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Yamashita T.,Hyogo Earthquake Engineering Research Center | Miyamura T.,Nihon University | Ohsaki M.,Hiroshima University | Kohiyama M.,Keio University | And 6 more authors.
ECCOMAS Thematic Conference - COMPDYN 2011: 3rd International Conference on Computational Methods in Structural Dynamics and Earthquake Engineering: An IACM Special Interest Conference, Programme | Year: 2011

The project of E-Simulator is under way at Hyogo Earthquake Engineering Research Center (E-Defense), which belongs to National Research Institute for Earth Science and Disaster Prevention (NIED), Japan. E-Defense facilitates the world's largest shaking table. The E-Simulator uses the parallel EF-analysis software package called ADVENTURECluster (ADVC) as a platform, and we carried out elastoplastic seismic response analysis of high-rise building frame with over 70-million DOFs. In this study, we report the results of high-precision FE-analysis for simulation of dynamic collapse behavior of the 4-story steel building frame. The whole frame is discretized into hexahedral elements with linear interpolation functions. In order to improve the accuracy of collapse simulation, a new piecewise linear combined isotropic and kinematic hardening rule is implemented for steel material, and its parameters are identified from the uniaxial material test result. The stud bolts are precisely modeled using multipoint constraints and nonlinear springs. The wire-meshes in the concrete slab are modeled using hexahedral elements. The damping due to plastic energy dissipation of exterior walls is modeled by shear springs between the floors. The accuracy of the model is verified in comparison to the physical test of steel-concrete composite beam subjected to static deformation. It will be shown that elastoplastic dynamic responses of the 4-story frame can be estimated with good accuracy using a high-precision FE-analysis without resort to macro-models such as plastic hinge and composite beam effect.

Yoshimura S.,University of Tokyo | Furuta K.,University of Tokyo | Isobe Y.,Nuclear Fuel Industries | Sagisaka M.,Nuclear Fuel Industries | And 2 more authors.
Transactions of the Atomic Energy Society of Japan | Year: 2010

A number of probabilistic safety assessment (PSA) studies have been conducted to optimize maintenance activities in nuclear power plants from the viewpoint of safety focusing on the risk of core meltdown. However, even a small-scale incident of component, which never causes the core meltdown, resulted in reactor shutdown and economic losses. Accordingly, in addition to the safety analysis focusing on the risk of core meltdown, it is very useful to develop a simulator that can establish maintenance strategies in terms of availability and economic efficiency of nuclear power plants. We have developed an integrated simulator for the maintenance optimization of light water reactors (LWRs). The concept of the simulator is to provide a method for optimizing maintenance activities for representative components and piping systems comprehensively and quantitatively in terms of safety, availability, and economic efficiency (both from cost and profit) under various maintenance strategies including altering inspection frequency and inspection accuracy, conducting sampling inspection, repairs and/or replacements, introducing various maintenance rules, and long-term fuel cycles. In addition, a function of visualization of the simulated results by a divided multidimensional visualization method has also been developed in order to support a decision-making process for optimizing the maintenance activities. © Atomic Energy Society of Japan.

Akiba H.,Allied Engineering Corporation | Ohyama T.,Allied Engineering Corporation | Shibata Y.,Allied Engineering Corporation
Proceedings of the 7th International Conference on Engineering Computational Technology | Year: 2010

This paper shows a domain decomposition method applied to the structural analysis, coarse grid conjugate gradient (CGCG) method and its enhancement. Contrary to the ordinary iterative substructuring method in which the subdomains are considered as substructures, the CGCG method is a fully iterative method in the sense that the decomposed subdomains do not act as substructures. Instead, the domain decomposition is used for the parallel processing, and the global coarse grid motion of the decomposed subdomains is taken into account. The CGCG method shows higher performances than the famous BDD method incorporated into our code, which has the same parallel architecture. In our recent study on the CGCG method, improvements on the algorithms have been made, and these enhancements have been found to bring higher performances than in the previous CGCG version. © 2010 Civil-Comp Press.

Kugimiya T.,Toshiba Corporation | Hirohata K.,Toshiba Corporation | Mukai M.,Toshiba Corporation | Miyake E.,Toshiba Corporation | And 3 more authors.
Proceedings of the ASME InterPack Conference 2009, IPACK2009 | Year: 2010

In this paper, the influence of the interface debonding area between the molding material and the metal frame on the fatigue reliability at die-mount solder joints in plastic IC packages was studied by means of large-scale finite element analyses. There are several factors causing the interface debonding between the molding material and the metal frame, such as manufacturing process, moisture absorption and deformation under field conditions. The debonding will change the structural stiffness of the packages and deformation shape during a thermal or mechanical load. Therefore, it is a critical issue for fatigue reliability. In this paper, three-dimensional large-scale finite element analysis is used for evaluating the influence of the debonding area on fatigue reliability under thermal cycling. The die-mount solder considered is the high-temperature solder 5Sn/95Pb, which is described by the nonlinear kinematic hardening model of Armstrong and Frederick in the finite element constitutive model. From the result of stress analyses, the debonding area has a large influence on inelastic strain, which is related to fatigue reliability. Large-scale finite element analysis is capable of providing useful guidance for structural design and material selection of plastic IC packages. Copyright © 2009 by ASME.

