Scholarly article on topic 'Response of a Wire Probe Antenna Subjected to Hyper-velocity Impacts'

Response of a Wire Probe Antenna Subjected to Hyper-velocity Impacts Academic research paper on "Materials engineering"

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{"Orbital Debris" / "Hydrocode AUTODYN" / "Two-Stage Light Gas Gun" / "Numerical simulation" / spacecraft}

Abstract of research paper on Materials engineering, author of scientific article — Kumi Nitta, Masumi Higashide, Atsuhi Takeba, Masahide Katayama

Abstract We investigated the effect of hypervelocity impacts of micrometeoroids and small-scale orbital space debris (M/OD) on space structures by comparing numerical simulation results obtained using the AUTODYN-3D hydrocode with the results of experiments using a two-stage light gas gun. We compared numerical simulations with experimental results and investigated the response of a Wire Probe anTenna (WPT) wire subjected to high-velocity impacts. We show the response of the WPT wire hypervelocity impacts from 2 km/s up to 15 km/s. We also verified the Ballistic limit curve of WPT wire is shown the downside line.

Academic research paper on topic "Response of a Wire Probe Antenna Subjected to Hyper-velocity Impacts"

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Engineering

Procedía Engineering 103 (2015) 450 - 457

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The 13th Hypervelocity Impact Symposium

Response of a Wire Probe Antenna Subjected to Hyper-Velocity Impacts

Kumi Nittaa*, Masumi Higashideb, Atsuhi Takebac, and Masahide Katayamac

a Institute of Space and Astronautical Science, JAXA, 3-1-1 Yoshinodai, Chuo-ku, Sagamihara-shi, Kanagawa, Japa, b Aerospace Research and Development Directorate, JAXA, Chofu Aerospace Center, 7-44-1 Jindaiji Higashi-machi, Chofu-shi, Tokyo, Japan c Science and Engineering Systems Division, ITOCHU Techno-Solutions, Kasumigaseki Bldg., 3-2-5, Kasumigaseki, Chiyoda-ku, Tokyo, Japan

Abstract

We investigated the effect of hypervelocity impacts of micrometeoroids and small-scale orbital space debris (M/OD) on space structures by comparing numerical simulation results obtained using the AUTODYN-3D hydrocode with the results of experiments using a two-stage light gas gun. We compared numerical simulations with experimental results and investigated the response of a Wire Probe anTenna (WPT) wire subjected to high-velocity impacts. We show the response of the WPT wire hypervelocity impacts from 2 km/s up to 15 km/s. We also verified the Ballistic limit curve of WPT wire is shown the downside line. © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of the Curators of the University of Missouri On behalf of the Missouri University of Science and Technology Keywords: Orbital Debris, Hydrocode AUTODYN, Two-Stage Light Gas Gun, Numerical simulation, spacecraft

Nomenclature

ue Impact velocity (km/s) t thickness of plate (mm) D Diameter of Projectile (mm) d_Diameter of wire (mm)

1. Introduction

To develop Japanese spacecraft design guidelines to protect satellites from a certain degree of micrometeoroid and small-scale orbital space debris (M/OD) impacts [1], a working group formed of members of JAXA, spacecraft manufacturers, experts and researchers in the field of hypervelocity impacts was established to investigate the effects of M/OD impacts on satellite critical parts and bumpers by hypervelocity impact (HVI) tests and analysis. The knowledge acquired is now being reflected in the spacecraft design guidelines. As part of this effort, we investigated the response of a Wire Probe anTenna (WPT) wire subjected to high-velocity impacts.

The object of our study was the WPT of the Energization and Radiation in Geospace (ERG) satellite, shown in figure 1, which is being developed as a science satellite by the Institute of Space and Astronautical Science (ISAS)/Japan Aerospace Exploration Agency (JAXA) [2]. Comprehensive observations of plasma, particles, fields, and waves are important for

* Kumi Nitta. Tel.:+81-50-3362-7996; fax: +81-42-759-8456. E-mail address: nitta.kumi@jaxa.jp.

1877-7058 © 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Peer-review under responsibility of the Curators of the University of Missouri On behalf of the Missouri University of Science and Technology doi:10.1016/j.proeng.2015.04.059

understanding the cross-energy coupling for relativistic electron accelerations and dynamics of space storms. ERG will conduct measurements such as phase space density, generation of plasma waves, and accelerations of relativistic electrons, particularly near the equator. The satellite will be launched around the declining phase of solar cycle 24 (~2015-2016) and its nominal mission life is planned to be longer than one year. It is designed to be Sun-oriented and spin-stabilized with a rotation rate of 7.5 rpm (a period of 8 s). The designed apogee altitude is 4.5 RE (L ~5.5 at the equatorial plane), the perigee altitude is ~300 km and the planned orbital inclination is 31°. This orbit will not only give many opportunities to make equatorial observations but will also allow off-equator observations which are will reveal the propagation of plasma waves from the equator. The WPT will measure the electric field component. It consists of two pairs of wire dipole antennas made of stainless steel conductors covered with a polyimide sheath which measure ~32 m tip-to-tip. These are shown as the prominent cross-shaped wires in figure 1.

