共查询到20条相似文献,搜索用时 203 毫秒
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针对薄板铝合金激光焊接过程,采用有限体积法开展熔池流动研究.建立了三维焊接熔池流动数学模型,并采用高斯旋转体热源表征激光束的热作用.在考虑与不考虑表面张力作用下,分别计算获得了焊接温度场、熔池流场和熔池形貌.基于计算结果,分析了温度场云纹图、熔池焊接热循环曲线、熔池速度场分布多视图.最后进行相同参数下的激光焊接试验,基于观察获得的焊接接头形貌,综合分析了模拟结果和试验结果.结果表明,所建立的模型和模拟方法是合理可行的.同时考虑Marangoni对流作用所计算得到的熔池和焊缝几何形状更加接近实际焊接接头. 相似文献
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针对管线钢焊接,考虑了材料热物理性能参数、相变潜热与温度的非线性关系,建立了焊接过程的数学模型和物理模型。利用ANSYS软件的APDL语言编写程序,实现了在移动热源载荷下的焊接有限元计算,分析对比了不同焊接工艺参数对焊接温度场的影响程度。 相似文献
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针对单边开坡口的非对称角根焊中熔透不稳定、成形质量差的问题,对其温度场及熔池成形规律进行分析从而优化焊接参数的选取,改善成形质量.考虑温度、对流、辐射和相变潜热对材料物理性能的影响,利用有限元分析软件建立了低碳钢非对称角焊缝有限元模型,并进行仿真计算.对比讨论了不同结构情况下焊接电流对温度场的影响,重点分析了非对称角焊接参数对背部熔宽的影响.结果表明,非对称角焊缝温度分布不均匀,背部熔宽对电流的变化十分敏感,焊接电流大小对熔池形状影响较大.通过试验得到三组熔透情况不同的焊缝,其热影响区形状尺寸与仿真结果吻合良好,从而验证了理论分析的有效性. 相似文献
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《Science & Technology of Welding & Joining》2013,18(5):377-384
AbstractThe present work reports on a two-dimensional axisymmetric finite element analysis of heat flow during laser spot welding, taking into account the temperature dependence of the physical properties and latent heat of transformations. An analysis based on conduction heat transfer alone, but using the 'double ellipsoidal' representation of the laser beam, seems to be sufficient to estimate the transition to keyhole formation during laser spot welding, although the 'double ellipsoidal' representation requires an a priori knowledge of the expected weld pool dimensions. Transient temperature isotherms and the weld pool dimensions are predicted using the model; the latter are found to compare well with measurements of weld bead dimensions. The results show that the keyhole mode is stimulated using either a high laser power and low on-time or a low laser power and high on-time. The outcomes are found to be sensitive to the assumed absorptivity and the assumed weld pool depth used to define the 'double ellipsoidal' heat source. 相似文献
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《Science & Technology of Welding & Joining》2013,18(5):407-414
AbstractA three-dimensional model has been developed to study turbulent fluid flow and heat transfer in a gas metal arc weld pool. The phase change process during melting and solidification is modelled using the enthalpy–porosity technique. Mass and energy transports by droplet transfer are considered through a thermal analysis of the electrode. The droplet heat addition into the molten pool is considered to be in the form of a volumetric heat source distributed in an imaginary cylindrical cavity within the weld pool ('cavity' model). A two-equation k-ε model capable of addressing turbulent weld pool convection, taking into account the morphology of the phase change, is presented. The weld pool dynamics and geometry (shape and size) in a moving gas metal arc welding (GMAW) process are studied and the effects of enhanced diffusivities on the turbulent weld pool are discussed. The predicted weld pool geometry using laminar and turbulent models is also compared with corresponding experimental post-weld sections. 相似文献
