基于可靠指标的密封螺栓静强度设计

考虑内压容器垫片密封螺栓静强度和载荷的模糊不确定性,应用模糊等效随机的信息熵理论,将密封螺栓的模糊静强度和模糊载荷分别等效为随机静强度和随机载荷;根据等可靠度的观点,确定了密封螺栓静强度在不同工况时的可靠指标,建立按可靠指标进行密封螺栓静强度设计的方法,得到其静强度安全系数。研究表明,(1)按静强度可靠指标得到了计算密封螺栓最小直径的公式。(2)密封螺栓在预紧、正常操作、气压试验与液压试验时,屈服强度的可靠指标分别为2.486 0、2.486 0、1.920 4与0.815 0,抗拉强度的可靠指标分别为5.644 6、5.644 6、5.644 6与4.270 0。(3)基于满足屈服和抗拉强度的可靠指标,螺栓屈服与抗拉强度的最小安全系数分别为1.45与1.90。     

钢制薄壁内压容器模糊静强度的可靠度

基于信息熵中模糊性度量与随机性度量相等可实现模糊变量等效随机变量的原理,将钢制薄壁内压容器的模糊静强度和模糊载荷等效为随机静强度和随机载荷,讨论按我国标准设计与制造的钢制薄壁内压容器模糊静强度,在最苛刻压力试验条件下的最小可靠度.研究表明,在最苛刻的气压与液压试验条件下,(1)钢制薄壁内压圆筒模糊屈服强度可靠度的最小值分别为0.972 60和0.792 5,模糊爆破强度可靠度的最小值分别为0.999 999 991 40与0.999 989 75.(2)钢制薄壁内压球形容器模糊屈服强度可靠度的最小值分别为0.999 337 0与0.903 25,模糊爆破强度可靠度的最小值分别为0.999 998 87与0.999 907 95.(3)扁平绕带容器模糊屈服强度可靠度的最小值分别为0.993 540与0.932 28,模糊爆破强度可靠度的最小值分别为0.999 999 153与0.999 977 4.     

基于信息熵的钢制薄壁内压容器试验压力

基于钢制薄壁内压容器模糊静强度的信息熵分析,从控制钢制薄壁内压容器模糊静强度在正常操作与压力试验时模糊可靠度的角度,对其安全系数与试验压力系数进行探索。研究表明,从等可靠度的观点,(1)钢制薄壁内压容器模糊屈服强度可靠度在正常操作时应不低于0.99354,在气压与液压试验时应分别不低于0.97260与0.7925;模糊爆破强度可靠度在正常操作时应不低于0.99999999140,在气压与液压试验时应分别不低于0.99999999140与0.999990226。(2)钢制薄壁内压圆筒屈服安全系数应不小于1.45,抗拉安全系数应不小于1.80;钢制薄壁内压球形容器屈服安全系数应不小于1.40,抗拉安全系数应不小于1.85;扁平绕带式容器屈服安全系数应不小于1.35,抗拉安全系数应不小于1.95。(3)钢制薄壁内压圆筒试验压力系数在气压试验时应不小于1.04,但不大于1.16;在液压试验时应不小于1.04,但不大于1.26。钢制薄壁内压球形容器试验压力系数在气压试验时应不小于1.04,但不大于1.19;在液压试验时应不小于1.04,但不大于1.26;扁平绕带式容器试验压力系数在气压试验时应不小于1.04,但不大于1.16;在液压试验时应不小于1.04,但不大于1.28。     

钢制压力容器静强度可靠性设计研究

墓于信息熵理论,分析钢制压力容器的最苛刻压力试验条件;得到五种结构容器模糊静强度在最苛刻压力试验时可接受的可靠度;从等可靠度的观点,确定六种结构容器模糊静强度在压力试验和正常操作时的许用可靠度;建立按模糊静强度许用可靠度确定超压限制系数、安全系数及试验压力系数的钢制压力容器静强度可靠性设计的关健技术.采用25组钢制薄壁内压容器屈服强度和58组钢制薄壁外压容器临界失稳强度的试验数据,验证文中方法的有效可行性.     

