Johnson-Cook parameter evaluation from ballistic impact data via iterative FEM modelling
Johnson-Cook parameter evaluation from ballistic impact data via iterative FEM modelling
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DOI：
10.1016/j.ijimpeng.2017.10.012
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发表时间：
2018-02-01
影响因子：
5.1
通讯作者：
Clyne, T. W.
中科院分区：
文献类型：
--
作者：
Burley, M.;Campbell, J. E.;Clyne, T. W.
提出了一种估算大块金属材料塑性变形应变速率敏感性参数的方法。它涉及到一个硬球形弹丸的弹道影响，然后重复有限元建模，预测的结果（位移-时间图和/或残留的波形）与实验进行了系统的比较。通过寻求最大化表征实验结果与预测结果之间的一致性的“拟合优度”参数（g）的值来找到“正确”参数值。FEM模型的输入包括表征（温度相关的）准静态塑性的数据。由于应变速率敏感性的特点是由一个单一的参数值（C在约翰逊库克制定），其最佳值的收敛是直接的，虽然参数表征界面摩擦也是必需的。使用实验数据（加工硬化和退火）的铜样品，这一过程已经进行，并已获得C的最佳拟合值（类似于0.016和类似于0.030）。在这些实验中的应变率操作类似于10（4）-10（6）s（-1）。目前正在开发能够从实验数据中自动提取这些数值的软件包。
A methodology is presented for evaluating a strain rate sensitivity parameter for plastic deformation of bulk metallic materials. It involves ballistic impact with a hard spherical projectile, followed by repeated FEM modelling, with predicted outcomes (displacement-time plots and/or residual indent shapes) being systematically compared with experiment. The "correct" parameter value is found by seeking to maximise the value of a "goodness of fit" parameter (g) characterizing the agreement between experimental and predicted outcomes. Input for the FEM model includes data characterizing the (temperature-dependent) quasi-static plasticity. Since the strain rate sensitivity is characterised by a single parameter value (C in the Johnson Cook formulation), convergence on its optimum value is straightforward, although a parameter characterizing interfacial friction is also required. Using experimental data from (both work-hardened and annealed) copper samples, this procedure has been carried out and best-fit values of C (similar to 0.016 and similar to 0.030) have been obtained. The strain rates operative during these experiments were similar to 10(4)-10(6) s(-1). Software packages allowing automated extraction of such values from sets of experimental data are currently under development.