四辊方管轧机机架有限元分析与结构改进研究

首先根据现有四辊方管轧机机架尺寸数据建立方管成型机组的三维模型,之后把工厂的生产经验和张力减径理论相结合确定机组各项工艺参数。应用显式动力学分析软件对三架方管轧机轧制过程进行仿真,求得钢管所受最大压力大小及出现的时间、位置,从而结合轧制力计算公式得到各架轧机所受轧制力范围。之后把最大轧制力导入有限元软件,对四辊轧机机架进行有限元分析,得到机架在最大轧制力作用下的应力应变分布规律,从而改进机架的薄弱结构,并把改进结果导入有限元软件中进行对比分析。最终在降低机架等效应力的同时,有效降低了机架的自重,且机架变形量增加很小。从而使机架性能得到改善,同时降低了生产成本。     

微张力减径过程的数值模拟

根据某厂13架微张力减径机的减径工艺,利用ANSYS/LS-DYNA大型有限元软件对无缝钢管的张力减径过程进行模拟仿真,得到了减径过程中管坯的应变场和应力场的分布规律.基于实测算结果,分析了管坯经过各机架时轧制力的变化规律.所得结果与实际生产中管坯的轧制状况是相吻合的,表明了该模型的有效性.该模型可为张力减径在线工艺规程控制和离线生产管理提供有力帮助.     

[成形过程仿真优化与集成计算材料工程]限动芯棒连轧管机轧制过程轧件变形行为及规律仿真

基于ABAQUS有限元软件建立了180 mm限动芯棒连轧管机组钢管连轧过程仿真模型。通过仿真模拟展现了连轧各机架连续轧制过程中轧制区钢管横截面上应力、应变及位移的分布和壁厚形成演变过程,揭示了轧制压力分布和轧辊上总轧制力的变化规律以及轧件温度与轧制区摩擦因数对壁厚与轧制力的影响。使用三次样条插值方法从仿真结果数据中提取钢管壁厚和直径,通过研究对象机组的工业生产实测数据验证了有限元模型的正确性。仿真发现:连轧过程中,金属在纵向上先发生减径变形后发生减壁变形,横向上金属主要从孔顶区流向开口区;前三机架接触压力主要集中在孔顶区,变形量较大,是主变形机架,第四五机架接触压力最大在侧壁区,变形量较小,主要起到精整和归圆作用;随着轧制温度的升高,出口壁厚增大,轧制力减小,随着芯棒与轧件之间摩擦因数的增大,壁厚减小,轧制力减小。仿真研究结果支撑了针对该机组的关键轧机结构参数设计、轧制工艺参数确定以及工程调试中工艺参数优化。     

减(定)径机轧辊机架有限元分析及优化设计

利用Pro/MECHANICA软件,分析了减(定)径机重要部件--轧辊机架在最大轧制力下的应力、变形情况,并根据所得结果,利用灵敏度分析方法对机架进行了优化.通过模拟装配以及对优化前后机架的各项性能指标的比较,验证了优化的合理性和有效性.     

无缝钢管张力减径过程的有限元模型开发及应用

为了研究热轧无缝钢管张力减径过程的金属变形,利用组元建模原理,把张力作为相邻机架之间的边界条件,使得张力减径过程分为机架上的轧制变形过程和机架之间的网格再生过程。建立高阶拟合函数来精确描述轧辊孔型曲面,应用摩擦元模型来模拟接触摩擦,并用正割模量法来求解非线性方程组,在上述理论基础上开发张力减径弹塑性有限元模型,利用该模型对某厂张力减径机组进行有限元建模分析。通过与实际轧制结果比较可知,模拟计算与实际轧制的产品断面形状接近,都呈现轻微内六方形状,且壁厚变化规律一致,几何尺寸与实测值吻合良好,表明所开发的钢管张力减径弹塑性有限元模型能够满足工程计算要求,为预测断面形状和终轧尺寸精度提供有效研究手段。     

D56G90冷辗环机机架的三维有限元分析

根据机床的实际情况,简化了有限元分析的实体模型,建立了机架力学模型,应用三维有限元方法对其进行应力应变分析,找到了机床的薄弱部位―拉杆,得到了一些规律性结论,在65KN轧制力作用下机架伸长率为0.01%。通过与理论分析结果和实际情况的比较发现,模拟分析的结果符合实际,分析结论对设计过程有指导作用。对带预应力装配结构的有限元分析问题有借鉴作用。     

轧钢机机架有限元分析及优化设计

根据某1700粗轧机结构设计方案,使用有限元分析软件COSMOSWorks,建立了结构分析模型.通过对模型的计算分析,得出了该机架承受最大轧制力时最大应力所在位置和应力分布规律.根据分析结果,对其进行优化设计.最后对其进行强度和刚度校核,验证其满足使用要求.     

微张力减径过程热力耦合有限元模拟

根据某厂十机架微张力减径机组轧制工艺,采用大变形弹塑性有限元法建立了管坯连轧三维热力耦合计算模型,并对实际工艺过程进行数值计算,得到了连轧过程中轧件的温度场、应变场和应力场分布规律。基于计算结果,分析了管坯壁厚分布规律、机架力能参数分布。所得结果与现场设定、实测结果吻合良好,表明了该计算模型的有效性。该模型可为现场张力减径工艺过程离线分析提供有力帮助。     

基于有限元的三辊行星轧制力模拟

采用有限元技术对三辊行星轧制力进行了模拟计算,论述了TP2铜管坯三辊行星轧制过程有限元模拟的关键技术与实现方法,建立了有限元计算模型,获得了轧制力的变化规律.研究表明:三辊行星轧制过程中,轧制力在坯料的周向方向呈120°分布变化,在轧制过程中坯料的形状、坯料与轧辊的接触部位时刻发生变化,轧制力呈现波动现象.     

基于ANSYS Workbench的自走式山地微型水稻联合收割机结构的有限元分析

基于Solidworks软件平台建立自走式山地微型水稻联合收割机机架结构的几何模型,应用有限元分析软件ANSYS Workbench对机架结构进行有限元分析,得出机架结构在承受负载作用时的整体位移和应力分布状态,获取机架应力出现最大值的位置,并用强度校核理论对机架结构的应力分析结果进行了校核,结果表明机架结构的设计符合强度要求。机架某些部位的强度富裕,尚有优化空间。有限元分析结果可为今后机架结构或材料的改进提供参考理论依据。     

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...     

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.