基于许用可靠度的超高压圆筒爆破安全系数

基于钢制薄壁压力容器的可靠性研究,确定了超高压圆筒在耐压试验与正常操作状态下的许用可靠度系数,采用应力-强度干涉模型,建立了超高压圆筒爆破安全系数、试验压力系数与许用可靠度系数三者之间的关系。研究表明:1)超高压容器爆破压力许用可靠度系数,在耐压试验时的范围应不小于3.31且不大于6.81,在正常操作时应不小于3.91且不大于7.57。2)基于满足许用可靠度系数范围,采用福贝尔(Faupel)公式设计径比在1.33与4.71之间的超高压圆筒,当圆筒材料的屈强比在0.4997与0.8852之间时,爆破安全系数的最小值为2.50,对应的试验压力系数应不小于1.08且不大于1.25。     

兆瓦级风力发电机主轴结构强度及可靠性分析

针对某1.5 MW双馈式风力发电机,利用Ansys的参数化建模语言APDL对其主轴进行参数化建模,得到风机主轴参数化模型以及命令流文件。根据风机主轴的载荷数据,校核了风机主轴在16组极限工况下的静强度,结果显示主轴工作应力在工况dlc 2.1b最大,为237.086 MPa。最大工作应力小于许用极限,主轴符合静强度要求。考虑到实际情况下风机主轴结构尺寸参数、材料力学参数以及所受载荷参数的随机性,利用专门的概率分析软件NESSUS联合Ansys,对风机主轴进行基于静强度的结构可靠性分析,结果显示风机主轴的结构可靠性P_R=0.999 224 4,略小于要求的0.999 9。根据灵敏度分析结果,提高屈服强度均值,降低屈服强度标准差,提高尺寸参数R_2均值可增加风机主轴结构可靠度。     

钢制薄壁内压容器静强度最小安全系数的研究

考虑到容器静强度与载荷的不确定性,得到钢制薄壁内压容器的安全系数与试验压力系数,是创建压力容器可靠性设计理论的重要内容;根据容器静强度在最苛刻耐压试验时的许用可靠度,确定了容器在耐压试验和正常操作时的最小许用可靠度范围;得到了用于计算钢制薄壁内压容器静强度最小安全系数与试验压力系数的方法。     

钢制薄壁内压容器的压力试验超压限制系数

基于钢制薄壁内压容器模糊静强度可靠度的信息熵分析,对其在最苛刻压力试验时的超压限制系数进行研究,导出该系数的理论计算公式。如果要求钢制薄壁内压容器屈服强度的模糊可靠度在最苛刻气压与液压试验时分别为0.97260与0.7925,爆破强度的模糊可靠度在最苛刻气压与液压试验时分别为0.99999999140与0.999990226;则研究表明:(1)钢制薄壁内压圆筒在气压与液压试验时的超压限制系数在屈服失效准则下应分别不大于0.800与0.900,在爆破失效准则下应分别不大于0.640与0.719。(2)钢制薄壁内压球壳在气压与液压试验时的超压限制系数在屈服失效准则下应分别不大于0.848与0.943,在爆破失效准则下应分别不大于0.581与0.680。(3)扁平绕带容器在气压与液压试验时的超压限制系数在屈服失效准则下应分别不大于0.858与0.971,在爆破失效准则下应分别不大于0.538与0.658。     

含开孔复合材料构件的安全系数分析

通过对T300/5405含孔复合材料层压板拉伸强度试验数据的统计分析,指出开孔后拉伸强度符合两参数Weibull分布。在此基础上,讨论了开孔强度服从Weibull分布,应力服从正态分布时,复合材料基于基准许用值安全系数与可靠度之间的关系。给出了一些常用复合材料在不同应力变异系数和不同可靠度要求下的A基准值和B基准值安全系数的统计取值范围。试验数据对比分析结果表明:含孔层压板与光滑层压板在获得同样可靠度的要求下,安全系数取值范围相近。并且在相同可靠度要求下,A基准值安全系数小于B基准值安全系数。     

含开孔复合材料构件的安全系数分析

通过对T300/5405含孔复合材料层压板拉伸强度试验数据的统计分析,指出开孔后拉伸强度符合两参数Weibull分布。在此基础上,讨论了开孔强度服从Weibull分布,应力服从正态分布时,复合材料基于基准许用值安全系数与可靠度之间的关系。给出了一些常用复合材料在不同应力变异系数和不同可靠度要求下的A基准值和B基准值安全系数的统计取值范围。试验数据对比分析结果表明:含孔层压板与光滑层压板在获得同样可靠度的要求下,安全系数取值范围相近。并且在相同可靠度要求下,A基准值安全系数小于B基准值安全系数。     

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.