Impact fragmentation experiments of basalts and pyrophyllites
Impact fragmentation experiments of basalts and pyrophyllites
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玄武岩和叶腊石的冲击破碎实验
DOI：
10.1016/0019-1035(84)90114-3
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发表时间：
1984
期刊：
影响因子：
3.2
通讯作者：
S. Kawakami
中科院分区：
文献类型：
--
作者：
Y. Takagi;H. Mizutani;S. Kawakami
报道了玄武岩和叶蜡石的冲击破碎实验结果。铝柱形弹以70~990m/s的速度撞击立方玄武岩和叶蜡石靶板。靶和射弹的重量分别为20g~3.3 kg和2~20g。测量了撞击产生的碎片的重量，并检查了碎片的尺寸分布。与以前研究中使用的传统弹丸单位目标质量动能E/mt相比，归一化为原始目标质量(Mt)的最大破片质量(ML)数据与无因次撞击应力pI的相关性更好，pI是由H.Mizutani，Y.Takagi和S.Kawakami(1984，在准备阶段)引入的一个新的标度参数。本文所获得的玄武岩的所有数据可概括为：mL/mt=2.95×10−2pi−1式中，PI=P0L3/YR3，P0=峰值冲击压力，L=弹丸尺寸，R=靶材尺寸，Y=靶材强度。然而，对于铝靶，在相同PI的撞击下，其ML/MTI比脆性靶大2.5个数量级。用log N-log(m/mt)图表示的碎片的尺寸分布被分成由两个拐点包围的三个区域。在每个区域中，曲线用N(>；mmt)=A(M Mt)−a表示。在大尺寸和中等尺寸区域，logN-log(M Mt)曲线的斜率a与无量纲冲击应力PI正相关，表示为a=C3+a3logPI。另一方面，最小尺寸范围内的坡度a几乎是恒定的，其值在0.5%到0.7%之间(1 2−2 3)。结果表明，水谷、高木和川上的新标度参数pI很好地刻画了碰撞碎裂的尺度，实验数据可能为行星碰撞过程提供新的线索。
Results of impact fragmentation experiments for basalts and pyrophyllites are reported. Aluminum cylindrical projectiles were impacted on cubic basalt and pyrophyllite targets at velocities of 70 to 990 m/sec. The targets and projectiles were 20 g to 3.3 kg and 2 to 20 g in weight respectively. Weights of the fragments produced by impacts were measured and the size distributions of fragments were examined. Data of the largest fragment mass (mL) normalized to the original target mass (Mt), mL/Mt, correlate better with the nondimensional impact stress, PI, a new scaling parameter introduced by H. Mizutani, Y. Takagi, and S. Kawakami (1984, in preparation) than the conventional projectile's kinetic energy per unit target mass, E/Mt, used in the previous studies. All the mL/Mtdata for basalts obtained in the present study are summarized by mL/Mt= 2.95 × 10−2PI−1where PI= P0L3/YR3, P0= peak shock pressure, L = projectile size, R = target size and Y = material strength of target. For aluminum targets, however, the mL/Mtis 2.5 orders of magnitude larger than that for brittle targets at impacts with the same PI. Size distributions of fragments expressed in a log N - log (m/Mt) diagram divided into three regimes bounded by two inflection points. In each regime the curve is expressed by N (> m Mt) = A ( m Mt)−a. The slopes, a, of the log N - log ( m Mt) curves in the regimes of a large and a medium size range are positively correlated with the nondimensional impact stress, PI, and expressed as a = C3+ a3log PI. The slopes, a, in the smallest size range are, on the other hand, nearly constant and have values of 0.5 to 0.7 ( 1 2 − 2 3 ) . Present results indicate that the impact fragmentation is scaled well by the new scaling parameter, PI, of Mizutani, Takagi, and Kawakami and that the present experimental data may shed new light on planetary impact processes.