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Journal Articles

Evaluation of local damage to reinforced concrete panels subjected to oblique impact by soft missile

Nishida, Akemi; Kang, Z.; Nagai, Minoru*; Tsubota, Haruji; Li, Y.

Nuclear Engineering and Design, 350, p.116 - 127, 2019/08

Many empirical formulas have been proposed for evaluating local damage to reinforced concrete structures caused by impacts of rigid missiles. Most of these formulas have been derived based on tests involving impact normal to target structures. Thus far, few tests with oblique impact onto target structures have been carried out. As a final goal of this research, we aim to propose a new formula for evaluating the local damage caused by oblique impact based on previous experimental and simulation results. In this study, we perform simulation analyses for evaluating the local damage to reinforced concrete panels subjected to oblique impacts with various angle by soft missiles under various impact velocities using a simulation method that was validated using the results of previous impact experiments. In this paper, the investigated results and obtained knowledges from them are shown.

Journal Articles

Impact assessment on local damage to reinforced concrete panels by different projectiles; Impact behavior for projectiles with hemispherical nose shape

Kang, Z.; Nagai, Minoru*; Nishida, Akemi; Tsubota, Haruji; Li, Y.

Proceedings of 25th International Conference on Structural Mechanics in Reactor Technology (SMiRT-25) (USB Flash Drive), 10 Pages, 2019/08

Many empirical formulae have been proposed for evaluating the local damage to reinforced concrete (RC) structures caused by rigid projectile impact. The majority of these formulae aim at impact tests perpendicular to target structures, while few impact tests oblique to the target structure have been studied. The final objective of this study is to propose a new formula for evaluating the local damage to RC structures caused by oblique impact based on past experimental and simulation results. Up to now, we validated the analytical method by comparison with the experimental results and conduct the simulation analysis of impact assessment on RC panel by rigid/soft projectile with flat nose shape using the validated approach. In the part 1 of this paper, the same analytical method is used to simulate the local damage to RC panels caused by oblique impact of rigid/soft projectile with hemispherical nose shape. The results associated with penetration depth of RC structure, energy contribution ratio, etc. are presented.

Journal Articles

Simulation analysis on local damage to reinforced concrete panels subjected to oblique impact by different projectiles, 1; Comparison of impact behavior for rigid projectiles with flat and hemispherical nose shape

Kang, Z.; Nagai, Minoru*; Nishida, Akemi; Tsubota, Haruji; Li, Y.

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 9 Pages, 2019/05

Many empirical formulae have been proposed for evaluating the local damage to reinforced concrete (RC) structures caused by rigid projectile impact. The majority of these formulae aim at impact tests perpendicular to target structures, while few impact tests oblique to the target structure have been studied. The final objective of this study is to propose a new formula for evaluating the local damage to RC structures caused by oblique impact based on past experimental and simulation results. The finite element code LS-DYNA R7.1.2 is used to perform the numerical analysis by adopting Lagrangian finite elements and explicit time integration. So far, we validated the analytical method by comparison with the experimental results and conduct the simulation analysis of impact assessment on RC panel by rigid/soft projectile with flat nose shape using the validated approach. Results of reduction coefficient with respect to rigid/soft projectile and impact angle were obtained. Therefore, in this study, we focus on the impact problems caused by rigid projectile with hemispherical nose shape. The same analytical method is used to simulate the local damage to RC panels caused by oblique impact of rigid projectile with hemispherical nose shape. The results associated with penetration depth of RC structure, energy contribution ratio, etc. are presented. According to the comparison analysis of results of local damage to RC structure by rigid projectiles with flat and hemispherical nose shape, the influence of different nose shapes of rigid projectile on the local damage of RC panels caused by oblique impact is investigated.

Journal Articles

Simulation analysis on local damage to reinforced concrete panels subjected to oblique impact by different projectiles, 2; Comparison of impact behavior for soft projectiles with flat and hemispherical nose shape

Nagai, Minoru*; Kang, Z.; Nishida, Akemi; Tsubota, Haruji; Li, Y.

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 8 Pages, 2019/05

In this study, the final purpose is to propose a new formula for evaluating the local damage caused by oblique impact based on past experimental results and previous research achievements. Up to now, we validated the analytical method by comparison with the experimental results and conducted simulation analysis associated with impact assessment on RC panel by soft/rigid projectile with flat nose shape using the validated approach. In the part 1 of this study, the same procedure of our previous work is followed to investigate the local damage to RC panel caused by rigid projectile with flat and hemispherical nose shape. In the part 2, we focus on the comparison analysis of simulation results of local damage to RC panel subjected to oblique impact by soft missile with flat and hemispherical nose shape. The structural damage of RC panel and projectiles, energy contribution ratio, etc. is studied for each case. The results indicate the difference of nose shape of projectile is of great importance to influence the penetration depth generated by oblique impact of soft projectile.

Journal Articles

Evaluation of local damage to reinforced concrete panels subjected to oblique impact; Simulation analysis for evaluating perforation phenomena caused by oblique impact of deformable projectiles

Nishida, Akemi; Nagai, Minoru*; Tsubota, Haruji; Li, Y.

Mechanical Engineering Journal (Internet), 5(5), p.18-00087_1 - 18-00087_21, 2018/08

To date, oblique impact has not been studied and few experimental data on the local damage of reinforced concrete (RC) panels exist for oblique impact of deformable projectiles. The final purpose of this study is to propose a new formula for evaluating the local damage to reinforced concrete structures caused by oblique impact based on past experimental results and simulation results. As the first step of this final purpose, we validate the analytical method by comparison with the experimental results and simulate the damage caused by oblique impact using the validated method. First, we analyze and simulate the local damage of RC panel caused by a deformable projectile owing to an impact test normal to the target structure to verify the validity of the simulation analysis. Next, we perform simulation analyses for evaluating the perforation of RC panel due to oblique impact by the deformable projectile and present the results. Various response characteristics and perforation mechanisms to be the basis of examination of oblique impact evaluation were clarified in this paper.

