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镁合金拼焊板拉深成形焊缝移动规律 总被引:1,自引:0,他引:1
采用有限元数值模拟软件对镁合金拼焊板拉深成形时焊缝移动规律进行了数值分析,建立了镁合金拼焊板筒形件拉深成形有限元模型.对AZ31与AZ80镁合金拼焊板拉深成形进行了数值模拟,分析了压边力及变形温度对焊缝移动规律的影响,得到了筒形件底部及侧壁法兰处焊缝的移动规律.结果表明,筒形件底部焊缝向AZ80侧移动,法兰及侧壁处向AZ31侧移动.模拟结果与试验结果吻合较好,镁合金拼焊板拉深成形时焊缝移动可以通过非均匀压边力或非均匀温度场来控制. 相似文献
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对由激光拼焊板制成的整体侧围内板进行了基于Dynaform成形软件的冲压成形模拟及参数的优化,分析了零件在冲压成形过程中的金属流动及应力应变分布规律。根据冲压后的模拟结果,进行参数优化,通过改变压边力、改进等效拉深筋等措施,抑制了成形中焊缝的移动,消除了起皱、破裂等成形缺陷。实践证明,产品质量与数值模拟结果吻合良好。 相似文献
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分析了汽车B柱拼焊板成形过程的工艺方案.利用有限元分析软件Dynaform对其成形过程进行了数值模拟.对成形中出现的破裂、起皱和焊缝移动等现象进行了研究.分析了产生缺陷的原因,提出工艺优化措施,最后通过模拟得到了较好的结果,并用生产零件验证了B柱拼焊板拉深成形工艺的可行性. 相似文献
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前地板属于扁平拼焊板汽车覆盖件,在拉深成形后出现零件刚性不足、焊缝移动等质量问题.针对这些质量问题,在拉深型面中采用拉深槛以提高零件成形的刚度,并通过有限元分析软件Dynaform对其拉深成形中出现的破裂、焊缝移动等现象进行研究,分析产生缺陷的原因,提出工艺改进措施,如增加加强筋和进行焊缝移动补偿.模拟结果表明,优化的拉深成形结果良好,加强筋的设置不仅增加了零件的刚性,而且能一定程度抑制焊缝的移动,同时焊缝反向补偿的方法对焊缝移动的进一步控制起到了有效作用.最后通过实际生产得到了合格的零件,验证了优化结果的可靠性. 相似文献
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分析了控制焊缝移动的拼焊板薄厚两侧所需的压边力关系式,并据此提出了变压边力控制方案。通过数值模拟对比分析了不同方案的冲压结果,验证了:减少厚侧压边力可有效的降低焊缝向薄侧的移动量,从而降低薄侧材料应力集中,改善应力状态,大大提高了拼焊板的成形性能。 相似文献
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《机械制造文摘:焊接分册》2009,(6):3-3
差厚拼焊板盒形件成形影响因素及焊缝移动规律
研究了拼焊板厚度组合、强度组合及成形过程中焊缝移动问题。通过数值模拟技术,建立了有拉延筋和没有拉延筋情况下的有限元模型,分析了不同板厚组合和不同强度组合对拼焊板成形性的影响,同时分析了拉延筋对焊缝移动量的影响,揭示这些因素影响成形性能的一般规律,提出一种减少焊缝移动的方法。研究结果表明:差厚板薄板与厚板的厚度比值取不低于0.5时,有利于成形极限的提高; 相似文献
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ABSTRACTTo understand the cause of compressive residual stress in welded joints, we analysed by numerical analysis the effect of welding pass sequence using low transformation temperature (LTT) welding materials on residual stress around the weld toe of boxing fillet welded joints. It was determined by numerical analysis that the produced compressive residual stress and the influence of the stiffeners are reduced in the equivalent position of the weld toe in a fillet welded joint because of the influence on the behaviour of the stiffener in the weld being due to residual stress distribution around the weld toe. The residual stress reduction method of extending the length of the welded bead and releasing the weld toe from the stiffener, similar to the concept of discarding a bead to reduce tensile residual stress, was effective in fillet welded joints. Numerical analysis of the relationship between residual stress around the weld toe and width of the weld bead in the bead-on-plate welding model clarified that compressive residual stress can be introduced around the weld toe by having a wide width weld bead. In addition, a fully penetrated welded joint was very effective for causing compressive residual stress around the weld toe. 相似文献
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《Science & Technology of Welding & Joining》2013,18(8):662-668
AbstractThe forming behaviour of tailor welded blanks (TWBs) has been widely studied since its development. In the numerical simulation studies, the TWBs are modelled as blanks composed of two different materials, and often, the presence of the weld bead is neglected in its finite element discretisation. In the present work, the influence of the weld bead shape on the formability of friction stir welded TWBs, is analysed. Several finite element meshes were constructed in order to represent different weld bead geometries and numerical simulations of the cylindrical cup drawing were performed. Strong influence of the weld bead shape on the formability of the TWBs was observed when the weld was in overmatch relatively to the base material, and little influence when the weld was in undermatch condition. Comparison of the numerical results with experimental ones shows that the numerical analysis is able to preview the formability of the TWBs. 相似文献
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残余应力是导致细晶粒钢激光深熔焊时裂纹产生的主要机理之一,对焊接质量有较大影响. 文中基于细晶粒钢激光深熔焊实际焊缝金相组织建立热源模型,采用PDA-5500S岛津光谱元素分析仪提取细晶粒钢化学成分,基于吉布斯函数建立细晶粒钢的温度与流变应力耦合本构关系;同时,通过不同焊接参数下焊缝截面试验数据,在热源模型中设置跟踪点,获取焊缝中实时残余应力,研究不同温度下实时残余应力与细晶粒钢流变应力对焊接缺陷的影响. 结果表明,在相同温度下当实时残余应力高于材料流变应力时,焊缝内产生裂纹;合理提高焊接速度,可降低细晶粒钢焊缝实时残余应力,提高激光深熔焊接质量. 相似文献
