共查询到19条相似文献,搜索用时 453 毫秒
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焊件在快速加热和冷却过程中温度场的正确描述是焊后接头力学性能分析的前提条件。材料物理性能参数的非线性以及冷却过程中伴随相变产生的相变潜热均会影响温度场的分布。焊接温度场的准确计算必须建立起准确的热传递和相变计算的数学模型以及符合焊接生产实际的物理模型。文中采用Goldak热源分布模型,其表面上热量是按高斯分布的函数,内部是双椭球函数来表示其分布,并应用SYSWELD软件的校正工具根据具体的焊接工艺和条件对热源进行校正;考虑了各相的热物理性能参数及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,实现了热-冶金的耦合分析计算,并以低合金结构钢的堆焊为例,对其温度场进行了三维动态模拟。 相似文献
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利用有限元方法对挖掘机动臂平板对接焊温度场进行了分析,采用Goldak椭球热源模型,应用DFLUX子程序定义热源模型的位置、大小、热输入以及焊接速度等参数来模拟瞬态温度场的分布及其变化,在此基础上通过改变焊接热输入、热源模型参数和焊接速度来分析其对温度场分布的影响规律.研究结果表明,由于焊接热源具有集中移动的特点,焊接热源模型参数以及焊接速度对焊缝区和热影响区的温度分布影响比较明显,热输入的变化与最高温度的变化大致呈线性关系.运用有限元法,选取Goldak椭球热源模型通过DFLUX子程序可有效进行挖掘机动臂平板焊接的数值模拟. 相似文献
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薄板TIG对接焊温度场的有限元模拟 总被引:3,自引:1,他引:3
焊件中的温度场分布反映了复杂的焊接热过程,是研究焊接变形、焊后残余应力等状况的基础。焊接数值模拟技术的出现,为焊接技术的深入发展创造了有力的条件。针对低碳钢薄板件TIG对接焊时,应用双椭圆分布热源模型,建立了TIG对接焊三维温度场有限元数值分析模型,将有限元解同实验结果进行了比较,两者基本吻合,表明了该分析模型的有效性,并以此有限元模型为基础,分析了两焊板间存在间隙和焊枪偏离焊缝中心这一实际情形下,温度场分布的不均匀性。 相似文献
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针对奥氏体不锈钢0Crl8Ni9的TIG焊接过程,建立了相应的数学模型和物理模型,并基于ANSYS平台进行有限元计算,分析了双椭球热源模型各参数对熔合区、热影响区分布和边界走向以及焊接温度场的影响规律。结果表明,在其他条件一定的情况下,热源宽度参数b主要影响熔合区和热影响区的宽度尺寸,热源深度参数c主要影响熔合区和热影响区的深度尺寸。研究还发现,熔合区的温度场分布和温度峰值对热源模型参数的变化较为敏感。 相似文献
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钽薄板TIG氦弧焊热过程的数值分析 总被引:1,自引:0,他引:1
针对钽薄板氦弧焊接的特点,基于有限元分析软件ANSYS,对钽薄板TIG氦弧焊接的温度场进行三维数值动态模拟,并将计算量控制在可接受的范围内。建模时采用实体单元和表面单元结合,并采用焊缝处细密、远离焊缝处粗略的不均匀网格,热载荷施加过程中采取了一系列非线性措施,分析了焊接结束后温度场在工件上的分布规律及冷却时间对工件温度场分布的影响,并据此提出了提高钽薄板TIG氦弧焊接接头质量的方案。计算结果表明熔池的尺寸随焊接时间的变化较为明显。计算所得熔池大小与实验结果基本吻合。 相似文献
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S. Elangovan K. Anand K. Prakasan 《The International Journal of Advanced Manufacturing Technology》2012,63(5-8):561-572
This paper focuses on the development of an effective methodology to determine the optimum welding conditions that maximize the strength of joints produced by ultrasonic welding using response surface methodology (RSM) coupled with genetic algorithm (GA). RSM is utilized to create an efficient analytical model for welding strength in terms of welding parameters namely pressure, weld time, and amplitude. Experiments were conducted as per central composite design of experiments for spot and seam welding of 0.3- and 0.4-mm-thick Al specimens. An effective second-order response surface model is developed utilizing experimental measurements. Response surface model is further interfaced with GA to optimize the welding conditions for desired weld strength. Optimum welding conditions produced from GA are verified with experimental results and are found to be in good agreement. 相似文献
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Chen YanbinLi LiqunFeng XiaosongFang JunfeiState Key Laboratory of AdvancedWelding Production Technology Harbin Institute of Technology Harbin China 《机械工程学报(英文版)》2004,17(4):511-514
The welding mechanism of laser-TIG hybrid welding process is analyzed. With the variation of arc current, the welding process is divided into two patterns: deep-penetration welding and heat conductive welding. The heat flow model of hybrid welding is presented. As to deep-penetration welding, the heat source includes a surface heat flux and a volume heat flux. The heat source of heat conductive welding is composed of two Gaussian distribute surface heat sources. With this heat source model, a temperature field is calculated. The finite element code MARC is employed for this purpose. The calculation results show a good agreement with the experimental data. 相似文献
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W. H. Li S. B. Chen B. Wang 《The International Journal of Advanced Manufacturing Technology》2008,36(11-12):1072-1079
