A reactive material double-bumper shield for centimeter sized projectile

https://doi.org/10.1016/j.ijimpeng.2021.104028Get rights and content

Highlights

  • A reactive material double-bumper shield which can effectively shield against centimeter-sized projectiles was presented.

  • The process of projectile impacting on the reactive material double-bumper shield was analyzed.

  • The ballistic limit curve of the reactive material double-bumper shield was obtained.

Abstract

The hypervelocity impact of space debris will cause fatal damage to spacecraft. At present, most of the protective shield structures can only resist the impact of millimeter sized projectiles, and it is very difficult for the protective structure with the finite area density and overall spacing to be impacted by the projectile with the diameter ≥1cm without failure. In this paper, a PTFE (polytetrafluoroethylene)/Al (aluminum) reactive material double-bumper shield for centimeter sized space debris was presented, and the experiments of projectiles with hypervelocity impact on PTFE/Al reactive material double-bumper shields were carried out by using two-stage light-gas gun. The hypervelocity impact characteristics of Aluminum alloy double-bumper shield and PTFE/Al reactive material double-bumper shield were compared by numerical simulation. The ballistic limit curve of the PTFE/Al reactive material double-bumper shield was obtained by experiments and numerical simulations. The PTFE/Al reactive material double-bumper shield can resist the impact of the projectiles with the diameter ≥1cm at the low velocity range, intermediate velocity range, and the high velocity range. The PTFE/Al reactive material double-bumper shield can stop projectiles with 2∼4 times greater mass than the Aluminum alloy double-bumper shield at these impact conditions, and the PTFE/Al reactive material double-bumper shield can provide better protection than the Aluminum alloy double-bumper shield of equivalent weight. Compared with the Nextel/Kevlar Stuffed-Whipple shield, the impact resistance of PTFE/Al reactive materials is not lower than that of Nextel/Kevlar fiber materials.

Introduction

The hypervelocity impact of orbital debris will cause damage to spacecraft, and the Whipple shield [1] and many enhanced shields [2], [3], [4], [5], [6] based on Whipple shield were applied to protect spacecraft from impact of orbital debris. However, most of the protective shield structures can only resist the impact of millimeter sized projectiles. It was very difficult for the protective structure with the finite area density to be impacted by the projectile with the diameter ≥1cm without failure. Compared with the Whipple shield, the double-bumper shield with the same total areal density and overall spacing can provide better protection. The second layer bumper can further shatter the projectile fragments shattered by the first layer bumper, which will lead to projectile being shattered into smaller fragmentations [7,8]. However, the double-bumper shield needs large overall spacing to enhance the protection effectively.

Similar to the double-bumper shield, the stuffed-Whipple shield has two bumpers, and they have the same protection mechanism. Johnson Space Center (JSC) and Marshall Space Flight Center (MSFC) engineers [9,10] developed a low-weight shield system with the smaller overall spacing to enhance the protection of conventional Whipple shield. This shield is the Nextel/Kevlar stuffed-Whipple shield (SW Mod-2), and this shield includes an Al6061 bumper (2mm thickness), a flexible intermediate layer combining Nextel ceramic fabric (6 layers) and Kevlar fabric (6 layers), and an Al2219 rear wall (4.8mm thickness). The overall areal density of the SW Mod-2 shield is 2.7g/cm2, and the overall spacing is 11.4cm. It can be effective against the normal impact of spherical projectile as large as 1cm to 1.5cm with the velocities higher than 4km/s. European Space Agency [9,11] developed Nextel/Kevlar-Epoxy Stuffed-Whipple shield (Columbus SW), and this shield was applied to the Columbus pressurized module of the International Space Station (ISS). In the Columbus SW shield, the bumper is Al6061 (2.5mm), the intermediate layer is flexible intermediate layer combining Nextel ceramic fabric (4 layers) and Kevlar-Epoxy (6mm), and the rear wall is Al2291 (4.8mm). The overall areal density of the Columbus SW shield is 3.2g/cm2, and the overall spacing is 13cm. The shield can against the normal impact of 1.3cm spherical projectile with the velocity of 3km/s and the normal impact of 1.5cm spherical projectile with the velocity of 6.5km/s. Destefanis and Schafer [12] developed a By-layered Al-foam/Kevlar-2D Stuffed-Whipple shield (AB2 Mod) based on the Columbus shield, and this shield has greater overall spacing and higher total area density than JSC and MSFC developed. The protective capability of the AB2 Mod is close to that of Columbus SW.

