Faculty Profiles - AKAHOSHI Yasuhiro

Papers - AKAHOSHI Yasuhiro

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2A02 A New Attempt of Education in Strength of Material (Part 2)

AKAHOSHI Yasuhiro

Proceedings of Annual Conference of Japanese Society for Engineering Education ( Japanese Society for Engineering Education ) 2024 ( 0 ) 94 - 95 2024.01

Estimation of ejecta generation and mitigation measures for large-scale structures on geostationary orbit Reviewed International journal

Kawamoto S., Harada R., Joudoi D., Kimoto Y., Izumiyama T., Akahoshi Y.

Journal of Space Safety Engineering 11 ( 3 ) 507 - 517 2024.01

Study of the effects of projectile strength and density in the asteroid deflection by hypervelocity impact Reviewed International journal

Wakatsuki Y., Akahoshi Y., Koura T., Takahara H.

International Journal of Impact Engineering 180 2023.10

STUDY OF THE EFFECTS OF PROJECTILE STRENGTH AND DENSITY IN THE ASTEROID DEFLECTION BY HYPERVELOCITY IMPACT Reviewed International journal

Wakatsuki Y., Koura T., Akahoshi Y.

Proceedings of the 16th Hypervelocity Impact Symposium, HVIS 2022 2023.01

STUDY ON HYPERVELOCITY IMPACT OF SRM SLAG WITH VOIDS Reviewed International journal

Fujii M., Nitta K., Higashide M., Akahoshi Y., Koura T.

Proceedings of the 16th Hypervelocity Impact Symposium, HVIS 2022 2023.01

A New Attempt of Education in Strength of Material

AKAHOSHI Yasuhiro

Proceedings of Annual Conference of Japanese Society for Engineering Education ( Japanese Society for Engineering Education ) 2021 ( 0 ) 218 - 219 2021.01

Evolution of ISO's space debris mitigation standards Reviewed International journal

Stokes H., Akahoshi Y., Bonnal C., Destefanis R., Gu Y., Kato A., Kutomanov A., LaCroix A., Lemmens S., Lohvynenko A., Oltrogge D., Omaly P., Opiela J., Quan H., Sato K., Sorge M., Tang M.

Journal of Space Safety Engineering 7 ( 3 ) 325 - 331 2020.09

Study of the asteroid orbit change by hypervelocity impact and explosive

KOGA Sota, IKEDA Masaya, YOSHIDA Toi, KOURA Takao, AKAHOSHI Yasuhiro

The Proceedings of Conference of Kyushu Branch ( The Japan Society of Mechanical Engineers ) 2019 ( 0 ) C12 2019.01

Language：English Publishing type：Research paper (conference, symposium, etc.)

Near Earth Objects (NEOs) are asteroids and comets which come close to Earth's orbit each year. So there is a high possibility of impacts for example, in February 2013, an asteroid created an airburst near Chelyabinsk State in Russia, causing an estimated damage of approximately 33M$ and injuring an estimated damage of approximately 1500 people. To avoid asteroid impacts it is necessary to change NEO's orbit. Impacting at a hypervelocity is one of the methods that we consider to change NEO's orbits. Hypervelocity impacts intend to change the orbit by making a spacecraft impacts on the NEO. In our study we examined the orbit change induced by hypervelocity impacts and explosives to further improve the effect. The influence on the orbit by explosives depends on the shape of the crater created by an impactor. Thus we will optimize its shape by making impact tests with a Two Stage Light Gas Gun in order to accelerate impactors with different shapes. As a result, we analyzed of the influence by explosive with AUTODYN from the shape of craters obtained by the experiment and we found that the shape of crater has an optimum condition.

DOI： 10.1299/jsmekyushu.2019.72.C12

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CiNii Research

Other Link： https://ci.nii.ac.jp/naid/130007801936

Evaluation of impact resistance of the CFRP material for aircraft

HAYASHI Taito, AKAHOSHI Yasuhiro, Juhyo Lee, KOURA Takao

The Proceedings of Conference of Kyushu Branch ( The Japan Society of Mechanical Engineers ) 2019 ( 0 ) G14 2019.01

Language：English Publishing type：Research paper (conference, symposium, etc.)

