On Protection of Freedom’s Solar Dynamic Radiator From the Orbital Debris Environment: Part II—Further Testing and Analysis

1992 ◽  
Vol 114 (3) ◽  
pp. 142-149 ◽  
Author(s):  
Jennifer L. Rhatigan ◽  
Eric L. Christiansen ◽  
Michael L. Fleming

Recent progress to better understand the environmental threat of micrometeoroid and space debris to the solar dynamic radiator for the Space Station Freedom power system is reported. The objective was to define a design which would perform to survivability requirements over the expected lifetime of the radiator. A previous paper described the approach developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeoroid and space debris impacts. Preliminary analyses were presented to quantify the solar dynamic radiator survivability. These included the type of particle and particle population expected to defeat the radiator bumpering. Results of preliminary hypervelocity impact (HVI) testing performed on radiator panel samples were also presented. This paper presents results of a more extensive test program undertaken to further define the response of the solar dynamic radiator to HVI. Tests were conducted on representative radiator panels (under ambient, nonoperating conditions) over a range of particle size, particle density, impact angle, and impact velocity. Target parameters were also varied. Data indicate that analytical penetration predictions are conservative (i.e., pessimistic) for the specific configuration of the solar dynamic radiator. Test results are used to define more rigorously the solar dynamic radiator reliability with respect to HVI. Test data, analyses, and survivability results are presented.

1992 ◽  
Vol 114 (3) ◽  
pp. 135-141
Author(s):  
Jennifer L. Rhatigan ◽  
Eric L. Christiansen ◽  
Michael L. Fleming

A great deal of experimentation and analysis has been performed to quantify penetration thresholds of components which will experience orbital debris impacts. Penetration has been found to depend upon mission-specific parameters such as orbital altitude, inclination, and orientation of the component; and upon component specific parameters such as material, density, and the geometry particular to its shielding. Experimental results are highly dependent upon shield configuration and cannot be extrapolated with confidence to alternate shield configurations. Also, current experimental capabilities are limited to velocities which only approach the lower limit of predicted orbital debris velocities. Therefore, prediction of the penetrating particle size for a particular component having a complex geometry remains highly uncertain. This paper describes the approach developed to assess on-orbit survivability of the solar dynamic radiator due to micrometeroid and space debris impacts. Preliminary analyses are presented to quantify the solar dynamic radiator survivability, and include the type of particle and particle population expected to defeat the radiator bumpering (i.e., penetrate a fluid flow tube). Results of preliminary hypervelocity impact testing performed on radiator panel samples (in the 6 to 7 km/sec velocity range) are also presented. Plans for further analyses and testing are discussed. These efforts are expected to lead to a radiator design which will perform to Space Station Freedom requirements over the expected lifetime.


2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
B. Aïssa ◽  
K. Tagziria ◽  
E. Haddad ◽  
W. Jamroz ◽  
J. Loiseau ◽  
...  

The presence in the space of micrometeoroids and orbital debris, particularly in the lower earth orbit, presents a continuous hazard to orbiting satellites, spacecrafts, and the international space station. Space debris includes all nonfunctional, man-made objects and fragments. As the population of debris continues to grow, the probability of collisions that could lead to potential damage will consequently increase. This work addresses a short review of the space debris “challenge” and reports on our recent results obtained on the application of self-healing composite materials on impacted composite structures used in space. Self healing materials were blends of microcapsules containing mainly various combinations of a 5-ethylidene-2-norbornene (5E2N) and dicyclopentadiene (DCPD) monomers, reacted with ruthenium Grubbs' catalyst. The self healing materials were then mixed with a resin epoxy and single-walled carbon nanotubes (SWNTs) using vacuum centrifuging technique. The obtained nanocomposites were infused into the layers of woven carbon fibers reinforced polymer (CFRP). The CFRP specimens were then subjected to hypervelocity impact conditions—prevailing in the space environment—using a home-made implosion-driven hypervelocity launcher. The different self-healing capabilities were determined and the SWNT contribution was discussed with respect to the experimental parameters.


Author(s):  
Igor Ye. Telitchev

The present paper is devoted to analysis of burst conditions of thin-walled cylindrical pressure vessels subjected to hypervelocity impact of space debris particles. Two types of gas-filled pressure vessels onboard the International Space Station were considered: inhabited or laboratory pressurized modules and onboard system vessels with a gas under high pressure. The central concern of this study is to determine the border between simple perforation and catastrophic fracture of gas-filled pressure vessels of both types under hypervelocity impact. Non-linear fracture mechanics techniques were used to analyze and predict whether a vessel perforation will lead to mere leakage of gas, or whether unstable crack propagation will occur that could lead to catastrophic fracture of the vessel. Damage patterns and mechanisms leading to unstable crack growth are discussed. A model of fracture of an impact damaged pressure vessel is presented. A developed model was successfully applied to the simulation of experimental results obtained at Ernst-Mach-Institute (Germany).