Journal Articles

Evaluation of local damage to reinforced concrete panels subjected to oblique impact of rigid and soft missiles

Nishida, Akemi; Nagai, Minoru*; Tsubota, Haruji; Li, Y.

Proceedings of 26th International Conference on Nuclear Engineering (ICONE-26) (Internet), 8 Pages, 2018/07

Many empirical formulas have been proposed for evaluating local damage to reinforced concrete (RC) structures caused by impacts of rigid missiles. Most of these formulas have been derived based on impact tests normal to the target structures. Up to now, few impact tests oblique to the target structures have been carried out. This study has been conducted with the purpose of proposing a new formula for evaluating the local damage caused by oblique impacts based on previous experimental and simulation results. In this paper, the results of simulation analyses for evaluating the local damage to a RC panel subjected to normal and oblique impacts by rigid and soft missiles, by using the simulation method that was validated using the results of previous impact experiments. Based on the results of these simulation analyses, the effects of the rigidity of the missile as well as the impact angle on the local damage to the target structures are clarified.

Oral presentation

Ordering of frustrated spin systems coupled to lattice and charge degrees of freedom; Neutron scattering investigations

Kakurai, Kazuhisa; Matsuda, Masaaki; Ishii, Yoshinobu; Nagai, Satoshi*; Ikeda, Naoshi*; Kito, Hijiri*; Igawa, Naoki; Soda, Minoru*; Yasui, Yukio*; Moyoshi, Taketo*; et al.

no journal, , 

Two examples of neutron scattering investigations on the magnetic ordering process in frustrated spin system coupled to lattice and charge degrees of freedom are presented, in both cases leading to a short-ranged magnetic ground state. (1) In LuFe$$_{2}$$O$$_{4}$$ the Fe ions are arranged to form hexagonal double layers along the rhombohedral unique axis. Detailed investigation of the ordering process revealed a magnetic ground state with short-range order along the stacking direction. (2) YBaCo$$_{4}$$O$$_{7}$$ has a structure with alternating stacking of a kagome-like and triangular lattice formed of CoO$$_{4}$$ tetrahedra. Although the Co moments do not exhibit a long range ordering down to 10K, strong diffuse scattering due to the short-range ordering of the moments on the kagome-like and triangular lattices are observed.

Oral presentation

Production of medical radioisotope $$^{90}$$Y with fast neutrons by the Be(p,n) reaction

Takeda, Shinsaku; Tsukada, Kazuaki; Sato, Tetsuya; Asai, Masato; Nagai, Yasuki; Sakama, Minoru*

no journal, , 

no abstracts in English

Oral presentation

A Study for evaluating local damage to reinforced concrete panels subjected to oblique impact; Simulation analysis for investigating differences of impact effect by projectiles with different nose shape

Kang, Z.; Nagai, Minoru*; Nishida, Akemi; Tsubota, Haruji

no journal, , 

Many empirical formulae have been proposed for evaluating the local damage to reinforced concrete structures caused by rigid projectile impact. Most of these formulae have been derived based on impact tests perpendicular to target structures. To date, few impact tests oblique to target structures have been carried out. Therefore, in this series of study, the final objective is to explore a new formula for evaluating the local damage caused by oblique impact based on reference solutions and our research achievements. In this work, we present the simulation results for evaluating the local damage to reinforced concrete panels caused by normal and oblique impact of rigid and deformable projectiles with cylinder and hemisphere nose shape. Based on the analytical results, we investigate the differences of impact response characteristics between normal and oblique impact by two types of projectile with different nose shape.

Oral presentation

Evaluation on impact response of RC structures subjected to projectile impact

Nishida, Akemi; Nagai, Minoru*; Kang, Z.; Tsubota, Haruji

no journal, , 

In order to contribute to the evaluation of influence of projectile impact to the interior component of nuclear facility, we have started research with purpose of grasping the properties of shock wave propagation in nuclear building and elucidating the impact response behavior of the structure. We conducted some impact response analysis and compared the results with the existing experimental data related to the RC panels subjected to projectile impact to confirm the validity of 3D FE model and numerical evaluation method. Then, the impact response of RC structure regarded as the wall structure, etc., of nuclear building was analyzed numerically using the validated 3D FE model and numerical evaluation method. In this paper, the influence of different stiffness of projectile on the impact response behavior of RC structure was investigated through the impact response analysis and the obtained knowledge from the results are presented.

Oral presentation

A Study for evaluating local damage to reinforced concrete structures subjected to oblique impact; Simulation analysis for investigating differences of impact effect by missiles with different noses

Kang, Z.; Nishida, Akemi; Nagai, Minoru*; Tsubota, Haruji

no journal, , 

Many empirical formulas have been proposed for evaluating local damage to reinforced concrete (RC) structures caused by impacts of missile. Most of these formulas have been derived based on impact tests perpendicular to the target structures for the rigid missiles. Up to now, few impact tests oblique to the target structures have been carried out. This study has been conducted with the purpose of proposing new formula for evaluating the local damage caused by oblique impacts for soft missiles based on previous experimental and simulation results. In this paper, the results of simulation analyses for evaluating the local damage to a RC Structure subjected to normal and oblique impacts by missiles, by using the simulation method that was validated using the results of previous impact experiments. Based on the results of these simulation analyses, the effects of the tip shape of the missiles as well as the impact angle on the local damage to the target structures are examined.

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