At present, a variety of materials are used in protective shield structures, such as the aluminium honeycomb [13], ceramic-metal composites [14], fiber materials [15,16], and impedance-graded materials [17]. All of these materials are inert materials, and the mechanism of shattering projectile by the pressure induced by impact is single. Wu and Zhang [18] presented a Whipple shield with PTFE(polytetrafluoroethylene)/Al(aluminum) reactive material as bumper, and the protective capability of Whipple shield was greatly enhanced. PTFE/Al is an impact-induced metastable energetic material. PTFE/Al exhibit inertness in the ambient conditions, and the detonation reaction will be induced under the strong shock load [19], [20], [21], [22]. The detonation reaction occurs only in the impact area due to its non self-sustaining property. The reaction threshold velocity of PTFE/Al is between 100∼200m/s [20,23], PTFE/Al will still react with low reaction rate and low reaction pressure under the low velocity impact load. The reaction rate of PTFE/Al reactive material increases with the increase of impact velocity, and detonation reaction will be induced with rapid and intense reaction rate under the hypervelocity impact. The vibration and shock of spacecraft during transportation and launch are low frequency and low velocity relative to the hypervelocity impact of space debris, which does not induce the reaction of the reactive material. The reactive material bumper can shatter the projectile into smaller, less massive and slower fragments due to the combined effect of impact and detonation reaction [24,25]. In addition, PTFE/Al reactive material bumper will not produce solid fragments because the reaction products are gas. Because the perforation of the reactive material bumper is usually very small [26], the total mass of the reaction products is small. The most of these gas reaction products form debris cloud moving towards the rear wall. As long as the rear wall is not perforated by the debris cloud, the high temperature reaction products will not enter the interior of the spacecraft, and the electronic devices inside the spacecraft will not be damaged. A small part of the reaction products will eject in the direction opposite to the projectile velocity, and the numerical simulation results show that this part of products only accounts for 10% ∼ 20% of all products [24]. This part of the products will eject outward within an angle range. If the impact position is close to the solar panel and electronic devices outside spacecraft, the reaction products may have an influence on it, but since the reverse ejected reaction products are a small amount, the influence on the solar panel and electronic devices is very little.

The yield strength of PTFE/Al reactive material under quasi-static state is about 20MPa [27,28], and this does not meet the overall structural design requirements of spacecraft. However, the latest research shows that the yield strength of reactive material can be greatly increased to more than 200MPa by adding some fiber materials [29,30]. Although this will reduce the energy density of reactive materials, it still makes it possible for the practical application of reactive material as the load-bearing structural parts of spacecraft.

In this paper, a double-bumper shield with the PTFE/Al reactive material as bumpers is presented. The hypervelocity impact characteristics of the PTFE/Al reactive material double-bumper shield were studied by experiments and numerical simulations, and the differences of hypervelocity impact behaviors between the traditional aluminum alloy double-bumper shield and reactive material double-bumper shield were analyzed. According to the experimental and numerical simulation results, the ballistic limit curve (BLC) of the reactive material double-bumper shield was obtained. The PTFE/Al reactive material double-bumper shield can effective against the normal impact of projectile as large as 1cm to 1.5cm with the velocities of 2∼6km/s.

Section snippets

Materials

PTFE/Al is a kind of PTFE matrix composite, which can be fabricated by mold pressing and sintering [31,32]. PTFE powders with average particle size of 3μm were mixed with pure aluminum powders with average particle size of 30μm, and the ratio of PTFE powders to aluminum powders was 73.5/26.5 by weight. The mold with diameter of 110mm was used during the model pressing, and the mixed powers were pressed at 80MPa. The pressure rise rate was 30N/s, and the pressure was maintained for 2 min after

Experimental setup

The hypervelocity impact experiments were carried out by using the two-stage light-gas gun with the launching tube caliber of 30mm, as shown in Fig 2. The light-gas gun used the gas products produced by the combustion reaction of hyperbaric hydrogen and oxygen in the combustion chamber as the driving force, and the combustion chamber was also filled with a certain proportion of nitrogen to increase the driving ability of the light gas gun. In order to simulate the space environment, the target

Simulation setup

In order to study the impact characteristics of the reactive material double-bumper shield, the Smooth Particle Hydrodynamics (SPH) numerical simulation was applied by AUTODYN-2D software. Wu and Guo [18,22] developed the numerical simulation model for hypervelocity impact of reactive material. The Lee-Tarver model was applied to describe the impact-induced reactive behaviors of PTFE/Al reactive material under the hypervelocity impact, and the Johnson-Cook model was applied to express the

Ballistic limit curve

Christiansen [3,33] developed the ballistic limit equation to evaluate the capability of shield structure to resist hypervelocity impact. The ballistic limit curve was divided into three ranges according to the penetration state: the low velocity range (v0vl), intermediate velocity range (vl<v0<vh), and the high velocity range (v0vh).

