钛合金筋板件等温局部加载模具应力分析

Stress analysis of die for Ti-alloy rib-web component isothermal local loading forming

等温局部加载成形技术为航空航天复杂筋板类大型整体构件的成形提供了一种新的途径,但由于构件尺寸大,其成形温度高、时间长、载荷大等工艺特点,对模具提出了更高的要求。文章针对TA15钛合金典型环形高筋薄腹特征结构件等温局部加载成形,分析了等温局部加载模具的结构特点和可能的失效形式,并在此基础上采用DEFORM 3D有限元软件,对成形时模具应力进行了研究,获得了模具载荷和应力分布规律,并进一步分析了模具凹圆角半径和锻件筋条宽度对模具应力的影响。结果表明,等温局部加载成形模具的失效形式,主要为应力集中引起的脆性断裂;加载分区边界附近模具应力较小,离分区边界越远模具应力越大,且应力峰值出现在宽度较小的环形筋型腔凹角处;模具型腔各部分材料填充能力的不一致,是导致模具应力不均匀、局部出现应力集中的主要原因;增大模具凹圆角半径,模具应力降低程度较小,而通过合理的锻件几何尺寸设计,可以改善模具型腔的充填性,能更有效地降低模具应力的不均匀性和应力峰值。文章的研究结果可为等温局部加载成形模具的设计提供参考。

Isothermal local loading forming provides a new approach to form large-scale integral rib-web complex component which are widely used in aerospace industry, while the higher requirement of die strength is needed due to the large dimension of component, high forming temperature, large forming load, and long forming time in the process. Aiming at rib-web annular component of TA15 titanium alloy isothermal local loading process, die structure characteristic and failure mode are analyzed. Die stress was studied by using finite element method based on DEFORM 3D platform. Load and stress distributions of die were obtained. The influences of the die fillet radius and width of rib on die stress were investigated farther. The results show that the failure mode of isothermal local loading die would be brittle fracture caused by stress concentration; in the zone near the border of die partition the stress is smaller, and the peak stress appears near the concave corner of rib cavity with smaller width in bottom die. The nonunifortuity in filling ability of the material to different parts of die cavity leads to the unequal distribution of die stress and local stress concentration. Proper design of component geometry is a more effective way of reduce unequal die stress and peak value rather than increasing corner radius. The results obtained could be as guide to the design of isothermal local loading forming die.