共查询到19条相似文献,搜索用时 93 毫秒
1.
激光电弧复合焊是一种低成本、高适应性的焊接方法,在铝合金、不锈钢等难焊金属中,可不同程度的减少和消除了焊接缺陷。以A6N01铝合金为研究对象,进行了焊接坡口设计,研究了间隙变化量对焊缝成形的影响以及进行了焊接接头残余应力检测。结果表明:为了满足激光-MIG复合焊接的工艺,需要设计单独的坡口型式。通过降低焊接速度,间隙为2.0 mm时仍可获得良好焊缝成形。MIG焊接,激光-单丝MIG焊接、激光-双丝MIG焊接,沿着焊缝的应力除个别区域外,皆为小于150MPa的压应力,激光-单丝MIG焊接的焊件整体应力值较小。 相似文献
2.
采用熔化极惰性气体保护焊(MIG焊)工艺对A7N01铝合金T形接头两侧分别进行单、双道焊接,研究了接头的显微组织、显微硬度和疲劳性能,分析了单、双道焊接的影响。结果表明:单道焊侧从熔合区至焊缝中心的显微组织依次由细晶、柱状晶和等轴晶组成,双道焊侧熔合线附近的显微组织与单道焊侧的相似,在两道焊缝交界处形成了柱状晶,且第一道焊缝的柱状晶相对粗大;接头两侧的母材区均存在软化区,且单道焊侧的软化程度更明显;两侧分别为单、双道焊接接头的疲劳寿命比两侧均单道焊的短,疲劳裂纹萌生于焊趾表面并向内部扩展,断口呈现准解理断裂和韧性断裂的混合断裂模式。 相似文献
3.
4.
铝合金焊接接头疲劳评定的应力平均法 总被引:2,自引:0,他引:2
应力平均法(the stress averaging approach,简称SAA)是局部应力方法之一,文中采用此方法对3A21铝合金焊接接头进行疲劳评定,用有限元计算局部应力值,建立试验结果和评定结果的S-N曲线,并分析接头形式、焊趾半径对疲劳强度的影响。结果表明,SAA法评定的结果是偏于安全的,但Neuber建议把焊趾处视为尖锐缺口(即令ρ=0,ρ^*=0.15mm),在工程上有一定的适用件,在理论上并不完全正确。这样在焊趾处将产生较大的应力集中,由此得到的局部应力值远远大于实际值。接头形式对采用名义应力幅值△σ表示的疲劳强度有较大影响;焊趾是决定焊态接头疲劳性能的关键部位,应力集中区的最大应力存在于焊趾部位。 相似文献
6.
在不同下压量(0.3,0.7,1.0 mm)下对7N01铝合金进行搅拌摩擦焊,研究了下压量对接头截面形貌、拉伸性能、抗撕裂性能及疲劳性能的影响。结果表明:下压量对7N01铝合金搅拌摩擦焊接头的拉伸性能影响不大;当下压量为0.7,1.0 mm时,接头的启裂能、裂纹扩展能及撕裂强度均相近,但当下压量为0.3 mm时,接头焊缝区域的启裂能、裂纹扩展能及撕裂强度均显著降低;随着下压量的增加,焊接接头疲劳强度增大;当下压量为1.0 mm时焊接接头的疲劳性能及抗裂纹扩展性能最优。 相似文献
7.
8.
9.
焊接接头疲劳评定局部法研究进展 总被引:1,自引:2,他引:1
焊接接头疲劳评定的“局部法”(local approach)是近年来疲劳评定研究的重要方向。这种方法的基本原理是采用与疲劳断裂直接相关的应力集中区域应力场的“局部参量”作为疲劳断裂的控制参量,建立具有普遍适用性的“局部参量”与循环次数N表示的S-N曲线,据此进行疲劳强度和疲劳寿命预测与评定。由于局部法包括焊接接头局部焊缝几何细节等因素,因而更能反映焊接结构疲劳断裂的实际情况,受到国际焊接学会和工程界的普遍重视。目前已发展多种疲劳评定的局部方法,如缺口应力强度因子法(N-SIF)、等效应力强度因子法(E-SIF)、临界距离法(CDM):包括点(PM)、线(LM)、面(AM)和体积法(VM)、临界面法和包括应力梯度的体积法等。本文对这些局部法的基本原理、分析步骤及影响因素进行简要探讨。 相似文献
10.
11.
Guoqing Gou Nan Huang Hui Chen Hongmei Liu Aiqin Tian Zhicheng Guo 《Journal of Mechanical Science and Technology》2012,26(5):1471-1476
For high speed trains, safety is of utmost importance. Salt fog corrosion, intergranular corrosion tests were employed to observe the corrosion behavior of welded joint of A6N01S-T5 aluminum alloy of high-speed trains. Tensile strength and hardness changed after corrosion was tested. The micro morphologies were observed by metalloscope and laser confocal scanning microscope (LCSM). The corrosion loss and corrosion loss ratio were also investigated. The results showed that the heat affected zone (HAZ) was the most sensitive to corrosion in welded joint in the salt fog corrosion test. The potential of the corrosion of the intermetallic compound on the surface was different from the Al matrix potential, which easily generated corrosion micro-batteries that generated the corrosion pit. The weld zone was the most sensitive to corrosion in the welded joint in the intergranular corrosion test, because much corrosion produced an intermetallic phase such as CuAl2, MgZn2, Mg5Al8, which formed the deficient Cu or Mg zone potential. The potential is low, which acted as an anode and corroded. The residual stress test on the weld of the A6N01S-T5 of the W1 of the exterior surface of roof of high speed train showed there was distributed high tensile stress and compressed stress in the weld zone, HAZ zone and matrix zone. The defects will spread under the high stress and make the corrosion become severe. 相似文献
12.
