有限应变范围内循环蠕变的嵌套乘法分裂模型
Modeling of cyclic creep in the finite strain range using a nested multiplicative split
摘要：
提出了一种新的循环蠕变唯象模型，该模型适用于材料的有限蠕变变形。该模型考虑了蠕变应变速率的瞬时增加对载荷反转的影响。为了扩大模型的适用范围，蠕变过程完全耦合到经典的Kachanov-Rabonov损伤演化。因此，所提出的模型描述了蠕变的所有三个阶段。大应变运动学描述的几何精确的方式使用嵌套乘法分裂的假设，最初提出的狮子有限应变塑性。该模型是可容许的，客观的，和w-不变的。讨论了所提出的演化方程的隐式时间积分。相应的数值算法已在商用有限元程序MSC. MARC中实现。使用该代码，该模型进行了验证，使用真实的实验数据的循环扭转厚壁管试样的D16 T铝合金。数值计算的应力分布表现出“骨架点”内的标本。
英文摘要：
A new phenomenological model of cyclic creep is proposed which is suitable for applications involving finite creep deformations of the material. The model accounts for the the effect of the transient increase of the creep strain rate upon the load reversal. In order to extend the applicability range of the model, the creep process is fully coupled to the classical Kachanov-Rabonov damage evolution. As a result, the proposed model describes all the three stages of creep. Large strain kinematics is described in a geometrically exact manner using the assumption of a nested multiplicative split, originally proposed by Lion for finite strain plasticity. The model is thermodynamically admissible, objective, and w-invariant. Implicit time integration of the proposed evolution equations is discussed. The corresponding numerical algorithm is implemented into the commercial FEM code MSC.MARC. Using this code, the model is validated using real experimental data on cyclic torsion of a thick-walled tubular specimen made of the D16T aluminium alloy. The numerically computed stress distribution exhibits a "skeletal point" within the specimen.
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