Author(s):  
P.V. Prosuntsov ◽  
A.A. Alekseev ◽  
E.O. Zherebtsova

The growth in the number of space debris, especially small-size debris undetectable by radars, urges the development of protective equipment for the crucial satellites and space station. Passive multilayer shields are the most effective means of protection. As the shields are big, it makes sense to make them out of flexible composite materials that allow them to be deployed in orbit. The article determines the loads acting on the composite load-bearing frame of the trap for small-size debris during impact. For a rational choice of the structural trap layout and optimization of its design parameters it is critical to know these loads. The hypervelocity impact of the projectile on the shield was modeled in the Altair Radioss software package using a combined model based on the Smoothed Particle Hydrodynamic (SPH) method and mesh finite elements. The simulation of the shield penetration at various locations was carried out. For each simulation case, a time history of the reaction force in the attachment point of the protective shield to the load-bearing frame was determined. It was shown that the maximum load of about 2000 N acts for around 6 milliseconds on the joint closest to the impact point for the debris projectile size of 10 mm and velocity of 2 km/s.


2012 ◽  
Vol 525-526 ◽  
pp. 397-400
Author(s):  
Gong Shun Guan ◽  
Dong Dong Pu ◽  
Yue Ha

A series of hypervelocity impact tests on stainless steel mesh/aluminum plate multi-shock shield were practiced with a two-stage light gas gun facility. Impact velocity was approximately 4km/s. The diameter of projectiles was 6.4mm. The impact angle was 0°. The fragmentation and dispersal of hypervelocity particle against stainless steel mesh bumper varying with mesh opening size and the wire diameter were investigated. It was found that the mesh wall position, diameter of wire, separation distance arrangement and mesh opening had high influence on the hypervelocity impact characteristic of stainless steel mesh/aluminum plate multi-shock shields. When the stainless steel mesh wall was located in the first wall site of the bumper it did not help comminuting and decelerating projectile. When the stainless steel mesh wall was located in the last wall site of the bumper, it could help dispersing debris clouds, reducing the damage of the rear wall. Optimized design idea of stainless steel mesh/aluminum plate multi-shock shields was suggested.


2010 ◽  
Vol 452-453 ◽  
pp. 385-388
Author(s):  
Bin Jia ◽  
Gao Jian Liao ◽  
Hai Peng Gong ◽  
Bao Jun Pang

All spacecrafts in earth orbit are subject to hypervelocity impact by micro-meteoroids and space debris, which can in turn lead to significant damage and catastrophic failure of spacecraft. Porous volcano rock was adopted as one of micro-meteoroid material due to their similar physical and geometric features. Two-stage light gas gun experiments were carried out for a 6mm diameter volcano rock projectile impact on an Al-Whipple shield within the speed range from 1 km/s to 3 km/s. An ANSYS/LS-DYNA software was employed and justified by experimental results, in which a porous geometrical model was established for volcano rock projectile. The higher speed range was extended from 3 km/s to 10 km/s by numerical simulation. The results of experiments and numerical simulation indicated that major damage on rear wall of the Whipple shield impacted by volcano rock projectile is caused by the fragments of bumper of the shield, which is different from that of aluminum projectile. And 5.5km/s is the critical speed of a 6mm diameter volcano rock projectile impact on the Whipple shield investigated.


2001 ◽  
Author(s):  
Lisa M. Oravecz-Simpkins ◽  
Indrek S. Wichman

Abstract A Hele-Shaw apparatus that produced spreading diffusion flames in the near extinction limit was designed and constructed. A scaling analysis was used to determine the maximum test section height for which effects of gravity could be neglected. Preliminary results showed that this apparatus could be used to produce flame instabilities which resemble drop tower test results from NASA [1,2] and other diffusion flame instability studies [3,4,5,6]. Therefore, the Hele-Shaw apparatus is useful for studying flames in a simulated low gravity environment. Additional unstable behaviors seen in the device, such as flame pulsing and spreading blue cusps, not in the NASA testing further supported the need for investigations during longer microgravity times on the International Space Station. The initial testing was only used to gain an observable region of unstable flames. Further studies will be directed at explaining and quantifying specific behaviors with test conditions.


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