Modeling is an important step both for quality and shaping control of the arc welding process. Current modeling methods have made great advances in the field of arc welding, however they all posses certain limitations. It is due to these limitations that we created the variable precision rough set (VPRS) based modeling method. The VPRS modeling has been shown to be both a more efficient and reliable modeling method for the arc welding process due to its ability to account for the character of the welding media. The method was used to produce a dynamic predictive model for pulsed gas tungsten arc welding (GTAW). Results showed that the VPRS modeling method was able to sufficiently acquire knowledge during welding practices. In addition, comparison of VPRS model with classic rough set model and BP neural network model showed that VPRS model was more stable and could predict the unseen data better than classic RS model. Moreover, the VPRS model owns similar precision with neural network model, but has better understandability. 相似文献
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Welding parameters optimization for economic design using neural approximation and genetic algorithm
Hsien-Yu Tseng 《The International Journal of Advanced Manufacturing Technology》2006,27(9-10):897-901
Welding is a basic manufacturing process for making components or assemblies. Recent welding economics research has focused on developing the reliable machinery database to ensure optimum production. It is an important issue, especially for the expensive equipment and the high quality preference in welding. An integrated approach is proposed to address the welding economic design problem. The integrated approach applies general regression neural network to approximate the relationship between welding parameters (welding current, electrode force, welding time, and sheet thickness) and the failure load. Analytical formula can be generated from the trained general regression neural network, and the mathematical model for the economic welding design can be constructed. An optimization method based on genetic algorithms is then applied to resolve the mathematical model and to select the optimum welding parameters. These parameters are used to obtain the preferred welding quality at the least possible cost. 相似文献
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Adaptive volumetric heat source models for laser beam and laser + pulsed GMAW hybrid welding processes 总被引:1,自引:1,他引:0
G. X. Xu Chuan Song Wu G. L. Qin X. Y. Wang S. Y. Lin 《The International Journal of Advanced Manufacturing Technology》2011,57(1-4):245-255
Laser + pulsed gas metal arc welding (GMAW) hybrid welding process is an attractive joining technology in industry due to its synergy of the two processes. It is of great significance to conduct fundamental investigations involving mathematical modeling and understanding of the hybrid welding process. In this study, an adaptive heat source model is first developed for laser beam welding. Through combining the ray-tracing method with the keyhole profile determination technique based on the local energy balance, the keyhole shape and size are calculated and correlated to the distribution parameters of the volumetric heat source model. Then, thermal action characteristics in laser + pulsed GMAW hybrid welding are considered from viewpoint of macro-heat transfer, and a combined volumetric heat source model for hybrid welding is developed to take consideration of heat input from laser, pulsed gas metal arc, and overheated droplets. Numerical analysis of thermal conduction in hybrid welding is conducted. The shape and size of fusion zone and weld dimension in the quasi-steady state are calculated for various hybrid welding conditions, which have a fair agreement with the experimental results. 相似文献
