In this work, we perform a comprehensive study of the dynamic deformation and fracture of brass, including Taylor tests with classical and profiled cylinders and ball throwing experiments reaching the strain rates of about (0.1−1)/μs, as well as atomistic and continuum-level numerical modeling. Molecular dynamics (MD) simulations are used to construct the equation of state (EOS) of brass and to study its fracture characteristics at shear deformation under negative pressure. An original model of fracture under combined tensile-shear loading is formulated, which takes into account both the accumulation of empty volume in the process of lattice loosening due to the lattice defect production in the course of plastic deformation and further mechanical growth of voids controlled by the dislocation plasticity. This atomic-scale model is transmitted to the macroscopic experiment-scale level and embedded into 3D dislocation plasticity model to describe the dynamic deformation and fracture of brass using the numerical scheme of smoothed particle hydrodynamics (SPH). A part of experimental data is used to find the optimal parameters of the dislocation plasticity model by means of the Bayesian global optimization method accelerated with the help of artificial-neural-network (ANN)-based emulator of the 3D model. Another part of experimental data is used to fit the fracture model parameter. The remaining experimental data, which are not used in the parameterization, are applied to verify the parameterized model. The developed physical-based model provides correct and meaningful description of the dynamic deformation and fracture of brass, while the developed formalized approach to its parameterization opens a way to wider use of this type of models in the engineering applications, including studies on dynamic performance and high-speed processing technologies.

中文翻译：

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黄铜的动态变形和断裂：实验和基于位错的模型


在这项工作中，我们对黄铜的动态变形和断裂进行了全面研究，包括使用经典和异形圆柱体的泰勒试验和应变率约为 （0.1−1）/μs 的抛球实验，以及原子和连续体级数值建模。分子动力学 （MD） 模拟用于构建黄铜的状态方程 （EOS），并研究其在负压下剪切变形时的断裂特性。建立了一个原始的拉伸-剪切联合载荷下的断裂模型，该模型既考虑了塑性变形过程中晶格缺陷产生导致晶格松动过程中空体积的积累，也考虑了位错塑性控制的空隙的进一步机械增长。该原子尺度模型被传输到宏观实验尺度水平，并嵌入到 3D 位错塑性模型中，以使用平滑粒子流体动力学 （SPH） 的数值方案描述黄铜的动态变形和断裂。在基于人工神经网络 （ANN） 的 3D 模型仿真器的帮助下，通过贝叶斯全局优化方法加速，使用部分实验数据来寻找位错塑性模型的最佳参数。另一部分实验数据用于拟合裂隙模型参数。其余的实验数据（未用于参数化）用于验证参数化模型。 开发的基于物理的模型为黄铜的动态变形和断裂提供了正确和有意义的描述，而开发的参数化形式化方法为在工程应用中更广泛地使用此类模型开辟了道路，包括动态性能和高速加工技术的研究。