For v0vl:dc=[(tw(σ/40)0.5+tb)/(0.6(cosθ)3/5ρp0.5v02/3)]18/19

For vl<v0<vh:dc={[(tw(σ/40)0.5+tb)/(1.248ρp0.5cosθ)]18/19(1.75(v0cosθ)/4)}+{[1.071tw2/3ρp1/3ρb1/9S

Conclusion

In this paper, a PTFE/Al reactive material double-bumper shield for centimeter sized space debris was presented, and the experiments of projectiles with hypervelocity impact on PTFE/Al reactive material double-bumper shields were carried out by using two-stage light-gas gun. The impact processes of projectiles on PTFE/Al double-bumper shield and Al2024 double-bumper shield were studied by numerical simulations. After two impacts with the reactive bumpers, the kinetic energy of the projectile

Author contributions

Siyuan Ren: Methodology, Formal analysis, Writing-Original Draft, Writing - Review & Editing

Qingming Zhang: Conceptualization, Methodology, Supervision, Project administration

Qiang Wu: Formal analysis, Writing-Original Draft

RenRong Long: Conceptualization, Project administration, Investigation

Liangfei Gong: Investigation

Yangyu Lu: Investigation

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledge

This work was supported by Civil Aerospace Pre-research Project (D020304) and National Natural Science Foundation of China (11802034).

References (33)

  • B Feng et al.

    A crack-induced initiation mechanism of Al-PTFE under quasi-static compression and the investigation of influencing factors

    Mater Des

    (2016)
  • EL Christiansen et al.

    Ballistic limit equations for spacecraft shielding

    Int J Impact Eng

    (2001)
  • FL. Whipple

    Meteorites and Space travels

    Astronmical J

    (1947)
  • Christiansen El

    Design and performance equations for advanced meteoroid and debris shields

    Int J Impact Eng

    (1993)
  • WP Schonberg et al.

    Spacecraft wall design for increased protection against penetration by orbital debris impacts

    AIAA J

    (1990)
  • EL Christiansen et al.

    Hypervelocity impact testing above 10km/s of advanced orbital debris shields. Shock Compression of Condensed Matter

    AIP Conf Proc

    (1995)
  • Cited by (12)

    • Satellite breakup behaviors and model under the hypervelocity impact and explosion: A review

      2023, Defence Technology
      Citation Excerpt :

      The two-stage light-gas gun of Ernst Mach Institute (EMI) was also used in the study of satellite breakup caused by impact, and the gun can accelerate 3.7 g projectile to the velocity of 1.9 km/s [39,40]. The 30 mm caliber two-stage light-gas gun of Beijing Institute of Technology (BIT) uses the detonation reaction of hydrogen oxygen mixture as the driving force, and the gun can launch 30 g projectile to the velocity of 5.63 km/s or 12 g projectile to the velocity of 8.38 km/s [41,42]. Fragments recovery is a complex and necessary work, and it must be achieved that all generated fragments are collected without any secondary damages to ensure the reliability of the breakup fragment data.

    • Coupled finite element-discrete element method (FEM/DEM) for modelling hypervelocity impacts

      2023, Acta Astronautica
      Citation Excerpt :

      Several numerical approaches are available when modelling HVIs. Smoothed particle hydrodynamics (SPH) is widely used (e.g. [3–6]) because the meshless formulation allows for straightforward handling of the localised, hydrodynamic material behaviour found under such conditions. SPH is therefore suitable for problems where the medium moves like a liquid.

    • Impact resistance mechanism of reactive material bumper for spacecraft Whipple shield: Experiments and numerical simulations

      2022, Aerospace Science and Technology
      Citation Excerpt :

      Ren and Zhang [38] preliminarily verified that the protective capability of PTFE/Al reactive material Whipple shield was higher than that of traditional aluminum alloy, and the debris cloud was experimentally studied. Furthermore, the ballistic limit of the PTFE/Al double-bumper shield was experimentally studied [39]. Although the protective capability of PTFE/Al reactive material Whipple shield has been verified, the interaction process between projectile and reactive bumper has not been analyzed, especially how does shock wave induced by the combined effect of impact and detonation cause projectile fragmentation.

    View all citing articles on Scopus
    View full text