焊接接头母材区断裂韧度COD特征值研究

采用三点弯曲试样对ＡＰＩＸ５２管线钢焊接接头母材金属区断裂韧度ＣＯＤ特征值进行了测试研究。研究结果表明，焊缝金属的力学性能对母材金属的起裂韧工，裂纹扩展阻力，撕裂模量及延伸区宽度有很大的影响，其影响程度取决于裂纹离焊缝的距离，离焊缝愈近，影响愈大，裂纹尖端的延伸区宽度和起裂韧度具有良好的线性关系。     

基于BS7910含缺陷X80钢焊接管道的安全评定

根据英国标准BS7448,制备带预制疲劳裂纹的三点弯曲(three point bent,TPB)标准试样,对X80管线钢焊缝、热影响区和母材进行0℃断裂韧度试验,根据CTOD(crack tip opening displacement)试验结果,结合材料的力学性能、载荷条件,采用英国BS7910结构完整性评定方法的1A、2A评定曲线,针对焊缝内部的深埋裂纹,对X80钢管道焊缝进行安全评定。通过迭代计算确定含有深埋裂纹X80钢管道焊缝中的容许裂纹尺寸。     

冲击吸收功在海底油气管道安全评定中的应用

采用欧共体提出的结构完整性评定方法，对含表面裂纹和埋藏裂纹的AP15L X65管线钢焊接接头进行安全评定。评定根据夏比冲击试验得到冲击吸收功。从而估算断裂韧性KIC来建立评定点进行零级评定；同时根据裂纹尖端张开位移(CTOD)试验结果进行一级评定并对二者进行了比较。评定结果表明，不论是采用零级或是一级评定，各评定点均在评定曲线定义的范围内，说明该结构是安全的。因此，在不能得到其他断裂韧性值的情况下，采用冲击吸收功进行零级评定是切实可行的，且其结果偏安全。     

焊接接头韧度CTOD评定的适用性与允许值研究

对厚钢板两种焊接工艺焊接接头中的焊缝材料和热影响区材料进行拉伸试验。发现各自的拉伸曲线都可视为理想弹塑性，符合Wells提出裂纹尖端张开位移（crack tip opening displacemem，CTOD）理论的假设条件。因此，证明CTOD试验评定焊接接头韧度的适用性。提出确定钢结构焊接接头CTOD允许值的“母材参考法”和“类比法”，为在钢结构的设计和建造中合理地确定焊接接头韧度指标提供方法。     

基于显微组织的多层焊接接头断裂韧性试验研究

对NiCrMoV钢多层焊接接头进行了准静态断裂性能试验,试验中发现埋弧焊焊缝断裂韧性J值分散性较大。根据焊接试样韧性断裂和脆性断裂的情况,分组拟合J-R阻力曲线和计算有pop-in效应的尺寸敏感断裂韧度Jc(25)值。分别对呈现韧断和脆断的多层焊接试样断口的启裂部分进行扫描电镜分析,发现多层焊接焊缝的断裂韧性与试样预制裂纹尖端在焊缝接头中的位置有很大关系。对多层焊接接头各组织的成因以及对断裂韧性的影响进行了分析和研究,可知多层焊缝的粗大柱状晶、再结晶粗晶和再结晶细晶区交替存在的复杂组织是焊接接头断裂韧性分散性大的根本原因。     

厚钢板焊缝强度匹配对韧度影响的试验方法

提出了研究厚钢板焊缝强度匹配对韧度影响的试验方法：用“直接测量法”确定焊缝强度匹配系数；用裂纹尖端张开位移（CTOD）断裂韧度作为焊缝材料韧度的指标。用“直接测量法”确定了低合金高强钢S355ML钢板（厚65mm）自动埋弧焊和手工电孤焊的焊缝强度匹配系数，同时将这两项焊接工艺的对接焊缝制成全厚度断裂韧度试样，运用裂纹尖端张开位移试验方法测定其焊缝中心的断裂韧度。结果表明，厚钢板焊态对接焊缝，低匹配焊缝具有较高的韧度，高匹配焊缝的韧度比较低。     

X70管线钢管环焊接头在低约束条件下的断裂韧性

针对基于应变设计的X70管线钢管,采用单边缺口拉伸试验对该钢钢管环焊缝金属及热影响区的裂纹尖端张开位移进行研究,获得了裂纹延性扩展过程的断裂阻力曲线,并对热影响区试样的试验结果进行了有效性验证。结果表明:热影响区试样的裂纹尖端距熔合线的距离在0.5mm以内,焊缝金属和热影响区试样的断裂阻力曲线分别为δ=1.395 78(Δa)0.783 35,δ=1.553 38(Δa)0.821 75;采用单边缺口拉伸试验能准确测出管线钢环焊接头在低约束条件下的断裂韧性;试验结果可以为管线基于应变设计和工程临界评价提供依据。     

X65管道焊缝断裂韧性统计分布的计算机分析

对X65管线钢环焊接头的断裂韧性δc进行了试验测定，自行编制了确定接头断裂韧性δc概率统计分布的计算机分析程序。将试验数据输入计算程序，只需一次计算就可确定断裂韧性是否符合三种常用分布(正态分布、对数正态分布、威布尔分布)之一，该程序对快速、准确地确定材料力学性能的概率统计分布以及对结构进行可靠性分析具有重要应用价值。计算表明，X65管线钢环焊接头的断裂韧性δc符合正态分布、对数正态分布和威布尔分布，但威布尔分布是描述管道焊缝金属断裂韧度指标δc的最佳拟合分布函数。     

焊缝非匹配海底管线缺陷在不同标准下的安全评定研究

本研究在给定裂纹尺寸和载荷条件下,根据CTOD(裂纹尖端张开位移)试验结果,先后采用英国标准协会提出的BS7910标准和欧共体提出的结构完整性评定方法SINTAP,针对EH36管线钢焊接接头焊趾处的表面裂纹进行评定。根据拉伸试验结果,建立了管线钢焊接接头的评定曲线。评定结果表明,应用BS7910标准进行评定时,各评定点不在评定曲线定义的范围内,说明该结构不能验收;而使用SINTAP方法评定,各评定点均在评定曲线定义的范围内,此时结构是可以接受的。本次研究充分说明SINTAP在强度不匹配方面要求更加详细,评定结果保守性相应地更低。     

X80管线钢焊接接头的硫化氢应力腐蚀试验研究

采用X80管线钢焊接接头制作楔形张开加载（WOL）试样，在硫化氢介质中进行恒位移应力腐蚀试验，分别测得母材、焊缝和热影响区的临界应力强度因子KISCC和裂纹扩展速率da／dt。试验结果表明，热影响区的‰最小，裂纹扩展速率最大，具有较差的抗应力腐蚀开裂的能力，是应力腐蚀开裂的薄弱环节。且通过对X80管线钢焊接接头的显微组织观察和基本力学性能研究，对影响X80钢应力腐蚀影响因素提供了试验依据，并对试验结果予以验证。     

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.