激光拼焊板成形极限图性能分析

对汽车用冷轧钢板进行了等厚激光拼焊试验，并进行了成形极限图性能分析和将等厚激光拼焊板进行汽车零部件实冲试验。结果表明：尽管激光拼焊板激光焊缝部位由于焊缝的硬化其成形性能较母材有所降低，但通过激光焊缝位置的合理设计，激光焊缝的应变安全裕度能够满足汽车零部件的成形要求。     

差厚高强度钢拼焊板成形性能研究

拼焊板是一种先进的制造工艺技术,就不等厚高强钢拼焊板的成形性能进行了研究.针对焊缝处于拉伸试件的不同方向进行了拉伸试验,并与母材的拉伸变形性能进行了比较,给出了不等厚高强钢拼焊板塑性拉伸变形性能的力学参数.进一步分析了不同焊缝方向对拼焊板塑性拉伸变形性能的影响.同时通过杯突试验对不等厚高强钢拼焊板的胀形性进行了测试,并与母材的胀形性能进行比较,试验表明,焊缝的位置对不等厚拼焊板的胀形性有一定的影响,最后讨论了焊缝在杯突试验中移动的规律及原因.     

圆弧焊缝拼焊板成形性能的影响因素分析

为了提高拼焊板的成形质量,针对固定圆弧半径R=180 mm差厚拼焊板,利用Dynaform数值模拟仿真技术与正交设计相结合的方法,对影响横向圆弧焊缝拼焊板成形质量的强度比、凸凹模间隙、薄侧压边率、摩擦因数、总压边力、板厚比因素进行了分析。结果表明:强度比、摩擦因数、总压边力及板厚比对成形结果影响相对较大。随着薄侧母材强度的提高,其抵抗变形的能力不断增强,使得薄侧母材变形程度降低导致焊缝移动量有所降低,拼焊板成形质量有所提高。摩擦因数和总压边力对拼焊板的成形性能的影响并不是很大,但过大的摩擦因数和过大的总压边力会影响两侧母材的材料流动性,进而影响板料的最终成形质量。在设计拼焊板时,板厚搭配应仔细考虑,一般把板厚比取在1.0~1.0到1.0~1.4这个范围之间成形较为稳定,过小和过大的板厚比不利于拼焊板成形。     

焊缝影响拼焊板成形性的母材匹配研究

运用数值模拟的方法并结合胀形试验分别研究了同质差厚拼焊板在不同板厚比以及异质等厚拼焊板在不同强度比情况下,焊缝参数对拼焊板成形能力的影响规律,确定了焊缝对拼焊板成形能力产生主要影响的板厚比及强度比范围。结果表明:焊缝对拼焊板成形能力的影响是具有一定母材匹配范围的。当板厚比或强度比小于1.3时,焊缝是影响拼焊板成形能力的主要因素,应从改善焊缝性能方面着手提高拼焊板成形能力;当板厚比或强度比达到或大于1.3时,母材差异程度是影响拼焊板成形能力的主要因素,应从合理搭配母材以及优化成形工艺方面着手设计拼焊板。     

焊缝形式对拼焊板性能影响的研究

研究焊缝形式对拼焊板的性能和成形性的影响,利用ABAQUS有限元软件仿真和进行单向拉伸试验对激光拼焊板强度、综合延伸率进行分析、验证,对拼焊板基板板材、焊缝及其焊缝热影响区进行金相学和硬度研究,运用Dynaform有限元软件对其冲压成形极限进行仿真并进行冲压试验来验证焊缝对拼焊板成形性的影响.试验结果表明,对于同质同厚...     

焊缝对同质等厚拼焊板成形能力的影响规律研究

焊缝对同质等厚拼焊板成形能力的影响远大于母材强度或厚度存在差异的拼焊板。运用数值模拟方法分别对直线焊缝和圆弧焊缝同质等厚拼焊板进行胀形试验,主要研究了焊缝K值、焊缝n值、焊缝位置以及圆弧焊缝半径对拼焊板成形能力的影响规律。并通过正交试验以及极差分析得到了焊缝各因素影响拼焊板成形能力的主次顺序。研究结果表明,焊缝应变硬化指数n值是影响拼焊板成形能力的关键因素,应从增大焊缝n值入手制定母材拼焊工艺。此外,对于同质等厚拼焊板,圆弧焊缝相对于直线焊缝具有更好的成形能力。因此,在相同的工艺条件下,用圆弧焊缝代替直线焊缝可以适当的提高拼焊板的成形能力。     

激光拼焊设备的设计与开发

激光拼焊是将两块或多块不同材质、不同厚度、不同涂层的材料,通过激光焊接成一块理想的整体板,以满足零部件对材料性能的不同要求。激光拼焊在汽车工业中已成为标准工艺,车身面板经激光拼焊后再进行冲压,这样制成的面板结构能达到最合理的金属组合。激光拼焊板工艺不仅能够降低汽车的制造成本、     

拼焊板在汽车悬架及车身壳体中的应用及进展

介绍了拼焊板的等离子拼焊工艺及激光拼焊工艺,给出了等离子拼焊板在汽车悬架本体中的应用案例,概括了激光拼焊板在车身壳体上的应用情况;最后,综述了拼焊板的成形性研究进展及发展趋势.     

新能源汽车结构轻量化关键工艺的研究

基于《节能与新能源汽车技术路线图》,从焊接工艺和成形工艺两方面对新能源汽车结构轻量化的关键工艺进行研究。介绍了激光拼焊板、铝合金拼焊板、冷金属过渡焊接、异种金属点焊,分析了连续变截面板成形与内高压成形,为相关行业和技术人员提供参考。     

压边力对圆弧焊缝拼焊板成形性能影响研究

成形性能下降是汽车轻量化过程中遇到的重要问题之一。针对固定圆弧半径R=180mm差厚拼焊板,利用Dynaform数值模拟仿真技术,对横向圆弧焊缝拼焊板在压边力情况下的成形性能进行了研究。分析了压边力在随位置变化情况下,圆弧焊缝拼焊板的成形能力。研究发现在圆弧焊缝拼焊板的冲压成形过程中,在薄侧加载大的压边力有利于拼焊板成形及抑制薄厚板的起皱现象。在拼焊板成形分析中,无论薄侧压边力固定还是厚侧压边力固定,圆弧焊缝拼焊板的焊缝移动都随着薄侧压边力的增大而得到控制,但进一步增大薄侧压边力,焊缝移动量反而增大。在压边力控制焊缝移动提高拼焊板成形方面,不是单纯的增大薄侧压边力就会提高拼焊板的成形质量,薄厚两侧的压边力必须适当才能有效控制焊缝的移动量,进而提高拼焊板的成形质量。在圆弧焊缝拼焊板成形过程中,由于圆弧焊缝的存在,拼焊板在薄厚两侧压边力为140/150k N的情况下成形性较好。拼焊板的成形质量不仅与薄厚两侧施加压边力的大小有关还与薄厚两侧的面积有关。     

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.