Since the velocities of M/OD in orbit are beyond the reach of current experimental capabilities, numerical simulations appear to be the best tool to determine the expected level of damage generated by M/OD on the structural components and instruments of a spacecraft, with the simulation results validated by gas-gun impact tests. In the following, we compare and discuss results of numerical simulations using the ANSYS AUTODYN hydrocode and corresponding impact tests from the viewpoint of assessing the protection of satellites from M/OD hypervelocity impacts. The material models used in the numerical simulations to enable the assessment of phenomena corresponding to a wide range of impact velocities, including shock-induced vaporization, are also discussed.

Figure 1. Energization and Radiation in Geospace (ERG) satellite

2. Numerical analysis method - material models

2.1 Hydrocode

Numerical simulations were performed using the ANSYS AUTODYN hydrocode. As with almost all hydrocodes, the material model in ANSYS AUTODYN consists of three parts: i) an equation of state (E.O.S.) describing the relationships between pressure, density and internal energy (not temperature), ii) a material strength model that expresses constitutive relations of solid materials, and iii) a failure or fracture model. While a failure model for solid materials is typically used, it can also incorporate spalling (fracture by negative pressure) of liquid materials. In spite of their name, therefore, hydrocodes are formulated to simulate the highly dynamic and non-linear behavior of materials not only in the liquid phase but also in the solid and gas phases, and sometimes even the plasma state can be simulated approximately by use of an appropriate E.O.S.

2.2 Projectiles

Orbital space debris is composed of artificial objects which have been created through human activities in near-Earth space since the launch of Sputnik I. The average density of space debris is considered to be 2.8-4.7 g/cm3 for objects smaller than 10 mm, while the relative impact velocity of orbital space debris in low Earth orbit (LEO) is theoretically limited to approximately 16 km/s. In this assessment the space debris material is assumed to be aluminum alloy, SS304 or alumina. The propellant used in solid rocket motors (SRM) contains about 18% aluminum by weight, and these motors eject alumina particles from |im-order dust up to cm-order slugs into Earth orbit.

In our study, the Johnson-Holuquist II model [4] is adapted to simulate alumina. The material model includes an equation of state ("pressure"), a constitutive ("strength") model and a fracture or failure ("damage") model. The Steinberg-Guinan strength model [5] was applied to alumina.

2.3 Targets

The targets tested and simulated numerically in this assessment are stainless wire covered with polyimide-sheet which compose the main part of the ERG satellite's WPT. The Tillotson equation of state [6] was applied to materials that would be subjected to extremely severe physical conditions because it takes into account shock-induced vaporization. The Steinberg-Guinan strength model [5] was applied to ductile materials: wire in case of projectile velocities under 10 km/s.

Figure 2. Two-stage light-gas gun at ISAS/JAXA

3. Experimental facilities

Experiments were carried out using a two-stage light-gas gun installed at ISAS/JAXA, shown in figure 2. This gas gun can accelerate a 0.2 g spherical projectile up to 7 km/s. The projectiles impact a target in a test chamber evacuated to a pressure of around 0.1 Pa. The spherical projectile is initially covered with a cylindrical polycarbonate sabot with a diameter of 7.1 mm and a length of 10.5 mm. This guides the spherical projectile in the helium driving gas during acceleration and detaches from the projectile after sufficient velocity is attained. To simulate M/ODs, we used spherical alumina projectiles with diameters ranging from 0.1 mm to 1 mm, with impact velocities of 2-15 km/s.

4. Results and Discussion

4.1 Experimental and Computational configuration

We obtained numerical simulation results using AUTODYN-3D(6), which is used for impact analysis of complex physical systems including fluid and solid materials. Projectiles impact a target of stainless wire covered with a polyimide sheath that comprises the main part of the WPT. Projectiles to simulate M/OD's are 0.04 mm to 0.15 mm of alumina with 2-15 km/s impact velocities. Projectiles and harness cables are modeled on the Lagrange solver.

Figure 3 shows a schematic of a WPT and figure 4 shows cross-sectional views. Seven conducting wires are treated as a single electrical core and three cores are coupled transversely and stacked in a trilaminar structure with corrected density and matched total mass conductor. The corresponding analytical model is shown in figure 5. The thickness of the polyimide sheath is 0.125 mm and the average total diameter of the core is 0.18 mm. In the impact tests, the length of each harness cable is 10 mm and each edge is set in a 20 N tension condition.

