In this study, smooth walled tubular specimens (L, Do, t: 10 0 × 34 × 3 mm) of 18Cr-8Ni stainless steel were vertically set on a steel support plate and impacted at the top side vertically or axially by circular flyer plates (D, h: 80 × 20 mm) of the same material. The direct explosive driver was a slab-like installed powder PETN (charged density: 0.90-0.95 ×103 kg·m-3, height variations: 10, 15 and 20 mm) initiated by simultaneous explosion of paralleled fine copper wire rows placed over the entire outer surface using a discharge current from a high-voltage capacitor bank. All the tested cylinders impacted at the estimated velocities of around 80, 92 and 120 m·s-1 were locally buckled and plastically deformed mainly near the bottom part showing the almost symmetrical patters of flattened waves with the number of 1.5, 2.0 and 3.0 respectively. A hydro code Autodyn 2D was adopted to simulate the experimental phenomena generated in this explosive driven impact test system for cylinders. The numerical results reproduced experimental final lengths and deformation patterns of impacted cylinders successfully for three cases. The numerical time-histories of momentum for the flyer plates and axial stresses at the sectional surface in the bottom support plate indicated the momentum absorption ratios of 22 – 31 %.
本研究では，鋼鉄板上に垂直に設置した18Cr-8Niステンレス鋼製円筒（軸長100 mm，外形34 mm，肉厚3 mm） に，上方から同材の飛翔円板（直径80 mm，厚さ20 mm）を軸方向に高速衝突させた。衝突円板は，上面に設置した粉末状PETN爆薬（密度0.90−0.95×103 kg･m-3，薬厚10，15，20 mm)の自由表面に平行銅細線を配し衝撃大電流で一斉爆発させて生成させた平面爆轟ガスによって飛翔させた。 供試円筒には，薬厚量に応じて約80，92，120 m･s-1の推定速度で円板が衝突し，いずれも円筒の支持端側で軸対象波型の塑性座屈変形が生じており，その折畳み波数は各々1.5，2.0，3.0であった。また衝撃解析コードAutodyn 2Dを用いて本研究の爆薬駆動円筒衝撃試験システムでの実験現象について数値シミュレーションを行った。その数値解析結果は，円板衝突実験による円筒の全体収縮変形量や折畳パターンを良好に再現していた。そして飛翔板の運動量と円筒支持板内の断面を通過する軸方向応力の時間履歴解析から本研究における円筒の運動量吸収率が22−31 %であることが分かった。
Dynamic axial buckling, Stainless steel cylinder, Explosive driven flyer, Symmetrically deformed fold,Momentum absorption ratio.