To reduce fuel consumption on airplanes, we need nowadays lighter materials which absolutely need to withstand bird strikes. CFRP (Carbon fiber reinforced plastic) is one of the best materials for this, considering its high strength modulus and low density, but still lacks impact resistance. In this study, we simulated a fragment of aircraft impacting on a fan case in order to develop a CFRP with a better strength and impact resistance than conventional CFRP. For this experiment, we used the gas gun installed in our laboratory, and a rigid rectangle projectile as an impactor. Then, we compared our new lamination structure with conventional CFRP according to the amount of absorbed energy and to the delamination area (internal separation of layers). The amount of energy is obtained by the difference of energy before and after the impact, and the higher the energy absorbed, the more resistant the material is. In the case of the delaminationarea, the smaller it is, the lower the damages are. In new CFRP (called E2-E), the conventional [45, -45] degree layer is changed to a [30, -30] degree layer and a 0 degree layer is added between the 30 and -30 layers. The conventional lamination structure is [(0/45/-45/0)3(45/-45)(0/-45/45/0)3], and the E2-E's lamination structure is [(0/30/0/-30/0)2(30/0/-30)2]s. As a result, for the same amount of energy the CFRP E2-E was not penetrated unlike conventional CFRP. Moreover, the absorbed enegy was higher and the delamination area was smaller, which means the E2-E materialshowed better performances than coventional CFRP.

DOI： 10.1299/jsmekyushu.2019.72.G14

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CiNii Research

Other Link： https://ci.nii.ac.jp/naid/130007801977

Evaluation of durability in harpoon for space debris capture

YOSHIDA Keno, OHMORI Saika, FUJII Satoshi, KOURA Takao, AKAHOSHI Yasuhiro

The Proceedings of Conference of Kyushu Branch ( The Japan Society of Mechanical Engineers ) 2019 ( 0 ) C11 2019.01

Language：English Publishing type：Research paper (conference, symposium, etc.)

One of the promising ways to remove space debris is to attach an electrodynamic tether (EDT) to debris by shooting a harpoon from an active debris removal satellite. There is a possibility for the harpoon to be removed from the surface of debris because of the tensile load of the EDT. The purpose of this research is to evaluate the pull-out force in a novel harpoon designed for the debris capturing system. This new harpoon with a barb is composed of an inner harpoon and an outer harpoon. After the penetration, the outer harpoon is deformed by the inner harpoon and so creates a barb on the tip. Harpoon shooting tests were conducted using a debris capture gun in order to study the impact of the harpoon into the aluminum alloy plate. After firing tests, pull-out tests were conducted by the universal tensile testing machine. During these tests, the harpoon was deformed after the penetration and opened a barb on the tip so the function of barb system could be confirmed. Moreover, the maximum pull-out load the harpoon can handle without being separated from the plate is measured. For some harpoons with the barb system, pull-out load was superior to the non-barb systems. In this way, the efficiency of this design of harpoon is proved, with a maximum loading of 7000 to 16000 N.

DOI： 10.1299/jsmekyushu.2019.72.C11

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CiNii Research

Other Link： https://ci.nii.ac.jp/naid/130007801937

Verification of the revision proposal for ISO11227 considering Ejecta oblique impact test and analysis

HANAKUSA Takafumi, AKAHOSHI Yasuhiro, TAGAMI Shogo, MURATAKE Nanase, KOURA Takao

The Proceedings of Conference of Kyushu Branch ( The Japan Society of Mechanical Engineers ) 2019 ( 0 ) C14 2019.01

Language：English Publishing type：Research paper (conference, symposium, etc.)

At present, Space debris have a lot of problems in the space industry. They are the crush to spacecrafts and making the restriction of orbit in space. ISO 112227 was enacted in 2012 as a measure against microscopic secondary Space debris called Ejecta among space debris. However, this protocol did not take into account oblique impacts of projectiles, and a draft revision is made for the purpose of implementing oblique impact experiments. In this research, as a verification of the revision proposal, a 1 mm diameter projectile simulating micro debris is collided with a two-stage light gas gun at a speed of 5 km.s-1 using a target of A2024-T3, usually used as a spacecraft material. The impact angles are 0 (vertical impact), 45, 60 and 75 degrees. About the evaluation method, it is based on the generation amount of Ejecta and its distribution throughout impact marks. Since the target is a ductile body, the amount of Ejecta generated is small, and so it is difficult to calculate accurate ejecta mass at 60 and 75 degrees. Since the angle also increases the distribution of impact marks, scavenging of Ejecta is insufficient. In order to solve this problem, the way of collecting Ejecta is reviewed in oblique impact experiments.

DOI： 10.1299/jsmekyushu.2019.72.C14

CiNii Article

CiNii Research

Other Link： https://ci.nii.ac.jp/naid/130007801938

Hypervelocity impact phenomena of LPSO-magnesium alloys Reviewed

Nishida M., Kodama F., Hayashi K., Akahoshi Y., Hokamoto K., Kawamura Y.

