【作者】 王倩；

【导师】 童国权；

【作者基本信息】 南京航空航天大学 ， 航空宇航制造工程， 2010， 硕士

【摘要】 超塑胀形作为超塑成形的重要应用,已经广泛应用于航空、航天、船舶、汽车、电子通信等行业,但在超塑性机理、力学特性以及应用技术等方面都有待于进一步深入研究。而超塑胀形试验目前被认为是研究板材超塑成形性能的重要手段。本文主要研究工作包括两个方面:第一,针对AA5083铝合金圆锥件,利用有限元仿真软件获得不同加载方式下的压力-时间曲线进行胀形试验,比较不同背压情况下材料的组织孔洞缺陷以及成形极限,研究背压对于AA5083铝合金的超塑胀形性能的影响。第二,针对TC4钛合金圆筒件,利用有限元仿真软件获得压力-时间曲线进行胀形试验,而后在筒底部切割试样,研究了超塑变形量对材料疲劳强度、静力强度、塑性以及晶粒尺寸的影响。试验结果表明:对于AA5083铝合金圆锥件,背压有效抑制了孔洞的萌生和长大,提高了材料的成形极限和胀形延伸率,在不加背压情况下,圆锥件顶点处胀形延伸率为266%,在加1.5MPa和3MPa背压时,胀形延伸率分别增长至324%和567%。对于TC4钛合金圆筒件,当胀形延伸率小于100%时,TC4的静力强度有明显的下降,当胀形延伸率e增加至230%时,强度极限和屈服强度基本保持不变;此外,随着超塑胀形延伸率e增加,TC4钛合金的条件疲劳强度降低。更多还原

【Abstract】 Superplastic pneumatic bulge forming is an important application of superplastic forming, which has been widely appied in the aeronautics, astronautics, shipping, automibiles, electronic communications and etc. However, it is still needed of futher research on the mechanisms, and application technologies of superplastic pneumatic bulge forming. Superplastic bulge experiment is considered to be the best way to investigate the superplastic forming performance of sheets.It is mainly researched on two sides in this paper:Firstly, finite element simulation is utilized to get the p-t curve for different forming ways, and then caviation and forming limits of the sheets which formed in different conditions are compared to investigate the effect of back pressure on the superplastic forming performance.Secondly, finite element simulation is utilized to get the p-t curve and then the superplastic bulge test is conducted. After that, the effects of deformation on condition fatigue strength, static strength, plasticity and the grain size of TC4 are evaluated.It is shown by the experiment that back pressure can effectively restrain the generating and growing of the caviation and then the forming limit of AA5083 aluminium alloy cone workpiece is improved. The bulging elongation of the vertex of the cone workpiece is 266% without back pressure while they increase to 324% under the condition of 1.5MPa back pressure and 567% under the condition of 3MPa back pressure. And that for the TC4 titanium cylinder parts, static strength declines when bulge elongation is less than 100% while strength limit and yield strength are keep constant proximately. Besides this, condition fatigue strength declines as the elongation increases.更多还原