基于正交试验的钛合金切削仿真和工艺研究

使用有限元分析软件ABAQUS建模,对钛合金零件加工过程进行二维切削仿真,研究钛合金在切削过程中,材料特性和刀具前角、刀具后角、切削速度等工艺参数对切削力和切削温度的影响.然后根据多因素多变量的特点,设计正交试验方案,设置对照实验组进行验证,并通过极差分析和方差分析法进行显著性检验,验证了仿真分析结论的正确性.     

基于ABAQUS的表面微织构刀具切削钛合金仿真研究

利用有限元软件ABAQUS构建钛合金切削过程的二维仿真模型,通过钛合金切削试验验证模型的正确性。对微织构刀具切削钛合金的过程进行仿真,与无微织构刀具切削钛合金的仿真进行对比分析,研究了微织构刀具应力分布、切削力的变化规律以及对等效塑性应变的影响。仿真研究表明,微织构的存在对切削过程中刀具的应力分布有积极的改善作用,可以降低切削力,减少塑性应变。     

基于SPH方法的钛合金切削仿真分析

运用Solid Works、hypermesh和ls-prepost软件建立了切削仿真模型,基于光滑流体动力学方法对Ti6Al4V钛合金切削进行了仿真,对切屑形成过程以及切削力进行了分析。仿真分析结果表明:SPH方法解决了切削仿真过程中的网格畸变造成的无法求解问题,同时,切削仿真锯齿形切屑形貌与试验相一致,验证了SPH方法切削仿真的有效性。从而为进一步研究钛合金切削机理以及优化切削参数提供了理论支持。     

高效加工TC4钛合金的铣削过程数值模拟

目前,难加工材料TC4钛合金在切削过程中存在加工效率低、加工表面质量差和刀具使用寿命低等难题。本文针对提高TC4钛合金的加工效率问题,在高速铣削条件下对立铣刀不同轴向切深侧铣加工TC4钛合金进行仿真研究。利用ABAQUS软件建立三维铣削有限元模型并进行相应仿真试验,获取和分析了不同切削条件下的铣削温度场和铣削力波形,并对比了切屑形态。本研究可为高效铣削TC4钛合金实际加工提供理论依据。     

置氢钛合金高速正交切削切削力的仿真

利用分离式霍普金森压杆(SHPB)实验得到置氢钛合金的流动应力与应变关系,通过数据拟合获得置氢钛合金的Johnson-Cook(J-C)热粘塑性本构模型,应用该模型及有限元分析软件模拟了置氢钛合金切削过程,并进行了相关的验证性切削实验。不同置氢含量钛合金切削力对比显示,置氢工艺改善了钛合金的切削难加工性;高速切削置氢钛合金模拟结果表明,在120m/min切削条件下,置氢能够较大的减小切削力。     

基于Voronoi模型的多晶金属切削有限元分析

基于Voronoi建模原理开发了满足金属材料晶体学拓扑规律的多晶建模算法.在晶体尺寸满足对数正态分布时,采用多边形内角阈值来控制晶体饱满度.结合ABAQUS二次开发技术实现了钛合金多晶切削过程的参数化建模及有限元分析,并通过对比车削试验数据和仿真数据验证了模型的可靠性.仿真结果表明:在材料内部晶界的阻力作用下,较小的晶...     

硬质合金刀具高速车削钛合金的切削性能研究

采用单因素试验法,用未涂层硬质合金刀具和TiAlN涂层硬质合金刀具对Ti-6Al-4V钛合金进行了高速干车削试验,通过对切削过程中切削力、刀具寿命、切削温度以及加工表面粗糙度的分析,得出了两种刀具高速干车削钛合金的切削性能,为钛合金高速切削刀具的设计提供了试验依据。     

基于均匀和正交设计的钛合金高速切削仿真研究

为了减少试验次数、提高效率,通过建立基于JC材料本构模型和绝热剪切失效准则的二维切削仿真模型,运用有限元ABAQUS软件在试验前对钛合金TC4进行高速切削模拟。对比均匀和正交两种设计方法在揭示切削参数对表面粗糙度影响规律中的优缺点,为试验研究优选一种设计方法,同时也揭示仿真中切削速度、进给量和轴向切削深度3个切削参数在高速切削条件下对表面粗糙度的影响规律,为试验加工研究切削参数对表面粗糙度的影响规律奠定基础。     

逆-顺铣方式对钛合金TC4高速切削过程影响的比较研究

本文采用仿真软件模拟了PCBN对TC4钛合金进行高速干式切削过程,研究了逆铣-顺铣对钛合金高速切削过程量的影响规律。结果表明,逆铣时的切屑更易卷曲,相较于顺铣多30%,但不易断屑,易于产生毛刺;与逆铣相比,顺铣时的切削温度较低,利于断屑、刀具寿命及零件表面质量;在主切削力和切削热累积双重作用下,逆铣后期刀具抗弯强度很不利,而逆铣时次切削力方向呈y正向不利于切削过程的平稳性。     

基于ABAQUS的切削钛合金的数值模拟分析

基于ABAQUS仿真软件,模拟了切削加工钛合金TC4(Ti6Al4V)的过程。预测出切屑的形状和剪切角的大小,验证了通过剪切失效和单元删除模型实现切屑分离符合切削理论。     

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.     

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....     

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。     

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.     

ANGULAR DISTORTION ALLOWABLE VALUE AND ASSESS METHOD OF WELD ON COKE TOWER

A graph as the new engineering method for estimate the safety of bulging deformation of coke tower is proposed. Through stresses analysis of circumferential weld of coke tower and comparing the stresses produced by pressure with heat stress of steady state, residual stress, bending stress produced by both itself weight and wind loads, it showed that the stresses produced by pressure on the angle distortion are the main factor of equivalent stress of the combined stress. After comparing four kinds of stress controlling conditions, the relation to stress with depth of angular distortion, grade of curvature of angular distortion and half of region of angular distortion has been inferred. Graph of deformation allowable value of coke tower for different condition by angular distortion and half of region of angular distortion has been plotted. The five steps for its engineering use have been explained. The lighter the grade of curvature is, the larger of bulge allowance, may be, and the bigger of depth of angular distortion may pose too. For the coke tower with a popular structure of Dg 5 400 mm×28 mm, the result by graph is nearly more than the result of two formulas formed by other research, the error is less than 7.0%. But, the graph can be easily applied to different size of angular distortion.