【作者】 郑文健；

【导师】 王浪平；

【作者基本信息】 哈尔滨工业大学 ， 材料工程， 2011， 硕士

【摘要】 高强铝合金薄板焊接结构替代传统的铆接结构能够有效减轻大型客机自重、降低生产成本、增加构件的承载能力。但大型铝合金薄壁件T型结构的双激光束双侧同步焊接(BSLBW)存在的焊接工艺问题、焊接残余应力及变形的控制问题等,使其实际应用受到了一定限制。本文针对某大型客机机身壁板铝合金6156蒙皮与铝合金6056桁条组成的T型接头,进行BSLBW的试验和数值模拟的研究。首先针对T型接头的BSLBW进行不同焊接工艺参数匹配的探索性研究,获得T型接头激光焊较优的工艺参数范围。然后对不同焊接功率和焊接速度条件下的焊缝成形进行了数值模拟和焊接试验,得出焊接功率和焊接速度对焊缝成形的影响规律。最终确定了本文所研究的薄板铝合金T型接头BSLBW的最优工艺。其次计算了单桁条基本件的焊接过程温度场、残余应力和变形,模拟结果与焊后试验测量结果吻合良好。研究结果表明:T型接头角焊缝的纵向残余应力明显高于横向残余应力,纵向压应力分布集中于很小的范围内,且最高应力值达到350MPa;单桁条基本件的焊后变形在一定范围内随焊接线能量的增大而增大。最后针对飞机壁板大型构件的三桁条典型件和七桁条模拟段的焊接温度场、应力场和变形进行了有限元分析,并进行了典型件焊接的试验验证。通过对典型件的三个桁条的焊接顺序优化研究,提出了控制典型件焊后变形方案。在此基础上,针对飞机壁板实际构件模拟段的七个桁条的焊接顺序进行优化研究,按照本文提出的装卡条件采用从两侧向中心逐步对称焊接的顺序,可获得较小的焊接变形。研究成果可用于指导大型客机机身壁板的生产制造过程,可提高生产效率,降低实验成本,从而提高铝合金薄板T型接头BSLBW技术在大型客机制造领域的应用。更多还原

【Abstract】 Thin-walled laser welded aluminum alloy structures can decrease weight, reduce cost and increase the loading capability over conventional riveting. However, laser welding parameters, high residual stresses and distortion have restricted the wide application of aluminum alloy T-joint of BSLBW(bilateral synchronous laser beam welding). Research on experimental and finite element numerical simulation of BSLBW was carried out on T-joint composed of aluminum alloy 6156 plate and 6056 flitch. Numerical simulation was conducted for different laser welding parameters.Experimental and finite element numerical simulation was carried out to obtain the influence of laser power and weld velocity on weld configuration. The most optimized welding parameters of BSLBW are obtained on T-joint of aluminum alloy plate.A sequentially coupled thermal-mechanical analysis on basic specimen of one flitch is undertaken to predict the welding temperature field, residual stress and distortion distribution field. A comparison between the experimental and simulation results shows a good agreement. The result indicated that the temperature grades nearby weld pool were much greater. Longitudinal residual stress of T-joint weld is obviously higher than that of the transverse stress, longitudinal compression stress distribution focused on a very small range, and the peak stress reaches 350MPa. Welding distortion of the basic specimen increases with the welding energy increasing.Three-dimensional finite element model of the typical three flitch specimen has been developed to simulate the temperature field, residual stress distribution and distortion. Experimental testing was carried out to measure the distortions of the typical specimens and verify the FE results. The welding of the typical specimen composed of three flitch and base plate in different welding sequences was simulated to find out welding sequence of the smallest distortion. The distortion controlling measure was proposed. Seven flitch specimens in different welding sequences were calculated to identity the welding sequence of the smallest distortion.Research results can guide manufacturing process of airliner fuselage wall plate to improve production efficiency and reduce testing cost. This research enhances the application of high-strength aluminum alloy BSLBW in the astronautic field更多还原