基于AMESim的汽车液压减振器失效仿真

针对油液泄漏导致的减振器失效问题,以某国产液压减振器为研究对象,通过分析其结构以及工作原理,建立减振器阻尼力的数学表达式以及AMESim一维仿真模型,仿真得到其不同速度下的示功图以及阻尼特性曲线,并与试验结果进行对比,仿真结果与试验结果能够较好的吻合,表明用AMESim所建立的一维仿真模型真实可靠。基于该仿真模型仿真活塞缝隙、底阀、活塞杆与密封圈缝隙的油液泄漏而导致的减振器失效问题,对比不同状态下的阻尼特性曲线,发现仿真模型可以较好的进行减振器失效的仿真分析,表明仿真模型能够指导实际工程设计以及相关的性能预测。     

车辆油液减振器活塞杆加速度实验与仿真分析

汽车减振器在循环工作过程中,换向冲击振动传递导致的异响是影响车辆舒适性的重要因素之一。通过对减振器异响研究现状进行总结分析,可知减振器异响程度与活塞杆处的振动加速度大小密切相关。针对汽车减振器在行驶时产生的异响,利用MTS测试台采集活塞杆的加速度时域信号进行分析,并建立减振器动力学模型和Bouc~Wen阻尼力模型,应用MATLAB对活塞杆振动进行仿真分析。对比试验与仿真分析结果,验证活塞杆加速度作为评价和分析减振器异响性能指标的可行性,为工程应用中减振器异响的研究提供参考。     

带缓冲簧的汽车减振器外特性及其敏感度分析

基于带缓冲簧的汽车减振器的结构和工作原理,应用流体力学和弹性力学的理论,推导出了受均布载荷作用的环形薄板阀片的挠曲变形解析式,建立了该减振器在复原和压缩工况下阻尼特性的数学模型。在MATLAB环境下对模型进行了模拟仿真,并与实测的减振器的外特性进行了比较分析,仿真与实测结果的一致证明了数学模型正确可靠。同时用该模型分析了减振器活塞杆直径、内部气压、油液温度及摩擦力等因素对其外特性的影响规律及敏感程度,得出的结论可以为减振器的设计和性能预测提供参考。     

基于AMESim的液压减振器异响分析与改进研究

在路面激励下,减振器活塞杆杆端的异常振动激发车体振动,引起结构传递噪声。而区别于无异响减振器,异响减振器的活塞杆杆端振动加速度在285 Hz左右出现一个明显的峰值。对此,建立减振器的AMESim模型,并将仿真结果与试验结果进行对比来检验模型的可信度。最后通过改变橡胶减振垫的阻尼和刚度来减小活塞杆杆端振动加速度在285 Hz左右的峰值,以达到控制减振器异响的目的。     

简式油液减振器空蚀失效发生机理的研究

介绍了减振器结构、工作原理及分析了空程畸变发生过程,通过测量空蚀异响减振器活塞杆头加速度信号的时域波形可进行空程间隙判断,测量空蚀异响减振器的油液及各阀系部件在不同速度点的阻尼力与正常减振器对比分析,得出空蚀发生后减振器油液及各阀系部件对减振器阻尼力影响的对应关系,更换减振器液压油、活塞组件及补偿阀片可以提高减振器阻尼力值恢复减振性能,为减振器异常失效判定和减振效果改进提供依据.     

液压筒式减振器密封圈与气体反弹研究

对减振器油液物理特性进行分析,给出了出现气体反弹减振器使用前、后油液理化特性数值。对油液气穴产生的原因进行了研究,提出了采用多处节流,避免出现局部节流压力过大,使油液出现气穴的措施;对油液层流和紊流运动进行分析,建立了减振器临界速度的概念;对活塞杆摩擦力进行了分析,建立摩擦力解析计算式,提出了采用摩擦因数小的导向器来减小减振器摩擦力的措施;对减振器油封的结构以及吞入空气的机制进行了探讨,提出了增大油封厚度和弹簧卡环弹性,避免前、后唇气室的空气进入减振器缸筒的改进措施。     

电液伺服式减振器测试平台控制策略

针对国内汽车减振器行业生产、检测和研究的迫切需求,为测试减振器在复杂多变的载荷谱作用下的响应性能,搭建了电液伺服式减振器测试平台,研究了测试台伺服控制策略。基于Matlab/Simulink软件,建立测试系统的仿真模型,并对其进行仿真。采用三状态控制策略提高系统响应和跟踪精度。仿真结果和试验结果对比表明,采用该控制策略能保证系统稳定性,提高系统带宽,使测试平台精确测试减振器阻尼力和加速度的衰减。     

车辆双筒式减振器异响研究

针对国内外对减振器异响的分类进行总结,将减振器异响分为两大类:减振器自身异响和减振器传递型异响。基于台架试验采集了不同激振频率下的活塞杆加速度信号并分别在时域和频域内进行分析。建立了二分之一后悬架系统的非线性动力学模型和减振器参数化非线性动力学模型,应用MATLAB仿真对减振器进行异响研究。比较了仿真结果和试验数据,验证了减振器异响试验中对试验数据分析结论的正确性。这种理论与试验相结合的方法可为减振器异响的分析和判定提供参考。     

抗蛇行减振器的模型研究

分析了广泛应用于动车组车辆上的抗蛇行减振器的工作原理,将抗蛇行减振器的力学特征抽象为弹簧、阻尼单元,在Maxwell等效参数模型的基础上,考虑抗蛇行减振器油液阻尼的分段特性,同时考虑橡胶节点刚度和油液刚度,建立液压减振器的分段线性模型。在此基础上,求解抗蛇行减振器的动态阻尼与动态刚度。同时,针对应用在动车组上的某抗蛇行减振器进行动态特性试验,得到减振器的动态阻尼和动态刚度曲线。最后,将分段线性模型的计算结果与两种线性阻尼的Maxwell模型计算结果、试验结果进行对比,验证了模型的准确性。     

动车组用抗蛇行减振器动态特性研究

外界环境温度对减振器油液的黏性有一定的影响,从而对减振器动态特性及车辆动力学性能造成影响.以我国某动车组用抗蛇行减振器为例,对减振器油液温度及其动态及静态性能展开了研究.首先对蛇行减振器结构、工作原理及黏温特性进行了理论分析,再对抗蛇行减振器进行了台架试验认证.研究表明,油液温度对油液的黏性影响很大,进而影响了减振器的动态特性.且随着油液温度升高,减振器吸收的能量越来减少,而其总体动态特性随着温升也有所减小.低温对减振器的影响要远远大于高温,这是由于油液的黏度随着温度升高而减小,且低温对油液黏度的影响大于高温引起的.     

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.