TA2钛合金开口柱壳外爆碎片分布研究

金属柱壳爆炸膨胀断裂机制及其对碎片分布、特征尺寸的影响是应用物理、力学、兵器工程等领域共同关心的重要课题, 但目前除数值模拟外, 考虑断裂机制的简单二维碎裂模型尚未出现.开展TA2钛合金开口柱壳在不同装药条件下的碎裂实验研究, 通过对软回收碎片的统计及微观分析, 探讨金属柱壳外爆断裂模式及二维碎片分布规律, 结果显示:(1) TA2钛合金柱壳在实验爆压(7 $\sim$ 25 GPa)下宏观断口均为剪切断裂模式, 但机制不同, 在较高爆压下柱壳剪切断裂由多重绝热剪切带破坏控制, 在较低压力下为剪切破坏;(2) 与一维拉伸碎裂相比, 柱壳爆炸碎裂不充分, 碎片质量更符合$\beta=1$ (或更接近1)的指数分布; 爆炸碎裂越充分, 碎片越小并趋于均匀, $\beta$趋于较小的值, 趋向Mott和Linfoot提出的泊松统计分布形式;(3) Rayleigh分布可以较好描述柱壳碎片的宽度分布规律, 不同爆压下柱壳碎片宽度归一化尺寸分布具有相似性, 呈现"量子化"特性, 即存在最小的特征尺寸; (4) TA2柱壳碎片特征尺寸远大于G-K剪切断裂公式预测的尺寸, G-K剪切式描述的是多重绝热剪切带间距.本研究为金属柱壳碎片特征、分布规律及其模型分析提供了重要参考. 

STUDY ON FRAGMENTS DISTRIBUTION OF EXPLOSIVELY DRIVEN CYLINDERS FOR TA2 TITANIUM ALLOY

Understanding the characteristics of fracture mode, fragment distribution and its controlling factor for explosively driven metal cylinders are important topics in applied physics, mechanics, weapon engineering and other fields. However, except for numerical simulation, a simple two-dimensional fragmentation model considering fracture mechanism has not put forward. In this paper, the fragmentation of TA2 titanium cylinders with varying charge were carried out experimentally. Through the analysis of macroscopic fracture and microscopic metallographic for the recovered fragments, the fracture mode and its fragmentation distribution of TA2 metal are discussed. The results show that:(1) The fragmentation of TA2 titanium alloy cylinders is all shear fracture modes under different detonation pressure of 7 $\sim$ 25 GPa, but the mechanism is different, which the fracture controlled by multiple adiabatic shear bands at higher explosion pressure; (2) different from the one-dimensional tensile fragmentation, the fragment mass distribution is modeled as an exponential distribution with $\beta = 1$ due to the insufficient fragmentation of metal cylinders. The $\beta $ can tend to be smaller when the fragmentation of explosively driven cylinders is more sufficient, which would be closer to the Poisson statistical distribution proposed by Mott and Linfoot; (3) The width distribution of cylinder fragments can be well described by the Rayleigh distribution. The normalized width distribution of fragments under different explosion pressures is similar and presents the characteristic of "quantization", which means a minimum characteristic size exists; (4) The characteristic sizes of TA2 shell fragments are much larger than that predicted by the G-K formula, as it is used to describe the distances between multiple adiabatic shear bands. Many factors affect the explosion of cylindrical shell, and the formation of each fragment is random, but the statistical regularity shows that the explosion process and fragment distribution are still predictable overall. The research provides an important reference for fragmentation characteristics, distribution, and model analysis of metal cylinders.