Dimensionality scaled penetration experiments: Aluminum targets and glass projectiles 50 μm to 3.2 MM in diameter

Summary Spherical soda-lime glass projectiles 50, 150, 1000 and 3175 μm in diameter (Dp) in aluminum targets (series 1100; “annealed”) of variable thickness T, were used to determine how the penetration-hole diameter (Dh) varied as a function of Dp/T at a constant impact velocity of 6 km/s. The target thickness ranged from infinite half-space geometries to 0.8 μm thick foils. Virtually identical morphologies characterize the penetration holes, no matter what projectile size, at equivalent Dp/T conditions. The relative hole diameter (Dh/Dp) decreases systematically with increasing Dp/T from Dh ≅ 4Dp for massive targets, to Dh = Dp for very thin foils. A modest dependence on the absolute projectile size is observed; comparatively small cracters, yet relatively large penetration holes are produced by the smallest (50 μm) impactors. Nevertheless, linear dimensional scaling seems suitable for first-order estimates of Dp from the measurement of Dh and T on space-exposed surfaces. The projectile fragments and the debris dislodged from the target were intercepted by witness plates that were located behind the target. The dispersion angle of this debris cloud depends on the thickness of the target. In addition, millimeter-sized impactors are collisionally fragmented with greater ease than small impactors. Furthermore, we observe that systematic changes in the specific energy of dislodged projectile and target material occur as a function of Dp/T. While linear scaling of target and projectile dimensions is a useful framework to explain many observations and associated shock processes, we suggest that consideration of the absolute and relative shock-pulse duration in the projectile (tp) and target (tt) may ultimately be the more useful approach. It implicitly accounts for all dimensions and, additionally, for specific impact velocities and pertinent material properties, via equations-of-state, for the impacting pair.

[1]  Andrew J. Piekutowski,et al.  A simple dynamic model for the formation of debris clouds , 1990 .

[2]  Eberhard Grün,et al.  The penetration limit of thin films , 1980 .

[3]  B. P. Denardo,et al.  Experimental investigation of the momentum transfer associated with impact into thin aluminum targets , 1969 .

[4]  J. M. McGlaun,et al.  CTH: A three-dimensional shock wave physics code , 1990 .

[5]  J. A. M. McDonnell,et al.  An Empirical Penetration Equation for Thin Metallic Films Used in Capture Cell Techniques , 1985 .

[6]  D. Sawle.  Hypervelocity impact in thin sheets and semi- infinite targets at 15km/sec , 1970 .

[7]  D. Brownlee,et al.  The flux of meteoroids and orbital space debris striking satellites in low Earth orbit , 1986, Nature.

[8]  William P. Schonberg,et al.  Penetration and ricochet phenomena in oblique hypervelocity impact , 1988 .

[9]  A. J. Stilp,et al.  Debris cloud expansion studies , 1990 .

[10]  A. Gurson.  The effect of geometric scale on impact induced fragmentation, and its application to the design of dual plate armor , 1990 .

[11]  K. A. Holsapple,et al.  On the Scaling of Crater Dimensions 2. Impact Processes , 1982 .

[12]  P. Anz-meador,et al.  Orbital Debris Environment for Spacecraft Designed to Operate in Low Earth Orbit , 1989 .

[13]  Eric L. Christiansen,et al.  Performance equations for advanced orbital debris shields , 1992 .

[14]  James S. Wilbeck,et al.  Review of hypervelocity penetration theories , 1987 .

[15]  Burton G. Cour-Palais,et al.  Hypervelocity impact in metals, glass and composites , 1987 .

[16]  S. L. Passman,et al.  Stability and fragmentation of ejecta in hypervelocity impact , 1990 .

[17]  C. Simon.  Hypervelocity impact testing of micrometeorite capture cells in conjunction with a PVDF thin-film velocity/trajectory sensor and a simple plasma velocity detector , 1993 .

[18]  M. Zolensky,et al.  Meteoroid and Debris Impact Features Documented on the Long Duration Exposure Facility: A Preliminary Report , 1990 .

[19]  Mark J. Cintala,et al.  Impact‐induced thermal effects in the lunar and Mercurian regoliths , 1992 .

[20]  J. W. Gehring,et al.  CHAPTER IV – THEORY OF IMPACT ON THIN TARGETS AND SHIELDS AND CORRELATION WITH EXPERIMENT , 1970 .

[21]  F. Stadermann,et al.  SIMS chemical analysis of extended impact features from the trailing edge portion of experiment AO187-2 , 1992 .

[22]  A. B. Wenzel,et al.  A review of explosive accelerators for hypervelocity impact , 1987 .

[23]  Hugo Fechtig,et al.  Collisional balance of the meteoritic complex , 1985 .

[24]  C. Yew,et al.  Hypervelocity impact of two spheres , 1989 .