对象,基于破煤理论,利用Matlab得到含坚硬夹矸的复杂煤层赋存条件下采煤机螺旋滚筒的冲击载荷,结合刚柔耦合虚拟样机技术建立以截割部行星架为柔性件的采煤机刚柔耦合虚拟样机模型,仿真发现了行星架应力集中区域。基于可靠性灵敏度设计理论、可靠性稳健设计理论和性能退化理论,分析行星架设计变量对渐变可靠性灵敏度的影响,构建行星架多目标优化设计状态函数,利用改进粒子群算法,得到设计变量最优解。结果表明,优化后的行星架最大应力下降56.388%,设计变量灵敏度趋于零,行星架关注区域更加稳健,行星架可靠性得到提高。将刚柔耦合虚拟样机技术与可靠性灵敏度设计理论、可靠性稳健设计理论、性能退化理论和改进粒子群算法相结合,提出一种协同刚柔耦合虚拟样机动态可靠性设计方法,对机械设备传动机构的可靠性分析与设计具有重要工程应用价值。     

新型采煤机截割部行星轮系强度分析

以新型薄煤层采煤机截割部行星轮系为研究对象,依据多体动力学理论,建立了采煤机截割部的刚柔耦合模型,并对其进行动态仿真分析,得到了行星轮系各零件的应力和变形情况。对系统中的薄弱零件太阳轮和行星架进行了结构改进,改进后太阳轮齿面最大啮合应力减小了423.26 MPa;行星架的应力集中现象基本消除,疲劳寿命明显提高至次8.302 2×107。该研究方法可用于大型机械行星轮系的结构设计及优化,有助于及早发现系统中的薄弱环节,降低研发和制造成本。     

基于载荷重构理论下采煤机截割部行星架疲劳寿命分析

为研究采煤机截割部行星架在实际工况下的疲劳寿命情况,通过截割实验得到单个截齿三向力载荷,构建截齿三向力载荷重构函数,采用SOR法对重构函数进行求解,依据滚筒结构参数推演出截割部行星架的负载扭矩。运用Ansys workbench瞬态动力学对采煤机行星架进行动力学分析,并将得到的负载扭矩以时间序列的形式施加在行星架上,并将结果文件导入ncode中进行截割部行星架寿命预测,仿真结果表明:输出轴与侧壁板连接处寿命较小,说明此处几何尺寸变化较大,且存在应力集中现象,应作适当的打磨处理。     

新型薄煤层采煤机截割部建模与仿真研究

基于Pro/E、MATLAB、ANSYS、ADAMS和NSOFT软件构造的协同仿真平台,建立了某煤机公司开发的新型薄煤层采煤机截割部刚柔耦合模型并进行动力学仿真,得到采煤机截割部关键零件的应力应变情况,发现壳体和行星架局部出现较大的动应力,结构优化后其应力分布较为均匀,力学性能得到明显的改善;利用NSOFT对截割部输出轴进行疲劳寿命分析,找到其易发生疲劳损坏的薄弱环节。分析结果为采煤机性能改进和结构优化提供了量化依据,缩短了设计周期,具有较高的实用价值。     

薄煤层采煤机行星机构强度分析

基于刚柔耦合多体系统动力学和疲劳累积损伤理论,通过多软件构造协同仿真平台建立了以行星机构为柔性件的薄煤层采煤机多体模型。通过对模型进行动力学仿真分析发现:截割部行星架主要发生弯曲变形和扭转变形,主应力值均在其材料的许用应力范围之内,强度方面满足要求,可靠性较高;牵引部行星架输出端花键根部与退刀槽连接处受力较大,存在局部应力集中现象。对动力学仿真结果中行星机构关键节点的原始载荷谱进行雨流计数和外推处理后,分析其疲劳寿命,得到了疲劳寿命循环次数和疲劳寿命云图。分析结果为研究复杂条件下结构的动应力分布和疲劳寿命提供了新的方法。     

