沟槽对湿式离合器摩擦副啮合性能的影响

对表面开设带一定倾斜角度的窄矩形沟槽湿式离合器摩擦副的啮合过程进行了分析.基于已得到实验验证的理论假设,采用微凸体接触模型的威布尔分布,建立基于平均流量模型及威布尔分布的接触因子的摩擦副研究分析模型;推导出摩擦副的流体润滑控制方程,将复杂的啮合过程映射到一维润滑问题下进行求解.讨论了沟槽深度、数量、倾斜角度对啮合性能的影响,结果表明:渗透层厚度越厚,渗透率越高,啮合时间越短,啮合转矩峰值越大;对于3种类型沟槽,三角形沟槽啮合时间最短,圆弧形次之,梯形沟槽啮合时间最长;沟槽倾斜角度越大,啮合转矩越低,啮合时间越短;而沟槽深度对啮合特性影响不明显.     

表面带沟槽湿式离合器摩擦副啮合过程分析

对表面开有矩形沟槽湿式离合器摩擦副的啮合过程进行了分析。采用微凸体接触模型的威布尔分布,建立基于Patir-Cheng平均流量模型及威布尔分布的接触因子的摩擦副研究分析模型;推导出摩擦副的流体润滑控制方程,将复杂的啮合过程映射到一维润滑问题下进行求解。与实验结果相对照表明:啮合过程中理论计算啮合转矩变化与实际情况相吻合,从而验证了理论分析方法的可靠性。讨论了沟槽宽度对啮合性能的影响,结果表明在沟槽数量一定的情况下,沟槽越宽,啮合时间越长。     

表面几何参数对湿式离合器啮合性能的影响

对表面开设带一定倾斜角度的窄矩形沟槽湿式离合器摩擦副的啮合过程进行了分析.基于已得到实验验证的理论假设,采用微凸体接触模型的威布尔分布,建立基于平均流量模型及威布尔分布的接触因子φ.的摩擦副研究分析模型;推导出摩擦副的流体润滑控制方程,将复杂的啮合过程映射到一维润滑问题下进行求解.讨论了沟槽宽度、数量、不同使用状态对啮合性能的影响,结果表明:渗透层厚度越厚,渗透率越高,啮合时间越短,啮合转矩峰值越大;对于三种类型沟槽,三角形沟槽啮合时间最短,圆弧形次之,梯形沟槽啮合时间最长;跑合阶段较正常磨损阶段而言,啮合转矩较大,而啮合时间较短;沟槽越宽,啮合时间越长.     

纸基摩擦材料的压缩性对湿式离合器啮合特性影响

对主动盘下表面有摩擦材料的湿式离合器的啮合过程进行分析。采用Greenwood-Williamson模型,并考虑惯性影响以及摩擦材料受压变形,建立基于Patir-Cheng平均流量模型的研究模型,推导出摩擦副的润滑控制方程,进行求解并分析摩擦材料压缩性对啮合特性的影响。结果表明:考虑摩擦材料压缩性时,由于摩擦材料受压变形,进入混合润滑阶段所需时间变长,整个过程的实际啮合所需时间比不考虑压缩性要长;湿式离合器摩擦副啮合过程中,随着油膜厚度的减小,微凸体作用逐渐变强,流体压力比不考虑摩擦材料压缩性情况下要大。     

CSP摆剪液压离合器温控管理研究

CSP摆剪液压离合器摩擦副高速滑摩时温度过高会引起摩擦片烧蚀和润滑油炭化,因而需要对离合器的工作状态和冷却润滑流量展开研究。依据摩擦学理论和热平衡理论,建立离合器摩擦副温度场数学模型和油液冷却模型。通过对模型的数值求解,获得了摩擦副在不同啮合时间和啮合次数下的温升特性及不同冷却油量下的冷却特性。结果表明:啮合时间和接合次数增大会导致摩擦副温度显著升高;对偶钢片接触面温度场分布规律与接触应力分布规律一致;对偶钢片啮合面终态温度场分布趋于均匀,但高温点总数增多,温度场整体分布较为不均匀;冷却润滑流量在中低热负荷下对摩擦副温升影响低微,而在高热负荷下对摩擦副温升影响显著,但当流量增大到一定值后,增加流量对温升影响微弱。     

考虑表面粗糙度的湿式离合器啮合过程分析

湿式离合器在实际啮合过程中,离合器摩擦片高速运转,摩擦副接触为2个随机粗糙表面的接触,因此分析离合器啮合过程必须考虑摩擦片惯性及摩擦副表面粗糙度的影响.采用Greenwood-Tripp两粗糙表面接触模型,并考虑惯性的影响,对主动盘下表面有摩擦材料的湿式离合器的啮合过程进行分析,建立基于Patir-Cheng平均流量模型的研究模型,推导出摩擦副的润滑控制方程,并进行求解.理论计算得出的啮合转矩变化与实验结果相吻合,验证了理论分析的正确性.     

粘性调速离合器传动机理与数值计算

本文对液体粘性调速离合器的摩擦副进行了流体润滑分析，由于液体粘性调整离合器在调速范围内，其摩擦副往往工作在流体润滑，混合润滑，边界润滑直到直接接触的工况条件下，且近来工程中广泛采用聚α－烯烃型，聚酯型等合成油作润滑剂，本文采用了幂律型非牛顿流体模型，Patir-Cheng的平均流量模型，GT两粗糙平面接触模型并同时计入油膜的惯性影响，推导了相应的平均雷诺方程，并进行了数值计算与分析。     

液体调速离合器中摩擦副热效应的简化分析

液体粘性调速离合器是利用多个摩擦圆盘间的油膜剪切力来传递动力，并通过改变油膜厚度实行无级调速。由于近来工程中广泛采用聚α-稀烃型，聚酯型等合成油作润滑剂，液体粘性调速离合器在调速范围内，其摩擦副往往工作在流体润滑、混合润滑、边界润滑直到直接接触的工况。基于这些特点，笔者采用了幂律型非牛顿流体模型、Patir—Cheng的平均流量模型、GT两粗糙平面接触模型，并计入油膜的惯性影响，建立了热简化研究模型，对液体粘性调速离合器中的摩擦副进行了流体混合润滑状态下的数值计算与分析。     

液体粘性调速离合器中摩擦副的调速分析

介绍了液体粘性调速离合器中摩擦副的工作机理。在调速范围内 ,液体粘性调速离合器中摩擦副往往在流体润滑、混合润滑、边界润滑直到直接接触的工况条件下工作 ,不同的工况以及负载对液体粘性调速离合器的输出转速和输出转矩有很大的影响。采用表面粗糙度的平均模型 ,以及GT微凸体接触模型 ,对液体粘性调速离合器在调速过程中摩擦副所涉及的工况进行了分析讨论。提出了在稳态条件下 ,输出转速与输出转矩的计算方法。     

直齿轮传动非牛顿流体瞬态弹流润滑研究

综合考虑润滑流体的非牛顿特性以及齿轮传动的瞬态效应，采用Bair-Winer粘塑模型推导了非牛顿流体雷诺方程，建立了非牛顿流体瞬态弹流润滑模型；进行直齿轮传动非牛顿流体弹流润滑数值分析，获得了齿轮传动沿啮合线的油膜压力、油膜形状以及摩擦因数的分布。结果表明：在非牛顿流体工况下，油膜厚度、油膜压力以及轮齿表面摩擦因数均有所降低,因此在齿轮弹流润滑研究中应考虑流体的非牛顿特性的影响。     

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.     

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....     

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。     

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.