共查询到20条相似文献,搜索用时 62 毫秒
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以205/55R16轿车轮胎为研究对象,采用计算流体动力学(Computational Fluid Dynamic,CFD)的方法对轮胎抗滑水性能进行数值模拟,通过将滑水速度仿真值与滑水经验公式计算值进行对比,验证了滑水分析方法的有效性。为提升轮胎的抗滑水性能,借鉴仿生非光滑减阻理论,在花纹沟槽两侧壁布置矩形排布的凹坑非光滑结构,采用响应面分析方法对凹坑的顶部圆直径、凹坑深度、顺流向凹坑间距和展向凹坑间距4个参数进行寻优,并从流场变化角度揭示了凹坑结构减阻机理。在此基础上,将减阻最优的凹坑结构引入到整胎滑水分析模型中,通过与光滑壁面花纹轮胎抗滑水性能的对比发现,凹坑非光滑表面花纹轮胎可通过降低胎面动水压力实现轮胎抗滑水性能的提升。 相似文献
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探讨了将表面非光滑形态结构减阻思想与流场主动控制相结合的车身气动减阻方法。将凹坑型非光滑表面布置在MIRA直背式模型的尾部,并在非光滑形态模型的基础上,在凹坑阵中加装喷射速度可变的涡流发生器来控制模型的尾部气流,改善尾涡结构。通过对光滑、非光滑、非光滑加涡流喷射三种模型的三维流场数值模拟,得到不同尾部形态模型的气流速度、压力以及湍动能等参数,对比不同风速下不同模型气动阻力系数的差异以及不同喷射速度下的减阻效果,分析模型尾部流场参数的变化,阐述了非光滑形态车身气动减阻机理以及涡流喷射扰动效应。研究结果表明:通过对非光滑形态被动减阻与涡流喷射主动减阻的优化组合,能有效地减少不同风速下直背式MIRA模型的气动阻力。 相似文献
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为了降低旋成体在空气运动中的飞行阻力,将生物学的叶序排布理论应用于旋成体的非光滑表面排布设计中,并且应用计算机仿真技术,研究了非光滑表面的凹坑尺寸对减阻的影响。在仿真过程中,分别分析了旋成体表面的凹坑深度和凹坑直径对减阻效果的影响,并阐述了叶序排布凹坑能够减阻的机理。计算机仿真结果表明,适当地选择非光滑表面的凹坑尺寸能够改变凹坑的减阻效果。在本文的试验研究条件下,最大总减阻率达到了1.51%。 相似文献
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采煤机截齿齿体的耐磨性能直接影响截齿的使用寿命。在分析对比了现有的截齿齿体耐磨技术的基础上,通过对仿生学中凹坑形非光滑表面的耐磨机理分析研究,设计出了一种齿体带有凹坑形非光滑表面的截齿齿体结构,并进行了模拟的摩擦磨损试验。通过对16种不同参数凹坑结构的摩擦磨损试验结果研究表明,凹坑形非光滑表面结构的耐磨性相对于光滑表面有显著的提升,并通过正交试验分析了凹坑形仿生非光滑结构各参数对耐磨性的影响。 相似文献
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通过建立凹坑形仿生非光滑表面滑靴副的全水动压润滑模型,采用CFD方法及正交试验法研究工况参数(膜厚、转速)及几何参数(坑形、面积率、深径比)对流体动压润滑性能和水膜承载力的影响规律。研究结果表明:凹坑表面产生的承载效应是其静压和动压分布的综合,其中具有凹坑形仿生非光滑表面的斜盘与滑靴相对运动而引起的动压效应起主要作用;工况参数和几何参数对水膜承载力的影响顺序为转速>膜厚>坑形>深径比>面积率;膜厚30 μm、转速3 000 r/min、面积率20%、深径比0.5的三角柱坑为最优水平组合。该研究结果可为高压海水轴向柱塞泵仿生非光滑表面斜盘的设计提供参考。 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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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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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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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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M. Stedman 《Journal of microscopy》1988,152(3):611-618
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. 相似文献