应用灵敏度分析的TY型自卸车车架结构优化设计

运用Hypermesh软件建立了TY型自卸车主副一体式车架的有限元模型,通过稳态力学分析发现该车架存在构件各部位所受应力严重不均衡的现象,并对车架结构进行了优化设计。通过对弯扭工况下车架构件的柔度系数灵敏度和质量灵敏度的计算,并基于灵敏度分析的结果确定优化设计变量,以车架的总质量最小作为优化目标,以车架的强度和刚度作为约束条件进行优化。优化结果表明:在满足车架整体性能要求的前提下,优化后的车架最大应力值明显减小,避免了应力集中现象,并且车架质量减轻了82kg,验证了该优化设计方法的有效性。     

基于灵敏度分析的主起落架前摇臂寿命优化

某型飞机主起落架车架前摇臂是决定主起落架翻修寿命的关键结构,在使用过程中多次出现疲劳裂纹,采用CAE对结构进行疲劳分析,分析结果显示结构疲劳寿命过低。据此提出基于疲劳寿命的改进优化,采用灵敏度分析方法,来确定各相关参量的敏感程度,找出主要的影响尺寸变量,并利用多目标优化找出最佳尺寸,依据优化结果建立模型对比分析。结果表明,在结构质量几乎不变的情况下,应力集中得到明显改善,疲劳寿命提高了49.7%,有效改善了前摇臂的疲劳寿命。     

基于PSD法的电动轮自卸车车架随机振动疲劳寿命预测

针对国产首台载重达300 t的电动轮自卸车车架疲劳性能是否满足设计要求而开展数值分析研究,拟通过寿命预测评估车架疲劳可靠性。首先在MSC.Nastran中对车架进行模态和频率响应分析,获得模态中性文件和输入与结构应力之间的传递函数;再次,借助ADAMS建立整车刚柔耦合多体动力学模型,进行整车C级路面动力学仿真分析,输出车架随机载荷时间历程,并通过傅里叶变换计算其功率谱密度函数(PSD);最后,根据车架材料SN曲线,利用MSC.Fatigue中的Vibration模块进行振动疲劳寿命分析,得到车架危险点的寿命值满足设计要求,从而为后续开展车架可靠性设计和结构优化提供参考依据。     

边梁式车架的结构灵敏度分析及设计优化

建立了某边梁式车架的有限元模型,利用MSC.NASTRAN分析计算了其弯曲刚度和扭转刚度,并对车架弯曲刚度和扭转刚度进行相对于主要零件板厚的灵敏度分析,以此灵敏度分析结果为依据对车架进行轻量化设计。为该类型边梁式车架结构灵敏度分析和设计优化提供方法和理论依据。     

紧急转弯对客车车架疲劳耐久性的影响研究

对客车紧急转弯工况进行抽象简化,并作为客车车架有限元计算模型的输入,求得了该行驶工况下客车车架的应力和位移场分布,且进一步统计了其应力分布比重;在此基础上,借助Fe-safe软件,采用平均应力修正的Brown-Miller法,对客车车架进行疲劳耐久性计算,得出其疲劳寿命及疲劳裂纹发生位置,为其设计和分析提供了方法和理论支撑。     

基于相对灵敏度分析的自卸车车架轻量化设计

在Hypermesh中建立TY型自卸车车架有限元模型,对车架进行了弯曲和扭转工况下的强度与刚度分析,并通过模态试验验证了有限元模型的准确性。对车架部件进行柔度灵敏度、模态灵敏度和质量灵敏度的计算,基于相对灵敏度分析的结果确定优化设计变量,在保证车架刚度和低阶模态频率的前提下,对车架结构进行轻量化优化。结果表明:优化后车架的强度、刚度和低阶模态频率均有所提高,避免了应力集中现象,车架质量减少70 kg,验证了该轻量化设计方法的可行性。     

某车架结构基于灵敏度分析的优化设计

建立了某自卸车车架有限元模型,通过模态试验和模态有限元分析得出了车架固有频率,并且验证了该模型的准确性和合理性。依据车架结构的灵敏度分析结果来选择设计变量,在保证车架低阶模态频率和强度的前提下,以车架轻量化为目标优化车架构件厚度,实现了车架质量8.0%的降低幅度;在控制车架质量和强度的条件下,以提高车架低阶模态频率为目标,实现了车架结构的低阶模态频率和动态性能的提高。     

汽车车架结构的拓扑优化设计

采用有限元分析和结构拓扑优化设计相结合的方法,依据汽车车架的结构受力特性及其材料的性能要求,建立了优化数学模型.在此基础上,基于弯曲板的应力灵敏度分析和性能指标,构建了应力约束下车架拓扑优化准则.最后,开展了车架结构的仿真设计,并得到了合理的结果.     

新型车架的疲劳寿命预测及优化设计

以半挂牵引车车架为研究对象,根据其设计参数,进行了该新型车架的结构设计和模型建立。基于有限元理论,利用有限元分析软件Hypermesh对该车架进行了静态仿真,根据疲劳可靠性理论,结合半挂牵引车所受载荷、疲劳类型以及车架材料参数,采用名义应力法和Miner线性累积损伤法则对该车架进行了疲劳寿命预测。利用有限元和疲劳分析结果,对该车架进行了尺寸优化,达到了轻量化设计的目的,之后通过再次仿真,验证了优化后该车架的静态性能和疲劳可靠性。     

基于有限元法的车架轻量化技术研究

车架刚度对车架结构的承载能力起着决定性作用,车架的模态特性关系到整车的舒适性,因此在保证足够的刚度和良好的模态性能前提下,对汽车车架结构进行轻量化设计具有重要现实和理论意义。本文以某SUV车架为研究对象,首先分析车架各部件灵敏度,选取优化部件;然后,根据结构优化设计理论,分别定义优化设计变量、约束函数和目标函数;最后,建立车架结构轻量化设计的数学模型,对车架结构进行尺寸优化设计。     

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.