Masahide Katayama

Design Concept for Local Damage of Concrete Plates Subjected to High Velocity Impact

Local damage of concrete structures, i.e. spalling, scabbing and perforation, would occur when concrete structures are impacted by high velocity projectiles. To propose protective design of concrete structures against high velocity impact, failure mechanism of local damage of concrete plates should be investigated. The authors have studied on failure mechanism of the local damage through impact tests and numerical analyses. This study presents a design concept for the local damage of a concrete plate subjected to high velocity impact. In the design procedure, occurrence of scabbing is judged based on comparison between maximum impact load and scabbing resistant capacity of the concrete plate. Impact load history and penetration depth are calculated using the modified theoretical model, and scabbing resistant capacity is estimated by applying a modified formula for punching shear resistant capacity.

Computer Simulation of a Boeing 747 Passenger Jet Crashing into a Reinforced Concrete Wall

The purpose of this study is aimed at assessing the capabilities to numerically simulate the dynamic phenomenon of a Boeing 747 jetliner impacting against a reinforced concrete wall. The geometry of the numerical model of the jetliner is adjusted to fit the Boeing data which are available publicly. The thickness of the wall is 3 meters and the impact velocity is 300 km/h. Because of the highly nonlinear characteristics of the phenomenon the strain hardening and the strain rate effects are considered for the constitutive models of the jetliner and the concrete. The simulation shows that the concrete wall exhibits no severe damage by the impact under the conditions assumed in the study. Introduction An accident previously considered hypothetical became real when the hijacked Boeing 767 passenger jet crashed into the North Tower of the New York World Trade Center on September 11, 2001. The possibilities of aircraft impacts against infrastructures have been investigated mainly in nuclear industries since 80’s [1], [2] . However, the aircrafts discussed in these studies were not commercial jetliners but military jet fighters such as an F-4 Phantom. In the present paper, a three-dimensional computer simulation of the impact of a Boeing 747 passenger jet against a reinforced concrete wall has been conducted using the AUTODYN ® -3D computer program [3] . The B747 is almost 15 times as heavy as the F-4. All the components of the jetliner of our numerical model, namely, the fuselage, the wings and the engines are modeled by shell elements. The concrete is modeled by solid elements and the reinforcement by beam elements. The impacts between these elements are examined by a contact capability. An eroding slideline capability is utilized to prevent mesh tangling. The Johnson-Cook constitutive equations [4] are applied to aluminum, and the RHT model [5] to the concrete. The numerical results were discussed over the crushing behavior of the B747 and the impact force loaded on the wall. Recommendations for future studies are presented to improve the accuracy of the simulation. Finite Element Model The AUTODYN ® -3D utilizes various numerical solvers such as finite element, finite difference, finite volume and smooth particle hydrodynamics (SPH) methods. In the present study shell elements are used for the jetliner. Hexahedral solid elements are used for modeling the concrete wall, and beam elements for the reinforcements. Boeing 747 jetliner The geometry of the jetliner is created first by the general-purpose TrueGrid mesh generation computer program [6] . Then the obtained geometry is imported into the AUTODYN finite element model as shown in Fig.1. The overall length is 70.5 meters and the Materials Science Forum Online: 2004-09-15 ISSN: 1662-9752, Vols. 465-466, pp 73-78 doi:10.4028/www.scientific.net/MSF.465-466.73

Introduction of coupled thermomechanical equations into a hydrocode

Abstract A computational procedure to solve the coupled thermomechanical equations is developed by means of a three-dimensional explicit Lagrangian hydrocode. The basic field equations including thermal effects are first presented. Then, after a brief overview of the original PEC method [1] to solve the coupled equations in an explicit manner, it is extended to a general purpose hydrocode. The numerical procedures are listed in a step-by-step sequence. Finally, a sample computation is conducted for a cylinder impact test and compared with the corresponding experimental result.

A Basic Study on Shock Resistant Design for Explosion Pit

The mechanism of damage on the structure of an explosion pit which belongs to the Institute of Pulsed Power Science, Kumamoto University is investigated. Investigated is the mechanism of damage on the structure of an explosion pit which belongs to the Institute of Pulsed Power Science, Kumamoto University. Here, three-dimensional model with square opening (door) is used to simulate by numerical simulation. The numerical result with the actual egg-type model implies that firstly the cracks occurred at the corners of the door and grew larger. In addition, the numerically simulated results with a spherical form model are also demonstrated to study on optimizing the design of an explosion pit.

Numerical analysis on the damage of the explosion pit at Kumamoto University

This study investigates effects of impact action and its damage to structures. Here, we utilized as our object of study the explosion pit located at the Shock Wave and Condensed Matter Research Center of Kumamoto University. We conducted numerical analysis on damage to the explosion pit to elucidate how small cracks on the surface of reinforced concrete of the pit arose. Herein, ANSYS AUTODYN refers to the numerical analysis software utilized.

Numerical Analysis Method for the RC Structures Subjected to Aircraft Impact and HE Detonation

This paper proposes and demonstrates a numerical simulation method suitable to analyze the local damage and dynamic response of the structures composed of the reinforced concrete (RC) and/or the geological materials subjected to the severe impulsive loading by the aircraft impact and the high explosive detonation. After the brief description about the numerical simulation method, the former part of this work attests that the present method has an enough accuracy to simulate the dynamic behavior of the RC structures subjected to the impulsive loading, through the comparison of the numerical analysis results with those of reference experiments. In the latter part of this work, three-dimensional numerical simulation results are investigated which were performed by using the basically the same analysis method as applied in the former part, but for much more complicated physical system. Through the discussion on the numerical simulation results the effectiveness of the present method is demonstrated from the viewpoint of the high-velocity impact safety, the explosion safety, and the structural integrity evaluation.