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铝合金LB-VPPA复合焊接热源模型 总被引:1,自引:0,他引:1
激光-变极性等离子弧(Laser beam-variable polarity plasma arc,LB-VPPA)属双高能束新型复合焊接热源。采用Y4-S2型高速摄像检测了LB-VPPA复合焊接热源形态,在理论分析复合热源产热机理的基础上,利用Fortran语言对SYSWELD软件热源模型进行二次开发,建立能够实现正、反极性循环加载的LB-VPPA复合焊接热源模型。经与实际焊接熔池形状对比研究发现,熔池上部采用双椭球体热源,下部采用三维锥体热源,同时在小孔根部植入圆柱体热源的组合式热源模型与实际LB-VPPA复合焊接热源吻合。从模拟6 mm厚7A52铝合金板的VPPA焊和LB-VPPA复合焊接温度场分布结果发现,LB-VPPA复合焊能量更为集中,可以在平焊位置下实现穿孔型焊接。经实际焊接工艺试验验证了上述模拟结果的准确性。因此建立精确的LB-VPPA复合焊接热源模型对开展厚板铝合金LB-VPPA复合高效焊接提供强有力的理论支持。 相似文献
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Expandable profile liner(EPL) is a promising new oil well casing cementing technique, and welding is a major EPLs connection technology. Connection of EPL is still in the stage of manual welding so far, automatic welding technology is a hotspot of EPL which is one of the key technologies to be solved. A robot for automatic welding of"8" type EPL is studied. Four quadrants of mathematical equations of the 8-shaped cross-section track of EPL, consisting of multiple arcs, are established. Mechanism program for complex cross-section welding of EPL based on angle detection is proposed according to characteristics of small size, small valleys, and large forming errors, etc. A welding velocity vector control model is established by linkage control of a welding vehicle, a small driven actuator, and a height tracking mechanism. A constant speed control model based on an angle and symmetrical analysis model of rectangular coordinate system for EPL is built. Constraint conditions of constant speed control between each section are analyzed with 4 sections in first quadrant as an example, and cooperation work mechanism of the welding vehicle and the small tracking actuator is established based on pressure detection. The constant speed control model using angle self-test can be used to avoid the need for a precise mathematical model for tracking control and to adapt manufacture and installation deviation of EPL workpiece. The model is able to solve constant speed and trajectory tracking problems of EPL cross-section welding. EPL seams welded by the studied robot are good in appearance, and non-destructive testing(NDT) shows the seams are good in quality with no welding defects. Bulge tests show that the maximum pressure of welded EPL is 35 MPa, which can fulfill expansion performance requirements. 相似文献
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Abhay Sharma Ajay Kumar Chaudhary Navneet Arora Bhanu K. Mishra 《The International Journal of Advanced Manufacturing Technology》2009,45(11-12):1096-1103
Heat source models are mathematical expressions that represent the generation term in the fundamental heat transfer equation. Investigators have successfully demonstrated different heat source models for single-wire welding. The present investigation estimates the double ellipsoidal heat source model parameters for twin-wire application. The heat source model parameters have been estimated for varying set of welding conditions. It has been found that the heat source model parameters for twin-wire welding are different from the single-wire welding. Moreover, the heat source model parameters also depend upon process parameters. Effects of welding current, electrode polarity and wire diameter on the size of heat source model have been presented. Flux consumption is also found to play a significant role in deciding the heat source model parameters. 相似文献
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研究一种基于图像质心的焊缝识别新方法.根据焊接熔池视觉图像质心算法及视觉传感器工作原理,推导并建立焊接图像质心与焊接区温度及焊缝中心关系模型.通过焊接温度场的数值化,得到图像质心与焊缝中心关系模型在一定焊接参数条件下的数值解.采用数值仿真分析模型的影响因素,结果表明焊接电流、焊接速度和焊缝宽度对模型曲线影响最为显著.在分析质心与焊缝中心数值解变化趋势的基础上,得到质心偏差与焊缝偏差的经验表达式.在此基础上,对不同焊接参数条件下的模型曲线进行最小二乘拟合,建立质心偏差模型特征参数的样本空间.然后进行多元线性回归分析,确定出经验表达模型的特征参数,从而建立质心偏差关于焊接参数为变量的实用理论模型的函数表达式.焊接工艺试验表明,依据图像质心算法可以较好地识别焊缝中心位置. 相似文献