复杂煤层赋存条件下薄煤层采煤机可靠性分析

以刚柔耦合多体系统动力学理论为基础,建立了采煤机截割部刚柔耦合模型,研究了内齿圈在啮合过程中的动力学行为;根据采煤机在复杂煤层赋存条件工作时滚筒受力情况,基于Matlab编程模拟出滚筒的载荷文件。通过Recur Dyn多体动力学软件进行仿真分析,得到采煤机内齿圈的应力分布及其与行星轮的接触力和接触力矩,与理论值进行比较验证了其正确性;通过疲劳寿命计算,得到了内齿圈齿面的最小疲劳循环次数,对内齿圈疲劳寿命的薄弱区域提出改进方法,延长其使用寿命。在产品设计时对其可靠性进行分析,降低了研发成本,为研究采煤机设备在大范围刚性运动与柔性构件小变形运动时的应力和疲劳寿命情况提供了新的方法。     

基于改进PSO-BP的采煤机截割部行星架疲劳寿命分析及预测

为对采煤机截割部行星架进行疲劳寿命分析及预测,建立采煤机的刚柔耦合模型,研究了行星架的动力学特性,得到了其最大应力值并以此作为输入,利用nSoft得到了行星架的疲劳寿命,利用BP、PSO-BP和改进的PSO-BP对不同工况下的行星架寿命进行预测.研究表明:夹矸坚固性系数为8.4,截深600 mm,转速90 r/min,牵引速度2.5 m/min的工况下,行星架的最大应力为554.781 2 MPa,应力集中区域为花键退刀槽处,疲劳寿命为5.507 2×106;BP、PSO-BP和改进的PSO-BP三种神经网络模型中,预测疲劳寿命最大相对误差分别为4.35％、2.52％和0.90％,迭代次数分别为23、8和6次,改进PSO-BP模型既提高了预测精度,也提高了迭代速度.融合Matlab、Ansys、Adams、nSoft和改进的PSO-BPNN,为工矿装备关键零件的疲劳寿命预测提供了方法.     

采煤机运动参数对截割部行星减速器疲劳寿命的影响分析

采煤机进行截割采煤过程中受到的载荷较大,对采煤机的截割部行星减速器的寿命产生影响,而采煤机的牵引速度及滚筒转速是工作过程中两个重要的运动参数,因此针对牵引速度及滚筒转速对行星减速器疲劳寿命的影响进行仿真分析,并建立了疲劳寿命的变化曲线.依据不同的曲线关系,可以对牵引速度及滚筒转速进行协同控制,从而保证行星减速器的疲劳寿...     

采煤机扭矩轴可靠性分析与优化设计

作为保护采煤机关键零部件的扭矩轴,其性能对采煤机的可靠性与使用寿命有重大影响。建立以扭矩轴、摇臂壳体、截割部行星轴和行星架为模态中性文件的采煤机刚柔耦合虚拟样机模型,结合实际工况,基于项目组开发的"采煤机载荷模拟程序"计算获得了采煤机滚筒的载荷文件,通过Adams仿真得到了扭矩轴的最大剪切应力和扭转位移及时刻。基于神经网络和可靠性灵敏度理论得到了扭矩轴剪切应力与位移对卸荷槽结构参数的灵敏度。以采煤机牵引速度和扭矩轴剪切应力与位移为约束条件,对卸荷槽进行优化设计,结果表明:当采煤机牵引速度大于12.236 7 m/min时,扭矩轴及时断裂,提高了采煤机的可靠性与使用寿命。     

基于神经网络的采煤机截割部可靠性研究

滚筒是采煤机截煤时的主要工作机构,其结构参数及运动参数会直接影响采煤机的工作效率及工作可靠性。基于虚拟样机技术建立了采煤机刚柔耦合模型,通过动力学仿真获得采煤机关键零件等效应力值;仿真不同滚筒转速、牵引速度、滚筒螺旋升角及截线距下截割部摇臂壳体及行星架的等效应力值,获得了滚筒结构、运动参数对采煤机截割部关键零件可靠性的影响趋势;结合神经网络技术,以不同滚筒结构、运动参数下采煤机关键零件的等效应力值作为神经网络训练样本,对螺旋升角优化设计,获得在关键零件应力值最小时的滚筒螺旋升角。该研究为滚筒结构、运动参数的选取提供更为准确的理论依据,具有一定的工程应用价值。     

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...     

