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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.
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Discussion includes recent enhancements to the BUMPER-II program and input files in support of Shuttle Return to Flight. Improvements to the mesh definitions of the finite element input model will be presented. A BUMPER-II analysis process that was used to estimate statistical uncertainty is introduced.
Mathematical model for determining ballistic limit of double-walled meteoroid bumper systems
Design of super critical pressure cryogenic storage and supply equipment with radial bumper shield
One dimensional analysis of hypervelocity impact of pellet onto thin bumper using finite difference techniques
Fracture of bumper protected fuel tanks subjected to hypervelocity meteoroid impact, applying method of characteristics to stress wave propagation in tank walls
Experimental investigation of meteoroid-bumper impact, debris cloud expansion, and second surface pressure loading
Failure modes of bumper hull structures applied to meteoroid hazards
Fracture of bumper protected fuel tanks subjected to hypervelocity meteoroid impact, applying method of characteristics to stress wave propagation in tank walls
A study was made of the meteoroid impact resistance of bumper-protected mainwalls of both solid aluminum and polycarbonate-aluminum laminates. Semi-empirical models of the debris cloud and stress waves were formulated. Results indicated that a laminated mainwall affords greater impact resistance than a solid aluminum mainwall of the same weight.
Four of the eight available double layer microparticle capture cells, flown as the experiment A0023 on the trailing (West) face of LDEF, have been extensively studied. An investigation of the chemistry of impactors has been made using SEM/EDX techniques and the effectiveness of the capture cells as bumper shields has also been examined. Studies of these capture cells gave positive EDX results, with 53 percent of impact sites indicating the presence of some chemical residues, the predominant residue identified as being silicon in varying quantities.
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Single aluminum meteoroid shields for space vehicles
An investigation has been made of the interaction of meteoroids with shielded structures. The interaction has been simulated by the impact of Lexan cylinders onto lead shields in order to provide the vaporous debris believed to be created by meteoroid impact on a space vehicle. Shock compression data for Lexan was determined. This, in combination with the known shock compression data for the lead shield, has permitted the definition of the initial high pressure states in the impacted projectile and shield. The debris from such impact events has been permitted to interact with aluminum main walls. The walls were chosen to be sufficiently large to be effectively infinite in diameter compared to the loaded area. The thickness of the wall and the spacing from the shield were varied to determine the effect of these parameters. In addition, the effect of having a body of water behind the wall has been assessed. Measurements of the stagnation pressure in the debris cloud have been made and correlated with the response of the main wall.
The analysis of hypervelocity impact of particles on a detector in space, with flow and shock penetration through fluid, plastic, and elastic zones was studied. The original paper and computer program on this topic is presented. Improvements in the program for the study of the formation of a cone of debris are discussed. The truncated apex of the cone is at the hole formed by the penetration of an initially spherical rock through a thin plate. A solution for the penetration of the thin plate was sought.
The results are presented of a study to obtain a computer program for the penetration of a thin plate of aluminum by a sphere of rock. The study was divided into two projects. One project covers the initial impact, the crushing of the sphere of rock, the break up of the aluminum sheet, and the conversion of the sufficiently shock-compressed regions of rock and aluminum into a plasma. The other project considers the ejection of a cone of plasma with entrained particles from the impact zone, its expansion as it traverses a region of free space, and its impact on a stack of paper sheets. The ablation of fragments in penetrating the stack of paper sheets is also considered.
A series of experiments has been performed on the Sandia Hypervelocity Launcher to determine the performance limits of conventional Whipple shields against representative 0.8 g aluminum orbital debris plate-like fragments with velocities of 7 and 10 km/s. Supporting diagnostics include flash X-rays, high speed photography and transient digitizers for timing correlation. Two Whipple shield designs were tested with either a 0.030 cm or a 0.127 cm thick front sheet and a 0.407 cm thick backsheet separated by 30.5 cm. These two designs bracket the ballistic penetration limit curve for protection against these debris simulants for 7 km/s impacts.