起重机焊接接头形式的分析与探讨

针对起重机钢结构焊接接头的载荷特点,介绍了数种常用焊接接头形式,分析常见焊接缺陷及其对强度的影响。以T形接头为例,利用有限元仿真技术,对不同的焊缝形式进行力学分析、对比,从而改进接头形式,优化起重机钢结构焊接接头设计。     

单面角焊缝计算公式的探讨

焊缝连接具有安全可靠、便于施工、经济等特点，它已成为钢结构中最重要和最普遍的连接形式，尤其是工程机械中更是大量采用焊缝作为承载部位的连接形式。钢结构设计规范、起重机设计规范及其他一些专业规范均对焊缝连接的计算作了规定。然而，由于焊缝本身形状不规则，且存在严重     

超大吨位起重机支腿制造过程中焊接裂纹产生原因分析及预防控制

本文对某大型起重机支腿制造过程中焊缝裂纹进行分析并制定焊接裂纹的预防控制措施,提升产品质量及可靠性。从低合金高强度钢母材的焊接性,焊接裂纹的分类及产生原因,预热温度,层间温度,焊接应力等方面分析支腿制造过程中焊缝开裂的原因,结合制造过程中超大吨位起重机支腿厚板焊接的操作方法,探索低合金高强钢厚板焊接过程中焊接裂纹的预防控制措施。     

浅谈钢结构拼装焊接施工工艺流程及施工方案

作为建筑结构主要类型之一,钢结构是由钢材料制作而成,建筑施工过程涉及钢结构的拼装和焊接,拼装焊接质量水平直接影响整个建筑结构的施工质量。本文以实际工程为例,就钢结构拼装焊接施工流程和方案进行了介绍,最后分析了钢结构拼装工艺和焊接工艺质量控制要点。     

建筑钢结构工程低温焊接技术

钢结构工程中的低温焊接（即在冬季施工）一直是学术界和工程界共同关注的课题。钢结构低温焊接对焊缝金属危害的直接表征就是出现裂纹和工作状态下发生脆断，控制不好就会导致焊接质量下降甚至造成不安全隐患，因此受到各方面的高度重视。但根据建筑钢结构焊接工程冬季施工的理论规律，可以确定冬季施焊的两大关键：一是尽量避免三向应力状态下施焊；二是努力提高焊接环境和结构构件的实际温度。     

建筑钢结构焊接影响因素及焊接质量管控

焊接是钢结构制作和安装工程最重要的分项之一,若焊接施工中存在选取方案不当、安全技术措施不全、针对性和可操作性差等问题,将造成焊缝质量差,为后续的施工留下质量和安全隐患,进而导致经济损失或人员伤亡。鉴于此,围绕建筑钢结构的焊接工艺以及性能进行分析,并对钢结构焊接管理的重要性、材料性能、技术应用等方面展开研究,以此为我国技术创新与提升工艺水平创造良好的条件。     

水工钢结构闸门焊缝质量控制与检测

水利水电工程中,水工钢结构闸门制造与安装质量很大程度上受焊接作业的影响,需要认真做好焊缝质量控制与检测工作,强化水工钢结构闸门焊接作业监管力度。从水工钢结构闸门焊接流程与工艺技术出发,着重分析焊缝质量控制的有效措施和焊缝质量检测的科学方法,从而构建焊接质量控制与检测体系,为水工钢结构闸门的安全稳定运行提供必要保障。     

桥门式起重机焊接质量控制策略

介绍桥门式起重机制造过程中焊接质量控制的要点,指出焊缝外部及内部缺陷都会对桥门式起重机的产品质量产生不良影响,所以必须在培训操作人员,执行焊接工艺规范上加强管理,并且要针对实际焊接环境合理调整焊接工艺规范,避免湿度、温度等环境因素对焊缝质量产生不良影响。     

焊接机械手在起重机制造上的应用

介绍一种智能焊接机械手,克服起重机主梁质量大、体积大、差异化大、组装精度差、焊缝形式复杂等因素,实现起重机主梁和端梁内部隔板双面断续焊缝的自动寻位、定位与焊接。将焊工从高污染的梁盒内部解脱出来,很大程度改善工人的作业环境,并提高焊缝尺寸精度、焊缝质量。加上梁盒4条纵缝采用双枪龙门焊,实现起重机主、端梁90%的焊缝自动化焊接。     

起重机轨道闪光焊焊接技术

由于起重机轨道通常采用高碳中锰的U71Mn钢轧制而成,手工焊接性能较差,焊缝接头容易产生裂纹、夹渣等缺陷,故对轨道传统手工焊接工艺改革非常必要.文中引进高铁常用的轨道焊接技术闪光焊,其特点是焊接速度快,接头质量稳定,是一种成熟的轨道焊接形式.研究闪光焊运用于起重机轨道焊接,并通过多条轨道焊接试验,形成详细的闪光焊轨道焊...     

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.     

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....     

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.