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建立了背反射增效激光焊焊接熔池流动中气相区、液相区和固相区的统一模型,在模型中考虑了等离子体/蒸气云和小孔吸收机制,综合了表面张力、热浮力和重力的作用. 基于数值计算得到了熔池的三相匙孔相变以及流场,重点分析了表面张力对熔池流动和传热的影响. 此外,通过钛合金薄板的背反射增效激光焊接试验对模型进行了验证. 结果表明,匙孔引发等离子体/蒸气云与背面垫板诱发羽辉的耦合作用,是X形焊缝熔池形貌形成的主要原因;同时,表面张力是形成背反射增效激光焊接熔池内“椭圆回流环”的主要驱动力. 相似文献
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基于FLUENT软件,建立了适用、高效的激光+GMAW复合焊流体流动数值分析模型. 将电弧热输入视为双椭球热源模型,采用基于小孔尺寸的锥体热源模型描述激光热流分布;将金属填充过程视为液态金属从熔池上部边界以一定速度流入熔池过程,并通过对液态金属流速施加时间脉冲函数,模拟熔滴的过渡频率;模型简化了小孔的计算过程,主要考虑熔池中存在的弯曲小孔对流体的影响. 利用FLUENT软件,对激光+GMAW复合热源焊熔池流体流动及小孔形态进行了模拟计算和分析. 结果表明,模型能够合理反映小孔及复合焊流体流动模式的主要特征,且提高了计算效率. 相似文献
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提出了一种三维瞬态小孔与瞬态熔池相结合的激光小孔焊接耦合数学模型.该模型综合考虑了多重反射菲尼尔吸收、小孔界面上的间断边界条件、金属蒸气/等离子体的辐射传热、Marangoni力、固-液相间的摩擦力、浮力、粘性力、蒸发潜热、熔化/凝固潜热,以及热传导、对流、辐射等多种因素对激光小孔焊接过程的耦合作用.采用水平集方法和快速扫描方法对小孔演化方程进行求解,得到了三维瞬态小孔形貌;并采用SOLA方法求解了瞬态熔池的三维传热和流动过程.结果表明,该模型能够较好地模拟激光小孔焊接中瞬态小孔和熔池的动态演化行为. 相似文献
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激光+GMAW复合热源焊接过程热-力耦合数值分析 总被引:3,自引:2,他引:1
从宏观的焊接热过程出发,根据激光+GMAW复合热源焊接的特点,提出了适用于复合热源焊接的“双椭球体+峰值递增圆柱体”组合式体积热源分布模式;建立了激光+GMAW复合热源焊接过程的有限元模型,数值计算了焊接温度场和焊缝横截面的形状尺寸,计算结果与试验结果吻合良好,证明了组合式体积热源模型的合理性和适用性. 采用焊接温度场的计算结果,进一步对复合热源焊接和GMAW的焊接变形和残余应力进行了数值模拟和对比分析. 结果表明,在焊缝熔深基本相同的情况下,复合热源焊接的焊接热输入、焊缝熔宽、焊接变形和高应力区域范围等均比GMAW小. 研究结果印证了激光+GMAW复合热源焊接工艺的优越性,并为焊接工艺参数的优化提供了基础理论数据. 相似文献
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《Journal of Materials Processing Technology》2014,214(2):428-435
The finite-element thermal analysis of the welding process of a titanium-alloy tank with an elastomeric diaphragm is described. The analysis takes into account the latent heat due to phase changes, the dependence of the material properties with temperature and the effects of the convection in the weld pool. The model is calibrated and validated by comparing its predictions with experimental results from the welding of AISI 304 specimens. The comparison between the model and the experimental results is made in terms of the temperature fields and the dimensions of the weld molten pool. The time evolution of the temperature in the experiments is monitored using thermocouples and a thermographic camera. The molten pool dimensions are measured via macro etching. The girth weld of the tank is analyzed for various hypotheses for the efficiency of the contact heat conduction between the hemispheres and the diaphragm-retaining ring. The results show the convenience to include a heat sink to the welding setup in order to guarantee the thermal integrity of the elastomeric diaphragm. 相似文献
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研究了两种焊丝熔化方法(电弧预熔丝激光焊、激光填丝焊)激光焊接过程对匙孔稳定性以及焊缝成形的影响,进一步研究了焊丝熔化方法对焊接接头质量的影响,并对比分析了两种焊丝熔化方式对焊接速度的适应性. 结果表明,电弧预熔丝激光焊过程中,熔池表面匙孔开口尺寸变化不大,匙孔较为稳定;激光填丝焊方法由于熔化的液态金属距离匙孔边缘很近,焊接过程中熔池表面匙孔开口尺寸变化较大,而且容易出现熔池表面匙孔的闭合. 与激光填丝焊相比,电弧预熔丝激光焊熔化的焊丝端部可以沿熔池边缘流入,与匙孔边缘的距离较远,匙孔稳定性较好,焊缝气孔数量较少. 当焊接速度为8 m/min时,电弧预熔丝激光焊的焊缝成形良好;而激光填丝焊焊缝背面成形不连续,并且出现了未焊透的缺陷. 相似文献