粘塑性损伤模型模拟准超塑性单轴拉伸行为

发展了Chaboche粘塑性本构模型的大变形隐式算法，用损伤(DM)和无损伤(NDM)模型模拟准超塑性单轴拉伸。发现变形过程可分为三个阶段：均匀变形、颈缩发展、断裂破坏阶段。DM可准确模拟前两个阶段变形，NDM只能较好地模拟均匀变形阶段，表明DM可以较精确地描述稳定发展的动态过程。由于有限元方法只能描述连续介质，因此对于断裂破坏阶段，NDM模拟载荷大于试验结果，DM的载荷小于试验结果，这是由高应变速率敏感性造成。DM能够描述试验中出现地多处颈缩现象，局部应变速率分布随时间演化反映了颈缩发展程度。严重颈缩部位的距离代表着超塑性变形能力，距离越大，抗颈缩能力越好。

Quasi-Superplastic Uniaxial Tension Simulation Using Viscoplastic Damage Model

The large deformation implicit algorithm on Chaboche viscoplastic constitutive equations is developed. Simulations of quasi-superplastic uniaxial tensile are implemented using damage model and non-damage model. From analysis of force/displacement curves, the process of quasi-superplastic deformation is divided into three stages: uniform deformation, necking development and rupturing. DM results show good agreements with experimental results for the two former stage, while NDM could only describe the first stage well. During rupturing process, force results calculated by DM are higher and lower by NDM than experimental ones due to higher strain rate sensitivity. DM can describe the phenomenon of multi-neckings, which is in good agreements with experimental results. Evolution of local strain rate distributions is indicative of necking extent. The longer distance between two serious neckings shows good ability to resist necking formation.