EN1591法兰计算标准简介(二)

EN1591—1《法兰及其接头-垫片圆形法兰连接的设计规则——第一部分：计算方法》是欧盟发布的压力设备指令(PED)的协调标准和EN13445《受火压力容器》收录的法兰设计方法。本文对EN1591—1新的设计思路和计算原理作一介绍,并与传统的ASME规范方法进行对比。     

压力管道与容器密封结构螺栓预紧载荷确定方法的探讨

基于对ASME规范与EN1591-1中螺栓法兰接头设计计算方法的比较,分析了确定螺栓载荷中存在的问题。通过有限元分析,计算接头各元件柔度,并建立密封结构的载荷-变形曲线,从而提出了确定合适的螺栓预紧载荷的方法。     

螺栓法兰连接设计方法对比分析及国内研究现状综述

螺栓法兰连接接头是工业设备和管道中最常用的静密封连接方式,因为其结构简单和拆装检修方便的特点,在炼化、制药、食品等众多行业中得到了广泛的应用.简要介绍了螺栓法兰连接系统设计方法的发展历程,重点对比分析了3种主要螺栓法兰设计方法——Waters法、PVRC法以及EN13445-3附录G方法(EN1591法)的异同.ASME规范Ⅷ-1篇附录2给出了法兰强度的校核方法,但不能保证法兰连接密封的泄漏率;EN13445-3附录G方法不仅给出了螺栓法兰强度计算方法,还考虑了螺栓法兰连接的紧密性.近年来我国的专家学者在垫片泄漏计算模型、垫片性能参数及测试方法研究、螺栓载荷计算等方面取得了众多成果,也是探讨的重点内容.最后对基于控制泄漏率的螺栓法兰连接设计方法研究工作的重点方向进行了展望.     

不同螺栓力计算方法的适用工况研究

针对法兰螺栓力的计算方法,对比分析3种计算方法的计算流程和结果的差异,并运用有限元方法分析3种螺栓力计算方法在不同工况下的垫片应力,以此研究3种螺栓力计算方法对不同工况的适应情况。结果表明:3种计算方法都适用于不同内压下的工况,但m、y系数法和PVRC系数法对内压的变化更为敏感;EN1591法适用于高温以及由外加弯矩的工况,而m、y系数法和PVRC系数法不适用;对于有泄漏率要求的工况EN1591和PVRC系数法更为合适。     

基于prCEN/TS1591-3的金属与金属接触型法兰接头的计算

为了使金属与金属接触型（MMC）螺栓法兰接头的设计计算更为精确,欧洲标准协会（CEN）在2006年发布了适用于MMC型螺栓法兰接头的计算标准prCEN/TS1591-3。介绍prCEN/TS1591 3计算方法,运用该方法的力学模型、计算流程以及计算相关的密封垫片参数,并给出对应的算例, 为MMC型螺栓法兰接头的计算提供参考。     

Taylor-Forge法与欧盟法兰设计另一方法对比分析

介绍了传统的基于Taylor-Forge法的法兰连接系统设计规范,同时简述了美国压力容器委员会和欧洲标准协会的研究成果及进展,并对欧盟标准EN 13445附录G法兰设计另一方法作了详细介绍。给出实例,分别采用传统法和EN 13445附录G两种法兰设计方法进行计算,通过对两种计算结果分析发现,两种方法都能保证法兰连接的强度和一定的密封性,但EN 13445附录G基于泄漏率准则,提高了法兰连接螺栓接头的密封性能,为国内法兰设计研究者提供一定的参考经验。     

某风道安装梁强度仿真计算及优化

根据标准EN 12663-1:2010+A1:2014《铁路应用—铁路车辆车身的结构要求—第1部分:机车和客运车辆》对设计的某列车风道安装梁进行静强度仿真计算和评估,结果表明初始设计方案不满足强度要求,对安装梁结构优化后满足强度要求.     

国内外钢制管法兰国家标准分析

国际上有两大通用的钢制管法兰标准体系,一是以EN 1092《法兰及其连接件按PN标注的管、阀门、配件及附件用圆形法兰》为代表的欧洲管法兰标准体系(公称压力用PN标识),二是以ANSI/ASME B 16.5:2013《NPS 1/2至NPS 24公制/英制标准的管法兰和法兰管件》和ANSI/ASME B 16.47:2011《大直径钢法兰NPS 26~NPS 60米制/英寸标准》为代表的美洲管法兰标准体系(公称压力用Class标识)。这两大系列的法兰在材料、尺寸、压力-温度等级等各方面都有明显差异,在实际应用中不能互换使用。本文将重点分析钢制管法兰国家标准与国际及国外先进标准的主要差异,以指导标准的使用。     

EN 1993-1-6标准中的壳体失稳设计方法简述

数值模拟计算能力和水平的提高为外压壳体失稳复杂理论应用到实际设计方法中提供了可能,应用数值模拟进行设计逐步在标准中引用并不断完善。与其他标准相比, EN 1993-1-6（2007）《壳结构的强度与稳定》对数值模拟在设计上的应用给出了更为详细的规定。对壳体失稳设计,EN 1993-1-6提出了3种不同的设计方法：公式计算方法、LBA-MNA方法以及GMNIA方法。为研究EN 1993-1-6的壳体数值模拟设计方法的可行性,对其进行了简要介绍,并通过10组算例与GB 150,ASME Ⅷ-2,EN 13445等标准进行对比,结果显示,EN 1993-1-6的数值模拟的设计许用值均高于GB 150的设计许用值,而与ASME Ⅷ-2和EN 13445相比,设计许用值则比较接近,这表明EN 1993-1-6规定的数值模拟设计方法有着比GB 150更好的经济性,是一种先进的设计方法。     

JB/T 89—2015《管路法兰用金属环垫》解读

正工业和信息化部于2015年10月10日发布了JB/T 89—2015《管路法兰用金属环垫》。该标准由全国管路附件标准化技术委员会(SAC/TC 237)归口,于2016年3月1日实施。JB/T 89—2015《管路法兰用金属环垫》是对JB/T 89—1994《管路法兰用金属环垫》的修订。与旧标准相比,新标准主要变化见下文。     

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.     

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....     

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。     

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.