Figure 3. Wire Probe Antenna schematic

(a) Actual shape (b) Numerical set-up

Figure 4. Cross-sectional views of WPT wire cable

Figure 6. Photographs of the experimental set-up.

(a) Two-projectile impact scar.

| 0.12

£ 0.1

o 0.08

o 0.06

"S 0.04 E

□ 0.02 0

0 5 10 15 20

Impact Velocity [km/s]

Figure 8. Comparison of numerical simulations and impact tests

4.2. Hypervelocity Impact Results

The accuracy of the numerical simulation was validated by comparing the computed results with those of the gas gun impact tests. Figure 6 shows photographs of the experimental set-up and Figure 7 shows two impact test results. Figure 8 compares numerical simulations with corresponding impact test cases. NO GO and GO show a not be cut and be cut, respectively. As the impact velocity increases, the ballistic limit of the wire become progressively smaller. The particle diameter was 0.125 mm and the particle velocity was 5.9 km/s. This value is smaller than experimental results.

(b) Single-projectile impact scar. Figure 7. Experimental Results

• □ A • GO:Numerical O NO GO : Numerical □ NO GO:Experimental

« •

w » • •

o o • (""1 o

4.3. Gap Effect

To explain this discrepancy between simulation and hypervelocity impact tests, we need consider gap effects between the conductor and polyimide sheath. We investigated gap effects numerically using a simple set-up shown in figure 9. Figure 10 show a typical numerical result.

Figure 11 summarises the simulation results comparing penetration depths achieved in the target for cases with no gap and a small 2.5mm gap. The figure shows that a small gap increases the ballistic limit by at least 50%. We therefore suppose that the difference between numerical and impact test results of the WPT wire is due to a small gap between the core conductor and sheath present in the physical wires that was not incorporated in the numerical model.

Figure 11. Summary of the numerical simulation results of Gap effect

5. Summary

To assess the structural integrity of spacecraft subjected to the threat of hypervelocity impacts by space debris, a numerical method was proposed mainly from the viewpoint of a material model suitable for extremely severe physical conditions: high pressure, temperature, strain, and strain rate, sometimes accompanied by shock-induced vaporization.

The results of numerical simulations adopting these material models were compared with hypervelocity impact tests using a two-stage light-gas gun, and examples of the impacts on a Wire Probe anTenna (WPT) wire were shown. Although only the results using the Lagragian method were discussed in this paper because of limitations of space, it has been demonstrated that the numerical analysis is able to effectively simulate the overall corresponding impact test results.

We showed the analysis of the response a WPT wire to hypervelocity impacts from 2 km/s to 15 km/s. We also verified that the ballistic limit of a Wire Probe anTenna (WPT) wire becomes progressively smaller as impact velocity increases. This is smaller than experimental results because of the effect of a gap between the conductor and polyimide sheath in the actual WPT wires which was not modeled in the numerical studies. In future we will study the actual shape in numerical investigations and continue to extend the experiments.

Acknowledgements

The experiments were conducted and supported by the Space Plasma Laboratory, ISAS, and JAXA. This research was also supported by the JAXA design guideline Working Group 3.

References

[1] JAXA: Space Debris Protection Design Manual, JERG-2-144-HB001, 2014.

[2] Y. Miyoshi, T. Ono, et al. (Eds.): The Energization and Radiation in Geospace (ERG) Project, Dynamics of the Earth's Radiation Belts and Inner Magnetosphere Published Online: 28 MAR 2013, pp 103-116.

[3] Integrity assessment of the spacecraft subjected to the hypervelocity impact by ceramic and metal projectiles simulating space debris and

micrometeoroids. Materials Science and Engineering B 173 (2010) pp.148-154.

[4] G.R. Johnson, T.J. Holmquist, in: S.C. Schmidt, et al. (Eds.), Proceedings of the High-Pressure Science and Technology-1993 AIP Conf. Proc. No. 309,

AIP, New York (1994) pp. 981-984.

[5] D.J. Steinberg, S.G. Cochran, M.W. Guinan: A constitutive model for metals applicable at high-strain rate, J. Appl. Phys. 51 (1980) pp.1498-1504.

[6] J.H. Tillotson: Metallic equations of state for hypervelocity impact. GA-3216, General Atomic, CA, July 1962.

[7]Chocron, I.S., T.T. Kirchdoerfer, and C.J. Freitas: Modeling of Fabric Impact with High Speed Imaging and Nickel-chromium Wires Validation. the 26th International Ballistics Symposium, Miami, Florida, September 2011.

[8] Jex, D. W.; Adkinson, A. B.; English, J. E.; Linebaugh, C. E: Hypervelocity impact testing of cables, NASA-TN-D-7178, M-450, 1973