A new interpretation of the mechanical properties of the Gibeon meteorite.
A new interpretation of the mechanical properties of the Gibeon meteorite.
复制标题
对吉遍陨石机械特性的新解释。
DOI：
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发表时间：
1974
期刊：
影响因子：
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通讯作者：
J. Remo
中科院分区：
文献类型：
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作者：
Alan A. Johnson;J. Remo
重新解释了Gordon在1970年报道的一组关于吉宾陨石拉伸性质的温度和应变率依赖关系的结果。这些结果表明，陨石材料在50°K左右的低应变率拉伸试验中经历了韧脆转变，估计在小行星撞击条件下的转变温度约为200°K。因此，如果内部静水压力不显著降低转变温度，材料将以脆性的方式破碎，产生没有塑性变形的陨石碎片。对压力对转变温度影响的近似计算表明，半径大于约140公里的小行星不会发生脆性行为。因此，由于陨石碎片很少显示出严重塑性变形的迹象，因此得出的结论是，这是母行星大小的近似上限。J·A·伍德(1964)对八面体中镍组分剖面的研究导致了对母小行星半径的估计，这些小行星的星等大致相同。我们140公里的值可能在两个方向上都有大约50%的误差。太阳系中现在存在的较大的小行星大约有这个大小。
A set of results on the temperature and strain rate dependence of the tensile properties of the Gibeon meteorite reported by Gordon in 1970 is reinterpreted. It is shown that these results indicate that the meteorite material undergoes a ductile-brittle transition in low strain rate tensile tests at about 50°K. It is estimated that under asteroidal impact conditions the transition temperature would be about 200°K. Thus provided that the internal hydrostatic pressure did not depress the transition temperature significantly, the material would fragment in a brittle manner yielding meteoritic fragments free of plastic deformation. An approximate calculation of the effect of pressure on the transition temperature shows that brittle behavior would not occur in asteroids having radii greater than about 140 km. Thus since meteoritic fragments rarely show signs of gross plastic deformation, it is concluded that this is an approximate upper limit to the size of the parent asteroids. Work on the nickel composition profile in octahedrites by J. A. Wood (1964) led to an estimate of the radii of the parent asteroids of about the same magnitude. Our value of 140 km is probably subject to an error of about 50% in either direction. The larger asteriods now present in the solar system are of about this size.