13.
对A5083铝合金焊接接头进行抛丸处理,测试抛丸前后焊接接头的表面残余应力,并对焊接接头的硬度、拉伸强度、冲击强度以及微观组织进行了分析研究。研究结果表明,经抛丸后,工件表面形成压应力层。不同接头型式的表面残余应力值都明显下降。抛丸后,硬度、拉伸强度和显微组织变化不大,没有特定规律。抛丸处理的影响深度一般不超过0.3 mm,表面压应力层对内部的组织及机械性能没有显著影响。抛丸对A5083铝合金焊接接头的断裂行为没有大的影响,因此可以将抛丸处理作为一种有效的残余应力降低或者消除工艺在高速列车上使用。 相似文献
14.
15.
针对轨道车辆铝型材焊接接头缺乏标准化管理、重复建模等问题,设计开发了一个3D铝型材焊接接头库,实现了三维接头模型及其数据信息的有效管理。首先在Pro/E系统中创建了具有参数化功能的样板模型;然后利用Microsoft Access创建了数据库,用ADO数据库访问接口技术解决了与Pro/E系统之间的通信;最后在Visual C++编译环境下,调用Pro/Toolkit应用程序提供的相关函数,编制了菜单和用户操作界面。研究结果表明,该铝型材焊接接头库的建立方便了车体建模,还可以允许用户按需求扩展焊接接头库,实现了系列化设计,提高了设计效率。 相似文献
16.
17.
Soran Hassanifard Mohammad Zehsaz Firooz Esmaeili 《Journal of Mechanical Science and Technology》2011,25(3):647-653
In the present study, the effects of spot weld arrangements in multi-spot welded joints on the fatigue behavior of the joints
are studied. Three different four-spot welded joints are considered: one-row four-spot parallel to the loading direction,
one-row four-spot perpendicular to the loading direction and two-row four-spot weld specimens. The experimental fatigue test
results reveal that the differences between the fatigue lives of three spot welded types in the low cycle regime are more
considerable than those in the high cycle regime. However, all kinds of spot weld specimens have similar fatigue strength
when approaching a million cycles. A non-linear finite element analysis is performed to obtain the relative stress gradients,
effective distances and notch strength reduction factors based on the volumetric approach. The work here shows that the volumetric
approach does a very good job in predicting the fatigue life of the multi-spot welded joints. 相似文献
18.
Mustafa Kemal Kulekci Aydin Şik Erdinç Kaluç 《The International Journal of Advanced Manufacturing Technology》2008,36(9-10):877-882
The objective of this study was to determine the effects of the tool pin diameter and tool rotation on the fatigue behaviour of friction stir welded (FSW) lap joints. FSW lap joints of AA 5754 aluminium alloy plates were produced by means of a conventional semiautomatic milling machine. Consequently, defect free FSW lap joints were produced on alloy plates at a constant traverse speed but with different tool pin diameter and tool rotation. Therefore, within this study, tool rotation and the tool pin diameter were accepted as variable parameters, while others held fixed. The results of the tests performed, indicate that an optimisation is required for the studied parameters, in order to obtain reasonable fatigue strength. An index, related to tool rotation, traverse speed, pin diameter, and pin height can be identified and used to select optimum parameters for FSW applications. 相似文献
19.
Bolin He Haipeng Deng Mingming Jiang Kang Wei Li Li 《The International Journal of Advanced Manufacturing Technology》2018,95(5-8):1571-1595
This paper presents bi-criteria formulation of a tolerance allocation model for an interchangeable assembly to simultaneously evolve suitable combination of manufacturing facility in multiple facility shaft-hole production environments of medium- and large-scale industries and tolerances to complement the need of customers. An Exhaustive Search Procedure is used to obtain the optimal solution for small and medium size problems and simulated annealing algorithm is used for large size problems. The usefulness of the Pareto front in manufacturing tolerance allocation decisions is demonstrated with three case study problems. The effect of process capability of shaft-hole assembly manufactured from alternative manufacturing machines and the optimality is analyzed in three cases to understand their criticality in decision-making. The models discussed in this paper could be useful for medium- and large-scale manufacturing industries, where there will be a variety of manufacturing facilities (specifications, capabilities, models, and types) for making both shaft-hole assembly and play a key role to meet the tolerance and cost requirements of different customers. This paper further discusses how this formulation and methodologies can be used for two hole and two shaft assemblies and multiple shaft-hole assemblies. Finally, the paper ends with highlighting directions of future research avenues in the shaft-hole assembly. 相似文献