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采用力学测试、组织分析、扫描电镜和能谱分析的方法,研究了X90高强度管线钢预精焊的焊接裂纹形貌,并分析了裂纹形成原因.结果表明,X90螺旋焊钢管内焊缝上的横向裂纹为冷裂纹,裂纹在焊缝组织中呈穿晶扩展或沿晶界扩展.X90含有较多的Mn,Cr,Mo,Ni,Cu等合金元素,强度高,导致内焊缝的焊接残余应力高于裂纹的临界应力.内焊道维氏硬度比外焊道的高,且焊缝两侧的硬度分布极不对称,造成了内焊道附近的应力集中和分布不平衡.内外焊缝重合区域的扩散氢不易逸出,其含量较高,在气孔、夹渣等“陷阱”处聚集,导致裂纹产生和断口上大量氢白点形成.焊缝一次结晶所形成的连续细长的树枝晶晶界为裂纹扩展提供了“通道”. 相似文献
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In this study, a three-dimensional (3D) finite element model is developed to investigate thermally induced stress field during hybrid laser–gas tungsten arc welding (GTAW) process. In the hybrid welding case, we focus on the GTAW process sharing common molten pool with laser beam and playing an augment role in the hybrid welding system. An experiment-based thermal analysis is performed to obtain the temperature history, which then is applied to the mechanical (stress) analysis. A modified material model is used to consider the influence of face-to-face contact between the top and bottom metal sheets in the thermo-mechanical analysis of welding lap joints. Results show that the normal stress components prevail in the weld zone during hybrid welding process, and maximum thermal stress exceeding the yield point of material exists at the heat affected zone (HAZ) near the weld pool. Increasing the welding speed causes the penetration and width of weld bead to decrease, and the thermal stress concentration at the welded joint is also reduced accordingly. After welding and cooling down, longitudinal tensile stress (SZ) and transverse compressive stress (SX) are retained in the formed weld, and the higher longitudinal compressive stress exists around the weld bead. In addition, a series of experiments are performed to validate the numerical results, and a qualitative agreement is achieved. Compared to the welded joint obtained by GTAW and laser welding alone, the residual stress concentration in the weld joint obtained by hybrid laser–GTAW is the minimal one. 相似文献
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基于Dynaform的激光拼焊板成形性能数值模拟研究 总被引:1,自引:1,他引:0
为了解决同种材料、等厚度激光拼焊板在数值模拟研究中如何建立准确的焊缝模型这一难题,通过显微硬度试验测量拼焊板焊接接头焊缝区和热影响区的硬度值,并对这些数据进行分析和计算,得到两个区域的材料力学性能参数,建立焊缝模型,并采用有限元模拟软件Dynaform 5.5对建立的焊缝模型进行数值模拟.通过模拟和试验结果的对比,验证... 相似文献
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Denis Thibault Philippe Bocher Marc Thomas 《Journal of Materials Processing Technology》2009,209(4):2195-2202
The objectives of the present study were to characterize the distribution of residual stress and the microstructure changes induced by welding in the heat-affected zone (HAZ) of 13%Cr–4%Ni used in hydraulic turbine fabrication to deduce best practices. To characterize residual stress after welding, hole-drilling, X-ray diffraction (XRD) and the contour method were used on a FCAW 6 passes UNS W41036 (410NiMo) weld deposited on UNS S41500 (13%Cr–4%Ni) stainless steel; the results were put side to side with the weld microstructure and hardness to assess their criticality. Transverse compression was found in and around the last bead of the weld by XRD and hole-drilling. Longitudinal compression stress was found in and around the last bead while longitudinal tension was found near the low-temperature HAZ. The contour method showed that despite high compression in the last bead, high longitudinal tension exists in the rest of the weld and just below the weld. The superposition of both residual stress distribution and results from microstructural characterization shows that in multipass welding of 13%Cr–4%Ni martensitic stainless steel, cracking susceptibility is higher in the weld than in the HAZ, let it be fatigue cracking, environment-assisted cracking or cold cracking during welding. Post-weld heat treatment proved to be very efficient in lowering residual tension found in the first bead and in lowering the hardness of the weld. These results underline the importance of following proper procedures when welding these steels; this being even more true when the assembly is loaded in fatigue. 相似文献