共查询到19条相似文献,搜索用时 171 毫秒
1.
低匹配对接接头的“等承载”设计及拉伸疲劳行为 总被引:4,自引:0,他引:4
为提高高强钢低匹配接头的承载能力,以"等承载能力"(Equal load-carryingc apacity,ELCC)(即焊缝与母材承载能力相等)为原则,进行对接接头的形状参数设计。有限元计算表明,ELCC设计使对接接头焊缝区域(包括焊趾和焊根)应力应变显著降低,低强焊缝的承载能力提高。试验结果表明,ELCC对接接头强度可基本达到母材抗拉强度;在高应力区,ELCC对接接头疲劳强度与削平等匹配接头非常接近,在低应力区,随匹配比降低ELCC对接接头疲劳寿命有所降低;0.57屈服强度匹配比的ELCC对接接头对应1×107循环的疲劳强度较焊态等匹配对接接头提高约115%,可达到0.96匹配比削平对接接头的80%。ELCC设计克服低匹配接头承载能力低的不足,并且可在较大范围内选择匹配比而不必降低应用应力。 相似文献
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分别采用钨极氩弧焊(GTAW)和搅拌摩擦焊(FSW)对10mm厚5754铝合金进行双面同步焊接,对比研究了应力幅为162,135,117,108,99MPa时焊接接头的疲劳性能,并对其疲劳断裂机理进行了分析。结果表明:在指定应力幅下,5754铝合金GTAW接头的疲劳强度明显高于FSW接头的,在50%和95%存活率下,GTAW接头的疲劳强度特征值比FSW接头的分别提高了27%和30%,GTAW接头的疲劳性能优于FSW接头的;GTAW接头与FSW接头的疲劳断裂机理基本相同,疲劳裂纹均起源于接头熔合区的外表面,随着应力幅的降低,疲劳裂纹扩展区在断口中的占比增加,且同等应力幅下GTAW接头疲劳裂纹扩展区的占比高于FSW接头的;同等应力幅下GTAW接头的疲劳辉纹间距比FSW接头的小,GTAW接头的疲劳寿命长于FSW接头的。 相似文献
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通过2524-T3铝合金的搅拌摩擦焊接头疲劳性能对比试验,得到了母材、FSW对接接头、铆钉连接接头的疲劳S-N曲线。试验表明,搅拌摩擦焊的疲劳裂纹大多数起源于焊缝底部;2524-T3材料薄板的疲劳性能略好于厚板的疲劳性能;搅拌摩擦焊接头疲劳性能要明显好于铆接接头疲劳性能。拟合得到了各种不同厚度,不同应力比下的S-N曲线公式,为搅拌摩擦焊技术应用于飞机结构积累了相关数据。 相似文献
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AZ31B镁合金TIG焊焊接接头的疲劳性能 总被引:1,自引:1,他引:0
对8 mm厚AZ31B镁合金板及其三种TIG焊焊接接头的静载拉伸性能和疲劳性能进行试验研究。试验结果表明AZ31B镁合金母材的静载抗拉强度为245.50 MPa,TIG焊对接接头、纵向角接接头和非承载十字接头的静载抗拉强度分别为193.55 MPa、229.89 MPa、227.39 MPa。脉动循环(r = 0)疲劳试验表明,在2×106循环次数下,AZ31B镁合金母材的疲劳强度为57.81 MPa,为其静载抗拉强度的23.5%。相同循环次数下,AZ31B镁合金TIG焊对接接头、纵向角接接头和非承载十字接头的疲劳强度为24.60 MPa、20.14 MPa、17.25 MPa,分别为母材疲劳强度的42.6 %、34.8 %和29.8 %。按照国际焊接学会的规范,发现镁合金焊接接头的疲劳级别FAT仅为相应铝合金接头疲劳级别FAT的一半。由此看来,疲劳性能是影响镁合金在承受动态载荷结构中应用的主要因素之一。 相似文献
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针对具有吻接缺陷的5083铝合金板搅拌摩擦焊(FSW)对接接头试件,探索了吻接缺陷对搅拌摩擦焊对接接头疲劳强度的影响.使用维氏显微硬度仪测量了试件接头焊缝横截面硬度分布,测试结果显示,硬度值分布大致呈W趋势.采用MTS809疲劳测试机对试件进行疲劳测试,得到了不同吻接深度拉伸式样的名义应力-寿命关系.对疲劳断口进行SEM扫描并测量了接头吻接缺陷深度,发现疲劳裂纹均起源于吻接缺陷区域.通过有限元软件ABAQUS对不同吻接深度试件进行了应力应变分析,分别采用缺口应力法和局部应力应变法对试件进行了疲劳寿命预测.预测结果表明,缺口应力法在低周疲劳预测时效果较好. 相似文献
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为确定火箭贮箱搅拌摩擦焊(FSW)焊接接头疲劳寿命,完成对贮箱结构的疲劳分析,对2195铝锂合金母材标准试件与搅拌摩擦焊焊接接头标准试验件进行静力试验与常幅疲劳试验,得出母材与FSW焊接接头的拉伸强度等力学性能参数,同时绘制其S-N曲线。在试验数据基础上,应用ABAQUS软件对贮箱进行静力分析,联合NCODE软件估算贮箱模型在给定工况载荷下的疲劳寿命。结果表明:应力最严重位置为筒段焊缝处,最先破坏位置发生在筒段横竖焊缝交接处。在疲劳寿命分析的基础上应用ABAQUS-FRANC3D软件联合仿真,在焊缝破坏位置处插入角裂纹,模拟三维裂纹扩展,当裂纹扩展为穿透裂纹时,计算终止。计算了三维表面裂纹的应力强度因子和裂纹扩展寿命,为贮箱损伤容限提供了评估思路。 相似文献
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采用单面两道焊方式对8 mm厚G20Mn5铸钢板进行熔化极活性气体保护电弧(MAG)对接焊,研究了接头的显微组织、硬度、拉伸性能、疲劳性能。结果表明:接头表面成形良好,无明显的焊接缺陷;接头由母材、热影响区、焊缝组成,其中热影响区可分为不完全正火区、正火区和过热区;由母材到焊缝中心,接头硬度整体呈先升高后降低的趋势,熔合处的硬度最高,达到70HRB左右,焊缝的硬度为55~60HRB,略高于母材的;接头的抗拉强度明显高于母材的,而断后伸长率低于母材的;接头的高周疲劳强度与母材的相当,且断裂位置均位于热影响区。该接头的性能满足设计要求。 相似文献
