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arXiv 2103.03128astro-ph.EP
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弹坑形状作为金属物体撞击环境的可能记录:温度、撞击速度和撞击物密度的影响

Crater shape as a possible record of the impact environment of metallic bodies: Effects of temperature, impact velocity and impactor density

Ryo Ogawa, Akiko M. Nakamura, Ayako I. Suzuki, Sunao Hasegawa

摘要:

金属天体是分化天体的核心,是铁陨石的来源,被认为是在迁移到主小行星带之前在类地行星区域早期形成的。类地行星区域和主小行星带之间的地面温度和相互碰撞速度不同。为了研究弹坑形状对温度、速度和撞击物密度的依赖性,我们对室温和低温铁陨石和铁合金目标(碳钢SS 400和铁镍合金)进行了撞击实验,速度为0.8-7公里/秒。射弹是岩石圆柱体和金属球体和圆柱体。斜冲击实验也进行了使用不锈钢弹丸和SS 400钢目标,产生更突出的径向图案在室温下比在低温下的downrange。根据$π$组陨石坑比例关系,使用无量纲参数集测量和编制陨石坑直径和深度。使用iSALE-2D代码和Johnson-Cook强度模型进行二维数值模拟。实验和数值计算结果表明,弹坑的深度和直径随着温度的降低而减小,这增强了靶的强度,并且随着撞击速度的降低而减小。深度的下降趋势比直径的下降趋势更显著,即,对于低温和低速条件,深度/直径比较小。岩石抛射体形成的弹坑的深径比小于金属抛射体形成的弹坑的深径比。我们的研究结果表明,金属表面撞击坑深径比的频率分布可以作为金属撞击环境的一个探针。

英文摘要:

Metallic bodies that were the cores of differentiated bodies are sources of iron meteorites and are considered to have formed early in the terrestrial planet region before migrating to the main asteroid belt. Surface temperatures and mutual collision velocities differ between the terrestrial planet region and the main asteroid belt. To investigate the dependence of crater shape on temperature, velocity and impactor density, we conducted impact experiments on room- and low-temperature iron meteorite and iron alloy targets (carbon steel SS400 and iron-nickel alloy) with velocities of 0.8-7 km/s. The projectiles were rock cylinders and metal spheres and cylinders. Oblique impact experiments were also conducted using stainless steel projectiles and SS400 steel targets which produced more prominent radial patterns downrange at room temperature than at low temperature. Crater diameters and depths were measured and compiled using non-dimensional parameter sets based on the $π$-group crater scaling relations. Two-dimensional numerical simulations were conducted using iSALE-2D code with the Johnson-Cook strength model. Both experimental and numerical results showed that the crater depth and diameter decreased with decreasing temperature, which strengthened the target, and with decreasing impact velocity. The decreasing tendency was more prominent for depth than for diameter, i.e., the depth/diameter ratio was smaller for the low temperature and low velocity conditions. The depth/diameter ratios of craters formed by rock projectiles were shallower than those of craters formed by metallic projectiles. Our results imply that the frequency distribution of the depth/diameter ratio for craters on the surface of metallic bodies may be used as a probe of the past impact environment of metallic bodies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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