Effect of pre-strain on springback behavior after bending in AA 6016-T4: Experiments and crystal plasticity modeling
Effect of pre-strain on springback behavior after bending in AA 6016-T4: Experiments and crystal plasticity modeling
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DOI：
10.1016/j.ijsolstr.2023.112485
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发表时间：
2023-11
影响因子：
3.6
通讯作者：
Dane Sargeant;Zahidul Sarkar;Rishabh Sharma;Marko Knezevic;D. Fullwood;Michael P. Miles
中科院分区：
文献类型：
--
作者：
Dane Sargeant;Zahidul Sarkar;Rishabh Sharma;Marko Knezevic;D. Fullwood;Michael P. Miles
在铝合金板材中建立回弹模型是一个挑战，特别是当应用复杂的应变路径时。本文介绍了AA 6016-T4板材的纯弯曲实验结果，其中各种塑性预应变首先施加在弯曲之前。基于晶体塑性的弹塑性自洽（EPSC）模型，包括背应力的硬化规律的影响，用于预测卸载后的最终零件形状。在模型中的背应力项进行校准，使用几何必要的位错（GND）的内容，实验测量的高分辨率电子背散射衍射（HREBSD）。EPSC模型预测了无应变1 mm AA 6016-T4板材的前冲角，在最差情况下误差为0.4%（0.3°），而J2塑性各向同性模型预测的前冲角高出2.4%（2°）。对于单轴，平面应变，和双轴预应变的情况下，首先赋予弯曲前的片材，EPSC模型与背应力准确地预测从回弹到回弹的过渡，而没有背应力的EPSC模型没有。背应力对模型精度的影响，增加了更大的预应变水平，似乎是相关的统计存储的位错（SSD）密度计算的模型在每个预应变步骤结束时。
Modeling springback in sheet materials is challenging in aluminum alloys, especially when a complex strain path is applied. This paper presents results from pure bending experiments on AA 6016-T4 sheet material, where various plastic pre-strains were first applied prior to bending. A crystal plasticity based elasto-plastic self-consistent (EPSC) model that includes the effect of backstress in the hardening law was used to predict final part shape after unloading. The backstress term in the model was calibrated using geometrically necessary dislocation (GND) content, measured experimentally by high resolution electron backscattered diffraction (HREBSD). The EPSC model predicted springforward angles for unstrained 1 mm AA 6016-T4 sheet with an error of 0.4% (0.3°) in the worst case, while the J2 plasticity isotropic model overpredicted springforward angles by as much as 2.4% (2°). For cases where uniaxial, plane-strain, and biaxial pre-strains were first imparted to the sheets before bending, the EPSC model with backstress accurately predicted the transition from springforward to springback, while the EPSC model without backstress did not. Backstress influence on model accuracy, which increased with greater pre-strain levels, appears to be correlated to the statistically stored dislocation (SSD) density computed by the model at the end of each pre-strain step.