EPJ Web of Conferences 183 2018.09

International Standardization of Hypervelocity Impact Test Procedure and its Future Plan

AKAHOSHI Yasuhiro

The Proceedings of Conference of Kyushu Branch ( The Japan Society of Mechanical Engineers ) 2018 ( 0 ) J31 2018.01

Study of the Effects of Projectile Shape in the Asteroid Orbit Change by Spacecraft Impact Reviewed International journal

Ikeda M., Tanaka M., Yokoo D., Koura T., Akahoshi Y.

Procedia Engineering 204 138 - 145 2017.01

Lip Formation and Ejecta from LPSO-type Magnesium Alloy Plates in Hypervelocity Impact Reviewed International journal

Nishida M., Ishida K., Kodama F., Hayashi K., Akahoshi Y., Hokamoto K., Mayama T., Yamasaki M., Kawamura Y.

Procedia Engineering 173 65 - 72 2017.01

Ejecta from LPSO-Type Magnesium Alloy Targets in Hypervelocity Impact Experiments Reviewed International journal

Nishida M., Kodama F., Hayashi K., Akahoshi Y., Hokamoto K., Mayama T., Yamasaki M., Kawamura Y.

Procedia Engineering 204 270 - 275 2017.01

Discharge on Solar Array Coupon by Debris Impact Reviewed International journal

Tagami S., Quesada M.R., Koura T., Akahoshi Y.

Procedia Engineering 204 323 - 328 2017.01

Fracture Properties and Ejecta Evaluation of LPSO-Mg Plates in Hypervelocity Impact Experiment

KODAMA Fumiya, NISHIDA Masahiro, ISHIDA Kaito, HAYASHI Koichi, AKAHOSHI Yasuhiro, HOKAMOTO Kazuyuki, MAYAMA Tsuyoshi, YAMAZAKI Michiaki, KAWAMURA Yoshihito

The Proceedings of the Materials and Mechanics Conference ( The Japan Society of Mechanical Engineers ) 2016 ( 0 ) OS01 - 19 2016.01

Language：English Publishing type：Research paper (conference, symposium, etc.)

Long period stacking ordered type magnesium (LPSO-Mg) alloys have low density, excellent mechanical strength and ignition resistance. LPSO-Mg have a great potential as structural materials of satellites. Lip formation and ejecta size were examined when spherical projectiles strikes thin plates made of LPSO-type magnesium alloy at hypervelocity of 5 km/s. Witness plates were placed in front and behind of each target to determine the scattering area. After impact experiments, ejecta were collected from test chamber and lips near penetration hole was observed. Results of LPSO-type magnesium alloy plates were compared with those of aluminum alloy (A6061-T6).

DOI： 10.1299/jsmemm.2016.OS01-19

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CiNii Research

Other Link： https://ci.nii.ac.jp/naid/130007120202

Effects of target temperature on size distribution of ejecta in hypervelocity impact : Toward revision of ISO11227 Reviewed

NISHIDA Masahiro, MIYOKAWA Naoto, KODAMA Fumiya, HAYASHI Koichi, FAURE Pauline, NORIMATSU Koichi, FUJIMURA Yusuke, AKAHOSHI Yasuhiro

Mechanical Engineering Journal ( The Japan Society of Mechanical Engineers ) 3 ( 6 ) 16 - 00148-16-00148 2016.01

Authorship：Last author Language：English Publishing type：Research paper (scientific journal)

As a preliminary study, the effects of target temperature on ejecta size were examined at an impact velocity of 3.5 km/s with the goal of improving the ISO11227. At first, the size of each ejecta collected from test chamber, was examined by the image analysis software using a photograph of each ejecta (direct method). The cumulative number distributions of ejecta size were discussed. The effects of target temperature on ejecta size were small within a predictable range. After that, we compared the ejecta size distribution of the direct method with the results of the international standard method using witness plate (indirect method). The number of ejecta impact craters evaluated by the international standard method was very small at the high temperature. The results of international standard method using witness plate were easily influenced by temperature of target at the high temperature. It is highly possible that the international standard method underestimate the ejecta from target at high temperature.

DOI： 10.1299/mej.16-00148

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Other Link： https://ci.nii.ac.jp/naid/130005250539

OS0106-474 Crater Shape and Ejecta Size Distribution from Hypervelocity Impact of Spherical Projectiles on LPSO Type Magnesium Alloy

ISHIDA Kaito, NISHIDA Masahiro, HAYASHI Koichi, AKAHOSHI Yasuhiro, HOKAMOTO Kazuyuki, KAWAMURA Yoshihito

2015 "OS0106 - 474-1"-"OS0106-474-2" 2015.11

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Papers - AKAHOSHI Yasuhiro