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Daxin Ren Liming Liu Yongfei Li 《The International Journal of Advanced Manufacturing Technology》2012,61(1-4):195-204
This paper presents the research on weldability of magnesium alloy AZ61 sheets by overlap laser welding, adhesive bonding, and laser seam weld bonding processes. Microstructures and mechanical properties of the joints are investigated. In overlap laser welding, the joint fractures at the interface between the sheets and maximum shear strength can reach 85% of that of the base metal. Off-center moment during tensile shear test can lead to the strength loss, while the weld edge can also influence the strength as a cracking source. Adhesive bonded joint can offer high tensile shear failure force but low peel strength. Laser weld bonded joint offers higher tensile shear failure force than either laser welded joint or adhesive bonded joint does, and the improved failure load is due to combined contribution of the weld seam and the adhesive. The weld seam can block the adhesive crack propagation, and the adhesive improves the stress distribution, so they can offer a synergistic effect. 相似文献
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A study on mechanical characteristics of the friction stir welded A6005-T5 extrusion 总被引:1,自引:0,他引:1
Weon-Kyong Kim Si-Tae Won Byeong-Choon Goo 《International Journal of Precision Engineering and Manufacturing》2010,11(6):931-936
In this paper, A6005-T5 extruded aluminum alloy sheets which are used for floor, roof or wall panels of railroad vehicles
were welded by the friction stir welding (FSW) and gas metal arc welding (GMAW) techniques. The mechanical characteristics
including the tensile strength, micro-hardness and fatigue strength of the FSW joint were compared to those of the base metal
and GMAW joints. In order to determine the relationship between the welding variables of FSW and the mechanical characteristics
of the joint, the response function was derived using the least square method and the sensitivity analysis was performed.
The rotational speed, welding speed and tilting angle of the welding tool were chosen as design variables. On the basis of
the Plackett-Burman design table, eight different FSW experiments were done, and then the effects of design variables on the
mechanical characteristics of the FSW joint were analyzed. The result showed that the welding speed has a most significant
effect on the tensile and fatigue strength. In the case of the micro-hardness, the effect of the tilting angle was the biggest. 相似文献
14.
