Abstract Expansion and fragmentation of metallic cylinders is an important area of study both for designing munitions and mitigation techniques against fragments as well as in the failure of pressurised pipes in industry. Most of the reported studies on fragmentation have been carried out by detonating explosively filled metallic cylinders. However, this approach has inherent limitations in terms of both safety and repeatability – not least due to packing issues with explosive fills. Fragmentation studies on hollow metallic cylinders of both mild and stainless steel of various thicknesses (2–4 mm) were carried out by firing a polycarbonate projectile from a single-stage light gas gun. Strain rates of the order of 2 × 104 s−1 were observed at cylinder expansion velocities of 400–450 m s−1, calculated from flash X-ray radiographs. The differences in fragmentation behaviour of both materials was observed, attributed to their different response to high strain-rate loadings. Microscopic analysis of mild steel fragments showed interesting alignment of ferrite and pearlite grains, similar to reported effects of explosive loading. This suggests the potential to employ this technique to simulate explosive cylinder expansion in a non-explosive laboratory environment enabling a convenient recovery of fragments. Numerical modelling with using ANSYS AUTODYN® allowed for a better understanding of the various parameters controlling expansion and fragmentation. Analysis of recovered fragments by a Fragment Weight Distribution Map (FWDM), a method generally used for characterising pipe bombs, could clearly demonstrate the effect of casing material and thickness.

中文翻译：

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非爆炸汽缸膨胀技术的碎片研究

摘要 金属圆柱体的膨胀和破片是设计弹药和防止破片的缓解技术以及工业中加压管道故障的重要研究领域。大多数报道的关于破碎的研究都是通过引爆装满炸药的金属圆柱体来进行的。然而，这种方法在安全性和可重复性方面存在固有的局限性——尤其是由于爆炸性填充物的包装问题。通过从单级轻气枪发射聚碳酸酯射弹，对不同厚度（2-4 毫米）的低碳钢和不锈钢中空金属圆柱体进行了碎裂研究。在 400–450 m s-1 的气缸膨胀速度下观察到 2 × 104 s-1 数量级的应变率，根据闪光 X 射线照片计算。观察到两种材料的碎裂行为差异，归因于它们对高应变率载荷的不同响应。低碳钢碎片的显微分析显示出有趣的铁素体和珠光体晶粒排列，类似于报道的爆炸载荷效应。这表明采用这种技术在非爆炸性实验室环境中模拟爆炸性圆柱体膨胀的潜力，从而能够方便地回收碎片。使用 ANSYS AUTODYN® 进行数值建模可以更好地了解控制膨胀和破碎的各种参数。通过碎片重量分布图 (FWDM) 分析回收的碎片，这是一种通常用于表征管炸弹的方法，可以清楚地证明外壳材料和厚度的影响。