2024铝合金高温损伤模型的建立及其应用

Establishment and application of high temperature damage model for 2024 aluminum alloy

针对2024铝合金在其高温拉伸过程中颈缩现象显著,实验测得的应力-应变曲线并不能准确反映材料的真实应力应变关系的问题,通过分析高温拉伸曲线中的流变软化现象及微观组织演化规律,认为动态回复和损伤是导致材料软化的主要机制,提出了一种“去耦合”方法求解真实应力-应变曲线。采用由Avrami方程求解所得的动态回复曲线作为高温下“无损伤”2024铝合金的应力应变关系,并引入Johnson-Cook损伤模型描述2024铝合金高温损伤演化过程。利用ABAQUS有限元模拟软件,集成上述应力应变关系和损伤模型,预测了2024铝合金拉伸断裂和方盒件热拉深成形破裂过程。其预测结果和实验基本一致。

Aiming at the problem that the stress-strain curves measured by experiment for 2024 aluminum alloy cannot reflect true stressstrain relationship because of the obvious necking process in high temperature tensile tests,by analyzing the rheological softening phenomenon in high temperature tensile curves and microstructure evolution rule,the dynamic recovery and damage were considered as the main mechanisms leading to material softening,and a“decoupling”method was proposed to obtain the true stress-strain curves.The dynamic recovery curve obtained by the Avrami equation was considered as the stress-strain relationship of“no-damage”2024 aluminum alloy at high temperature,and Johnson-Cook damage model was introduced to describe the damage evolution of 2024 aluminum alloy at high temperature.The stress-strain relationships and the damage models mentioned above were integrated through ABAQUS finite element simulation software,and the processes of tensile fracture of 2024 aluminum alloy and hot deep drawing fracture of square boxes were predicted.The prediction results are basically in good agreement with the experimental results.