A. K. Lakshminarayanan V. Balasubramanian K. Elangovan 《The International Journal of Advanced Manufacturing Technology》2009,40(3-4):286-296
The present investigation is aimed at to study the effect of welding processes such as GTAW, GMAW and FSW on mechanical properties of AA6061 aluminium alloy. The preferred welding processes of these alloys are frequently gas tungsten arc welding (GTAW) and gas metal arc welding (GMAW) due to their comparatively easier applicability and better economy. In this alloy, the weld fusion zones typically exhibit coarse columnar grains because of the prevailing thermal conditions during weld metal solidification. This often causes inferior weld mechanical properties and poor resistance to hot cracking. Friction stir welding (FSW) is a solid phase welding technique developed primarily for welding metals and alloys that heretofore had been difficult to weld using more traditional fusion techniques. Rolled plates of 6 mm thickness have been used as the base material for preparing single pass butt welded joints. The filler metal used for joining the plates is AA4043 (Al-5Si (wt%)) grade aluminium alloy. In the present work, tensile properties, micro hardness, microstructure and fracture surface morphology of the GMAW, GTAW and FSW joints have been evaluated, and the results are compared. From this investigation, it is found that FSW joints of AA6061 aluminium alloy showed superior mechanical properties compared with GTAW and GMAW joints, and this is mainly due to the formation of very fine, equiaxed microstructure in the weld zone. 相似文献
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Effect of Lack of Penetration on the fatigue strength of high strength steel butt weld 总被引:1,自引:0,他引:1
Sungho Kim Keunchan Jin Wan Sung Soowoo Nam 《Journal of Mechanical Science and Technology》1994,8(2):191-197
Fatigue tests are performed to evaluate the fatigue strength of high strength steel containing partial penetration butt weld and full penetration butt weld. The influence of the unwelded ligament (Lack of Penetration) in the partial penetration welds on the fatigue life is analyzed for various LOP sizes. For full penetration welds, the fatigue crack initiated at the weld toe and propagated to the HAZ. For partial penetration welds, however, the fatigue cracks initiated at the LOP section and propagated to the weld metal (or weld toe) for the considered LOP sizes (from 2mm to 4mm) reducing the fatigue strength. Consequently, the increament of the LOP size yield in the fatigue life degradation by some extent. 相似文献
17.
Long Chen Longzao Zhou Chao Tang Wei Huang Chunming Wang Xiyuan Hu Jun Wang Fei Yan Xuefang Wang Zhengguang Jiang Xinyu Shao 《The International Journal of Advanced Manufacturing Technology》2014,73(9-12):1695-1704
This paper describes a study on laser butt welding of 4 and 2 mm SUS301L stainless steel and a detailed analysis of welding joints. The gap tolerance of butt joint was also studied with optimized process parameters. The electrolytic etching in 10 % oxalate solution was used to test the intergranular corrosion of the 4 mm SUS301L welded joint. Fatigue property of the 2 mm SUS301L welded joint was tested under the conditional cycle times of 1?×?107. Using optical microscopy, the changes of metallurgical microstructure in the weld zone of 4 mm SUS301L were also studied. It has been found that laser butt welding of 4 mm SUS301L is able to achieve sound metallurgical morphology and high strength weld joint when the butt gap is within certain tolerance. The weld joint also has good resistance to intergranular corrosion and has a fatigue limit of 310 MPa. 相似文献
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对航空用3 mm厚的带有包铝层的7B04-O铝合金板材进行搅拌摩擦焊接(Friction stir welding,FSW),研究固溶处理对搅拌摩擦焊接接头的微观组织和力学性能的影响。结果表明,当转速为800 r/min、焊接速度为200 mm/min、焊接工具轴肩直径为12 mm时,可得到表面美观、致密无缺陷的搅拌摩擦焊接接头。焊核区发生动态再结晶,形成细小的等轴晶。经固溶处理后,焊核的上部及底部晶粒都发生了异常长大,而中部区域晶粒仍然为细小的等轴晶组织。焊态接头的拉伸试样断裂在母材位置,抗拉强度达到199 MPa,与退火态母材抗拉强度相当,断后伸长率达到12%。在新淬火状态下,接头的抗拉强度为310 MPa,为相同热处理母材的91.4%,断后伸长率为11.2%,试样断裂在焊核区,呈不完全的韧性断裂。 相似文献