高速压力机机构运动精度可靠性研究

利用矩阵分析理论建立了平面连杆机构精度分析的一般模型,利用可靠性状态函数建立了连杆机构运动精度可靠性指标计算模型,以高速压力机机构为具体对象,建立了曲柄滑块机构运动输出精度模型及其可靠性分析计算模型。算例分析表明:在给定的设计精度下,高速压力机机构在不同的运动状态有着不同的运动误差和不同的运动可靠度。该模型可以定量地给出机构在不同运动状态下的失效概率,对机构的设计与制造具有应用价值。     

基于ADAMS的对心曲柄滑块机构的运动学分析

根据对心曲柄滑块机构的运动原理,利用D-H法建立运动学方程,应用ADAMS建立三维模型,并对其进行运动学仿真,得到了对心曲柄滑块机构中各构件的位移、速度和加速度。通过运动学仿真的结果可证明对心曲柄滑块机构运行的合理性,并且掌握各构件在机构运行时的关联,以灵活地设计对心曲柄滑块机构来满足各种机械装置的需要。     

基于参数辨识法的含间隙曲柄滑块机构模型研究

为解决曲柄滑块机构的间隙问题,提高曲柄滑块机构的位置精度。从曲柄滑块机构的简单机理出发建立其简化模型,再利用传感器去测量曲柄滑块机构各构件的运动物理量;然后,利用参数辨识法对曲柄滑块机构的系统参数进行辨识;最后,建立含间隙的曲柄滑块机构模型并进行仿真分析。对比结果表明,利用参数辨识法建立的模型具有较高的准确性且建模过程简单,为复杂非线性机电系统的建模提供了新的思路。     

基于ADMAS的曲柄滑块机构参数化设计与仿真研究

介绍了运用ADMAS软件建立曲柄滑块机构的三维参数化模型,并利用此模型仿真运动;对虚拟干涉运动进行了分析,得到了机构的位移、速度及加速度曲线。通过动力学仿真分析结果,验证曲柄滑块机构设计的合理性,极大地提高了分析效率,降低了设计和生产成本,探索出了一套基于ADMAS的曲柄滑块机构的设计方法。     

多因素耦合下机构运动精度可靠性仿真试验及寿命评估

针对影响平面机构运动精度因素较多且不能忽视的问题,将影响机构运动精度可靠性因素分为非累积性因素和累积性因素,提出了非累积性因素和累积性因素耦合作用下平面机构的运动精度可靠性仿真试验方法;根据可靠性仿真试验得出了累积性因素中机构允许的最大磨损量,利用Archard磨损模型分析铰链的磨损速率,然后基于最大允许磨损量和磨损速率建立了概率可靠性寿命评估模型和模糊可靠性寿命评估模型,根据该模型分别对机构进行寿命评估,并进行了对比。以曲柄滑块机构为例进行分析,得到了该机构不同铰链间隙下运动精度可靠度以及该机构的可靠性寿命,验证了方法的可行性。     

曲柄滑块机构中偏距对滑块特性影响研究

曲柄滑块机构广泛应用在多种机械中,不同偏距对滑块的运动具有一定影响,文章在理论分析的基础上,利用ANSYS软件建立了曲柄滑块机构的模型,通过对比不同偏距下输出的位移图、速度图和加速度图,分析得出滑块的运动特性,并验证理论分析结果。结果表明偏距对滑块加速度的影响较大,正偏距时有急进特性,负偏距是则有急回特性。     

磨损对曲柄压力机滑块机构运动可靠性的影响

以典型磨损规律，可靠性工程理论以及概率工程设计方法对曲柄压力机的滑块机构运动参数精度进行了分析研究，全面反映了滑块机构铰链连接处的磨损对曲柄压力机运动可靠性的影响。     

Creo在发动机曲柄滑块机构运动仿真分析中的应用

分析了发动机的工作原理,建立了发动机结构中的曲柄滑块机构模型,研究了该曲柄滑块机构在Creo软件环境中的运动仿真分析。实现快速完成机构设计的同时对所设计结果进行了初步分析检验,节约了利用实际产品做实验所需的时间、人力和财力。通过实例验证了参数化设计的曲柄滑块机构在虚拟装配之后的运动学仿真。     

基于Pro/E的曲柄滑块机构运动仿真分析

应用Pro/E软件建立了内燃机曲柄滑块机构的虚拟样机模型,对曲柄滑块机构进行了运动仿真分析,得到了滑块的位移、速度、加速度变化规律,并获得了运动仿真曲线图,为曲柄滑块机构的设计改进提供了重要依据,提高了设计效率,缩短了开发周期。     

由串联四杆机构组成的多连杆压力机下死点精度的研究

针对压力机的工作特点,分析了滑块下死点精度对于工件精度和模具寿命的重要性。利用系统动力学软件ADAMS建立了串联四杆机构的多体动力学模型并作了运动仿真。研究了曲柄长度、曲柄转速、滑块质量和滑块偏心距的变化对滑块下死点位移曲线的影响。仿真结果表明:随着曲柄长度、曲柄转速或者滑块质量的增加,滑块的下死点会向下偏移,且滑块在下死点附近的位移曲线波动会增大;而滑块偏心距的增加对滑块下死点位移的影响具有相反的作用。文中研究结果可对多连杆压力机的开发提供参考。     

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.