基于有限元法的新型汽车门锁中塑料斜齿轮强度仿真分析

为研究某新型汽车门锁中的塑料斜齿轮在工作条件下的轮齿受力情况,运用Abaqus建立了斜齿轮啮合的有限元模型,基于非线性接触算法对塑料斜齿轮的接触过程进行了仿真分析,并得到塑料斜齿轮的接触应力与弯曲应力。运用刘易斯方程及齿轮赫兹应力理论对塑料斜齿轮啮合过程中的许用应力进行了理论计算,并与有限元仿真结果进行对比;结果验证了塑料齿轮的强度满足实际工作的要求,并指出齿轮正常啮合过程中最大接触应力出现在齿轮双齿啮合区间,而最大弯曲应力发生在两齿啮合即将进入三齿啮合位置,此时齿轮容易发生疲劳破坏,提出了提高齿轮轮齿强度的改进方案。研究为塑料齿轮的强度分析提供了理论依据。     

渐开线斜齿圆柱齿轮齿面接触强度分析

斜齿圆柱齿轮在啮合过程中,其啮合接触线的总长度不是定值,而该值将影响啮合过程中轮齿间的线载荷,因此分析了斜齿轮对在一个啮合周期内的接触线总长度的变化规律。目前将斜齿轮转化为当量直齿轮计算齿轮齿面接触强度,无法反映啮合瞬时齿面接触应力分布情况。将啮合接触线两侧的斜齿轮轮齿对看做曲率半径不断变化的圆锥台体,并结合斜齿轮啮合原理、赫兹弹性接触理论,通过解析法计算轮齿对任意啮合时刻的齿面接触强度,并分析了轮齿对一个啮合周期内齿面接触强度的变化规律。通过有限元分析软件,对解析法的计算结果进行了验证。     

斜齿面齿轮齿面接触问题的有限元-线性规划解法

提出了一种基于有限元及线性规划计算斜齿面齿轮齿面接触区域载荷分布及啮合刚度的方法。建立了斜齿面齿轮齿面的数学模型,基于matlab实现其齿面及接触轨迹的可视化;基于有限元思想,并结合线性规划改进的单纯形算法,得到齿面接触区域各点载荷分配;根据接触区域平均变形量和载荷计算了啮合齿对的啮合刚度;计算了接触区域最大压应力,并与Hertz理论的计算结果进行对比,验证该线性规划算法的有效性。     

内啮合斜齿轮高精度三维有限元自动建模方法

为提高内啮合斜齿轮有限元接触分析的建模速度和模型精度,提出了一种齿轮高精度三维有限元模型的自动建模方法。基于齿轮插刀齿廓方程,利用齿廓法线法,得到包括齿根过渡曲线的内、外斜齿轮端面齿廓,建立了内、外齿轮参数化粗网格有限元模型。开发了表层六面体网格剖分方法,自动识别齿面接触带单元,进行分级剖分细化,保证了有限元模型的建模精度和网格密度。进行了齿面接触分析,得到了内啮合斜齿轮的弯曲应力、接触应力、接触印痕、传动误差、时变啮合刚度和载荷分配率。粗细网格有限元模型计算结果对比分析表明,该方法提高了内啮合斜齿轮有限元建模效率和计算精度,缩短了计算时间,为快速准确的齿轮接触分析奠定了基础。     

基于ANSYS的斜齿轮接触动力学分析

对齿轮接触动力学原理进行了研究,基于ANSYS建立了一对斜齿轮的有限元模型,根据接触动力学原理和有限元多点约束技术进行了动态接触分析。通过求解获得了齿轮在啮合过程的接触状态和齿根弯曲应力的变化规律,求出了齿面最大接触应力和齿根最大弯曲应力。结果表明,基于ANSYS的斜齿轮接触动力学模拟可以反应啮合过程中实际的动态响应,为精确计算齿轮的强度和疲劳寿命提供了可靠保证。     

基于ANSYS的斜齿轮接触有限元分析

通过接触问题有限元基本理论的研究,应用大型有限元分析软件ANSYS建立多齿对啮合斜齿轮接触有限元模型,对其进行接触非线性有限元分析。计算结果准确直观,为斜齿轮接触应力分析和强度校核提供了更加快速有效的方法。     

结合有限元法和接触理论的内齿轮副啮合刚度计算方法

提出了一种将有限元方法和接触理论相结合的内啮合齿轮副啮合刚度计算方法。该方法通过齿轮整体和局部有限元模型分离出啮合点宏观变形,利用线接触变形解析公式计算啮合点接触变形,求解非线性啮合平衡方程后得到齿轮副时变啮合刚度和载荷分布。该方法相比一般有限元法具有更高的计算效率和稳定性,同时克服了解析方法难以考虑斜齿轮和不同齿圈结构影响的缺点。最后,分析了内齿圈不同支撑数目和齿圈厚度对啮合刚度的影响。该方法可为内齿轮副强度及动态特性设计提供有效指导。     

斜齿轮啮合传动内部激励研究

齿轮啮合传动的内部激励是引起齿轮振动和噪声的关键因素,以某8挡自动变速器中一对常啮合斜齿轮为研究对象,对其啮合传动过程的内部激励开展全面深入研究,包括齿面接触状态、时变啮合刚度、误差激励和啮合冲击。采用有限元法分析斜齿轮的静态和动态接触过程,得到齿面接触应力的大小及分布;采用接触线长度变化表示时变啮合刚度的理论方法和采用有限元仿真的方法得到斜齿轮传动的时变啮合刚度曲线;采用理论计算和有限元法分析斜齿轮误差激励,包含啮合误差、静态传递误差和动态传递误差;采用有限元法分析啮合冲击,得到齿轮传动过程的齿根应力;采用有限元法计算齿面接触线上应力分布。研究为斜齿轮传动状态的改善提供了基础。     

MC尼龙斜齿轮匀速啮合过程瞬态动力学分析

为了得到MC斜齿轮在啮合过程中的接触线特性并对齿轮承载能力进行判断,应用Solid-Works软件建立MC尼龙斜齿轮的三维几何模型,再利用HyperMesh对其进行精确网格划分,最后导入至ANSYS中建立有限元模型,用瞬态动力学中的full法计算分析斜齿轮的啮合传动过程,获得了MC尼龙斜齿轮啮合过程中齿轮应力分布规律。结果表明,齿轮的最大应力出现在齿根位置,齿轮接触线宽度为1.33mm,接触线倾斜角与齿轮螺旋角大致相等,同时还得到了齿根应力谱,为齿轮疲劳寿命计算提供依据。     

三维螺旋齿廓曲面接触强度计算模型

从三维螺旋齿廓曲面的形成得到接触强度计算模型。介绍改进的有限元齿廓曲面接触强度计算法,包括改进的计算方法、确定产生最大接触应力时啮合位置的方法等。提出计入齿面接触载荷非线性及啮合齿对数发生变化时的斜齿轮三维强度有限元建模方法及程序,给出应用实例。该方法使齿面接触强度计算更接近工况。此方法还可应用于圆柱螺旋齿轮、锥齿轮、蜗轮蜗杆等传动接触强度的计算。     

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.