柴油机机体与油底壳组合瞬态响应有限元分析

采用ANSYS有限元分析软件建立了495型柴油机机体和油底壳组合的有限元模型,对机体施加缸内压力,活塞侧向力以及主轴承力,并进行了有限元瞬态响应计算,得出机体的一个工作循环的表面振动速度响应,结果发现在机体曲轴箱中部对应于第三、第四轴承处振动最大,计算结果为改进机体结构、降低振动噪声提供了依据。     

四缸柴油机机体结构强度及缸套变形分析

以某四缸柴油机机体组合件为对象,对机体、气缸盖、气缸套、油底壳等多个零件、部件的组合件进行了全面的有限元分析和结构改进.在机体组合件强度分析的基础上,深入阐述了截面圆度、漏光率、圆柱度、同轴度、连续13个截面最小半径等气缸套变形评价指标的意义.并且运用这些指标对原方案及改进方案进行分析比较,得出以下结论:改进方案降低了原方案中偏高的机体隔板应力,降幅达32%已处于安全水平;改善了气缸套的变形,可以有效地提高发动机排放性能.     

基于多体动力学的柴油机机体振动分析

以降低某柴油机振动为目标对柴油机机体进行结构改进,并对改进后的机体进行振动分析.使用HyperMesh软件生成机体和曲轴的高质量有限元模型,结合ANSYS软件进行机体模态分析并制作曲轴柔性体文件;在ADAMS软件中建立曲轴连杆机构刚柔耦合模型,求解作用于机体的动态载荷;在ANSYS Workbench软件中进行机体瞬态...     

柴油机机体-主轴承盖接触面有限元分析

针对某V6大功率柴油机机体在与主轴承盖接触的部位产生疲劳裂纹的现象,运用Pro/E特征建模技术建立起三维实体模型,然后利用ANSA进行有限元模型建立,最后利用ANSYS对其在预紧和爆发两种工况下的应力、变形和选定接触面上摩擦力的分布情况进行了分析计算,预测了机体接触面上的危险位置并与实际情况进行了对比。验证了模型的精确程度,为寻找机体结构强度薄弱区域提供了参考方法,为机体结构的改进提供了理论依据。     

发动机机体的模态分析与减振研究

利用ANSYS软件的模态分析功能,对465Q汽油机的机体在建立底部被约束的机体三维实体模型的基础上,对机体结构进行了约束模态的有限元分析.得到了机体结构的前10阶固有频率及相应振型.从中可看出机体各部分振动的大小,据此对机体结构提出了一些合理改进的建议.     

柴油机体结构有限元模态分析和模态测试

为了解决某科研项目问题,需要利用有限元分析软件ANSYS对某柴油发动机机体结构建立有限元模型,并进行自由模态分析计算,从而得到该机体结构的低阶振动模态频率与模态振型。在得到有限元模型后需要对该机体结构进行模态试验测试加以对比验证。通过有限元模态分析与模态测试结果的对比,验证了有限元模态分析模型与结果的合理性,为该类型发动机机体结构设计与优化提供了参考依据。     

提高柴油机机体刚度的试验模态研究

利用试验模态方法,对494柴油机进行了机体的模态试验和分析,得到反应机体动态特性的振型以及固有频率。通过封闭机体前端主轴承孔上方的孔,改变孔的形状;增加孔周围的壁厚同时改变机体排气侧加强筋的布置与尺寸的方法,对机体进行了结构修改,优化了机体结构,并对改进后的机体又进行了试验模态分析。结果表明:优化后的机体结构在分析频段(0～2000)Hz范围内的振型由原来的十一阶变为九阶,且中低阶模态频率有明显的上升,改进后的机体刚度有了提高,机体结构的动态特性有了改善。     

柴油机缸盖螺栓的三维有限元分析

结合大功率柴油机性能强化的数值计算，在考虑螺纹的基础上建立了气缸盖螺栓的CAD装配体模型；并采用接触分析法对螺栓的应力应变进行了三维有限元计算，对螺栓的疲劳强度进行了校核。分析结果表明，螺纹受力仍处于弹性变化范围，可采用转角法进一步拧紧。     

工程用钻杆螺纹断裂失效研究

工程用坑道钻机钻杆在孔内受各种载荷作用,包括弯曲、扭转、振动及拉压等,钻进时经常出现钻杆断裂现象,严重影响正常生产.从钻杆接头连接螺纹失效类型分析入手,考虑实际工作载荷对钻杆联结螺纹进行力学分析.基于有限单元法,建立了钻杆连接螺纹接触有限元模型,针对Φ42钻杆进行了强度分析,并对钻杆材质进行了断口的形貌、化学成分测量、硬度测量、金相分析,得出钻杆接头螺纹应力偏高,热处理工艺不稳定为钻杆断裂失效的主要原因,研究为进一步优化钻杆结构提供了重要依据,具有重要的理论意义及工程应用价值.     

偏心弯矩对高压流变仪立柱螺纹根部应力的影响分析

为了精确分析高压流变仪立柱螺纹根部的应力特性,运用ANSYS子模型技术,建立流变仪机架整体模型和立柱螺纹联接精确局部模型,分析了立柱螺纹承受偏心载荷情况下的根部应力特性.分析表明机架变形产生的偏心弯矩对立柱螺纹根部应力沿圆周方向的分布影响显著,并给出了降低根部应力集中的有效途径.论文提出了子模型技术在复杂边界条件下进行螺纹精确分析时的应用方法.     

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.     

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.