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借助刚塑性有限元软件DEFORM-3D针对4Cr9Si2马氏体耐热钢楔横轧成形过程进行有限元数值模拟,得到楔横轧工艺参数——楔尖圆角对楔横轧4Cr9Si2马氏体耐热钢轧件对称中心的心部缺陷以及轧件表面的表面螺旋痕和对称中心横截面拉细的影响规律:随着楔尖圆角的增大,轧件表面径向力的数值得到减小,从而使横楔轧轧件表面螺旋痕将会明显减小;当楔尖圆角增大后,轧件心部横向应力σy和切应力τxy的持续时间将增加,同时,楔横轧轧件心部第一主应力σ1的方向将会发生改变,使轧件心部金属朝横向y方向流动,从而增加了楔横轧轧件心部缺陷产生的可能性;楔尖圆角增大,轧件轴向力Fz的数值将会减少,从而能够改善对称中心横截面拉细状况。进行4Cr9Si2马氏体钢的楔横轧轧制试验,验证有限元模拟结果的可靠性,并通过增大展宽角获得合格的轧件。 相似文献
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板式楔横轧接触区表面应力分布规律研究 总被引:1,自引:0,他引:1
楔横轧接触表面是形状复杂的空间曲面,接触表面应力分布变化规律相当复杂,对于其认识程度至今还局限于作较多假设的滑移线法分析结果,致使在模具设计和实际生产上主要依靠经验因素,阻碍楔横轧的应用和理论的发展。根据板式楔横轧的特点,在有限元ANSYS/DYNA软件基础上进行二次开发,编制模拟板式楔横轧轧制过程的命令流程序,模拟其轧制过程,获得接触区空间曲面形状,并较详细分析在楔横轧展宽段接触区的空间接触曲面上轧件接触表面应力的分布变化规律。研究结果为避免轧件表面产生缺陷、指导楔横轧模具设计和确定轧机力能参数等提供重要的理论依据。 相似文献
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工艺参数对多楔轧件接口质量的影响规律 总被引:3,自引:1,他引:2
楔横轧多楔成形工艺是生产长轴类零件的先进方法,但生产过程中模具工艺参数对轧件接口质量的影响比较复杂。根据楔横轧多楔模具的工艺特点,建立多楔轧制长轴类零件的三维有限元模型。基于ANSYS/LS-DYNA有限元模拟软件,在不同模具工艺参数下对多楔轧制过程进行了有限元模拟,得到模具工艺参数对轧件接口质量的影响规律。在与模拟工艺参数相同的条件下进行轧制试验,试验结果和模拟结果一致。通过对理论模拟和轧制试验获得结果的分析,得到工艺参数中过渡角对轧件的接口质量影响最大、展宽角对轧件接口质量影响最小的结论。综合考虑各工艺参数的影响,给出保证轧件接口质量良好的过渡角选择范围。研究结果为多楔成形长轴类零件的模具设计提供理论依据和参考。 相似文献
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Clarence W.DE SILVA 《Instrumentation》2019,(4):72-84
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... 相似文献
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INTEGRAL EQUATION METHOD'S APPLICATION IN HOLE-EDGE STRESS OF COMPOSITE MATERIAL PLATE WITH DIFFERENT SHAPED HOLES 总被引:1,自引:0,他引:1
LI Cheng ZHENG Yanping 《机械工程学报(英文版)》2008,21(6):115-118
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. 相似文献
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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. 相似文献
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The fraction defective of semi-finished products is predicted to optimize the process of relay production lines, by which production quality and productivity ar... 相似文献
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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.... 相似文献
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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... 相似文献
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分布动态载荷识别的抗噪处理 总被引:2,自引:2,他引:0
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. 相似文献
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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。 相似文献
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J. A. Williams 《Lubrication Science》1997,3(3):267-306
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. 相似文献
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CHEN Sunyi 《机械工程学报(英文版)》2007,20(6):13-17
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. 相似文献