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.     

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.     

Application of Feature Extraction through Convolution Neural Networks and SVM Classifier for Robust Grading of Apples

This paper proposes a novel grading method of apples,in an automated grading device that uses convolutional neural networks to extract the size,color,texture,an...     

分布动态载荷识别的抗噪处理

针对正交多项式频域法在用多种响应对矩形薄板进行载荷识别中抗噪性较差的问题,综合运用平均法、矩阵预处理和奇异值截断法等方法对之进行改善,并引入空间映射的思想,将该方法的应用范围拓展为复杂的模型.利用仿真算例,证实了该方法具有较好的抗噪性.     

基于MELTAC-N平台的核电厂安全级DCS环网研究与测试

针对工程实践中环网通讯相关问题的处理缺乏理论基础及国产化安全级DCS平台的开发缺乏成熟经验借鉴问题,对基于MELTAC-N平台核电厂安全级DCS环网的软硬件实现进行了研究。提出了安全级DCS环网双环网冗余设计、光切换开关设计等硬件设计方法,以及以RPR协议为基础,采用全数据收发策略的软件设计方法。在CPR1000安全级DCS平台上对安全级DCS环网的可靠性及实时性进行了评价,并进行了容错能力、响应时间及响应时间稳定性测试验证实验。结果表明,基于MELTAC-N平台安全级DCS环网软硬件设计具有较好的容错能力及响应时间稳定性。     

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...     

End-to-End Multiview Gesture Recognition for Autonomous Car Parking System

The use of hand gestures can be the most intuitive human-machine interaction medium.The early approaches for hand gesture recognition used device-based methods....     

The laboratory simulation of abrasive wear

Abrasive wear has long been recognised as one of the most potentially serious tribological problems facing the operators of many types of plant and machinery; several industrial surveys have indicated that wear by abrasion can be responsible for more than 50% of unscheduled machine and plant stoppages. Locating the operating point of a tribological contact in an appropriate operational ‚map’︁ can provide a useful guide to the likely nature and origins of the surface degradation experienced in use, though care must be exercised in choosing the most suitable parameters for the axes of the plot. Laboratory testing of materials and simulations of machine contacts are carried out for a number of purposes; at one level for the very practical aims of ranking candidate materials or surface hardening treatments in order of their wear resistance, or in an attempt to predict wear lives under field conditions. More fundamentally, tests may be aimed at elucidating the essential physical mechanisms of surface damage and loss, with the longer term aim of building an analytical and predictive model of the wear process itself. In many cases, component surface damage is brought about by the ingress of hard, particulate matter into machine bearing or sealing clearances. These may be running dry although, more usually, a lubricant or service fluid is present at the interface. A number of standardised wear test geometries and procedures have been established for both two- and three-body wear situations, and these are briefly described. Although abrasive wear is often modelled as following an ‚Archard’︁ equation (i.e. a linear increase in material loss with both load and time, and an inverse dependence on specimen hardness) both industrial experience and laboratory tests of particularly lubricated contacts show that this is not always the case: increasing the hardness differential in an abrasively contaminated lubricated pair may not always reduce the rate of damage to the harder surface.     

Limits of topographic measurement by the scanning tunnelling and atomic force microscopes

Parameters describing the topographic character of a surface (height, surface wavelength, slope and curvature) can be derived from equivalent sinusoidal profiles. The response of a surface-measuring instrument may be modelled in terms of instrument parameters such as stylus radius, and scanning range and resolution. The performance of the instrument may then be mapped as a zone in amplitude-wavelength (AW) space to show the sinusoidal profiles it is capable of measuring. In a first-order analysis the STM and AFM are considered as equivalent to contact-stylus instruments with a notional stylus radius equal to the tip radius plus the gap. Comparisons between different instruments and types of instrument are readily made by mapping in AW space. The error arising from convolution of the sinusoidal profile with that of the finite tip may be quantified and plotted as contours in AW space.