(北京航空航天大学 机械工程及自动化学院，北京 100083)
摘 要: 基于板材的基础性能参数，以M-K理论为基础，在不同温度下对5A90铝锂合金的成形极限图进行理论计算。确定了理论预测成形极限图时所需的初始厚度不均度(f)在不同温度下的值，其值在室温下为0.95，在较高温度下为0.995。预测了材料参数应变强化指数(n)、应变速率敏感性指数(m)对5A90铝锂合金的成形极限曲线的影响规律。结果表明，成形极限曲线随m值和n值的增大而上升。同时，对7种变形温度下铝锂合金的成形极限图进行了预测，并在25~300 ℃温度范围内对其进行成形极限实验，通过对实验曲线与理论预测曲线的对比分析，验证了理论预测的可行性和准确性。
关键字: 铝锂合金；成形极限图；理论预测；M-K模型
（School of Mechanical Engineering and Automation, Beihang University, Beijing 100083, China）
Abstract:The forming limit diagrams (FLDs) of 5A90 Al-Li alloy were determined analytically based on the Marciniak-Kuczynski concept of localized necking using the constitutive equation. The initial thickness imperfection parameter, f, at various temperatures was determined, which is an important parameter in predicting FLDs. The f-values are 0.95 at room temperature and 0.995 at elevated temperatures. The effects of the strain-hardening exponent (n-value), and strain-rate exponent (m-value) on the FLDs were predicted, and it is shown that the forming limit strain increases with increasing n-value and m-value. Furthermore, the FLDs of Al-Li alloy were predicted at seven temperatures, and the FLDs tests of 5A90 Al-Li alloy in the forming temperature range of 25−300 ℃ were carried out. The predicted results of the FLDs are in qualitative agreement with the experimental observations.
Key words: aluminum-lithium alloy; forming limit diagram; theoretical prediction; M-K model