Yoshimura S.,University of Tokyo | Kobayashi K.,Tokyo Electric Power Company | Akiba H.,Allied Engineering Corporation | Suzuki S.,Hitachi - GE Nuclear Energy | Ogino M.,Nagoya University
Transactions of the Atomic Energy Society of Japan | Year: 2012

In this paper, we present the three-dimensional finite element seismic response analysis of the full-scale boiling water reactor BWR5 at the Kashiwazaki-Kariwa Nuclear Power Plant subjected to the Niigata-ken Chuetsu-Oki (NCO) earthquake that occurred on 16 th July 2007. During the earthquake, the automatic shutdown of the reactors was performed successfully. Although the monitored seismic acceleration significantly exceeded the design level, it was found through in-depth investigation that there was no significant damage of the reactor cores or other important systems, structures and components (SSCs). In the seismic design commonly used in Japan, a lumped mass model is employed to evaluate the seismic response of SSCs. Although the lumped mass model has worked well so far for a seismic proof design, more precise methods should be developed to understand response behaviors visually. In the present study, we propose the threedimensional finite element seismic response analysis of the full-scale and precise BWR model in order to directly visualize the dynamic behaviors of this model. Through the comparison of the analysis results, we discuss the characteristics of both models. The stress values were also found to be generally under the design value. ©; 2012 Atomic Energy Society of Japan.

Kohiyama M.,Keio University | Ohsaki M.,Kyoto University | Miyamura T.,Nihon University | Onda K.,Allied Engineering Corporation | And 5 more authors.
9th US National and 10th Canadian Conference on Earthquake Engineering 2010, Including Papers from the 4th International Tsunami Symposium | Year: 2010

The project of E-Simulator is under way at Hyogo Earthquake Engineering Research Center (E-Defense) of National Research Institute of Earth Science and Disaster Prevention (NIED), Japan, which facilitates the world's largest shaking table. The E-Simulator uses the parallel finite element (FE) analysis software package called ADVENTYRECluster (ADVC) as a platform. In this study, we report the results of high-precision FE-analysis for simulation of collapse behavior of the 4-story steel building frame that is the specimen of the full-scale total collapse shaking-table test conducted in September 2007 at E-Defense. It is shown that elastoplastic dynamic responses can be estimated with good accuracy using a high-precision FE-analysis without resort to macro models such as plastic hinge and composite beam effect.

Yamashita T.,Hyogo Prefectural Institute of Technology | Miyamura T.,Japanese University | Akiba H.,Allied Engineering Co. | Kajiwara K.,Hyogo Prefectural Institute of Technology
Transactions of the Japan Society for Computational Engineering and Science | Year: 2013

Recent advancement in parallel computing enables the precise finite element analysis of steel frames using solid elements. However, the finite element models used in the analysis have not been verified sufficiently. In this study, first, static finite element elastic-plastic buckling analyses of a square steel tube column subjected to a prescribed lateral displacement are performed with different meshes in order to verify the analysis model. It is shown that the accuracy and computation time of the analysis depend not only on the number of mesh divisions but also on the aspect ratio of each finite element. Then, dynamic elastic-plastic buckling analyses are performed for different meshes and different time increments. In the dynamic buckling problem, which is a kind of slow dynamics problem, accurate results can be obtained using a fine mesh but with a rather large time increment. © 2013 by the Japan Society for Computational Engineering and Science.

Miyamura T.,Nihon University | Yamashita T.,Hyogo Earthquake Engineering Research Center | Akiba H.,Allied Engineering Corporation | Ohsaki M.,Hiroshima University
Earthquake Engineering and Structural Dynamics | Year: 2015

Dynamic finite element analyses of a four-story steel building frame modeled as a fine mesh of solid elements are performed using E-Simulator, which is a parallel finite element analysis software package for precisely simulating collapse behaviors of civil and building structures. E-Simulator is under development at the National Research Institute for Earth Science and Disaster Prevention (NIED), Japan. A full-scale shake-table test for a four-story frame was conducted using E-Defense at NIED, which is the largest shaking table in the world. A mesh of the entire structure of a four-story frame with approximately 19 million degrees of freedom is constructed using solid elements. The density of the mesh is determined by referring to the results of elastic-plastic buckling analyses of a column of the frame using meshes of different densities. Therefore, the analysis model of the frame is well verified. Seismic response analyses under 60, 100, and 115% excitations of the JR Takatori record of the 1995 Hyogoken-Nanbu earthquake are performed. Note that the simulation does not reproduce the collapse under the 100% excitation of the Takatori record in the E-Defense test. Therefore, simulations for the 115% case are also performed. The results obtained by E-Simulator are compared with those obtained by the E-Defense full-scale test in order to validate the results obtained by E-Simulator. The shear forces and interstory drift angles of the first story obtained by the simulation and the test are in good agreement. Both the response of the entire frame and the local deformation as a result of elastic-plastic buckling are simulated simultaneously using E-Simulator. © 2014 John Wiley & Sons, Ltd.

Yamade Y.,Mizuho Information and Research Institute | Kato C.,University of Tokyo | Yoshimura S.,University of Tokyo | Iida A.,Toyohashi University of Technology | And 4 more authors.
SAE Technical Papers | Year: 2016

A wall-resolving Large Eddy Simulation (LES) has been performed by using up to 40 billion grids with a minimum grid resolution of 0.1 mm for predicting the exterior hydrodynamic pressure fluctuations in the turbulent boundary layers of a test car with simplified geometry. At several sampling points on the car surface, which included a point on the side window, the door panel, and the front fender panel, the computed hydrodynamic pressure fluctuations were compared with those measured by microphones installed on the surface of the car in a wind tunnel, and effects of the grid resolution on the accuracy of the predicted frequency spectra were discussed. The power spectra of the pressure fluctuations computed with 5 billion grid LES agreed reasonably well with those measured in the wind tunnel up to around 2 kHz although they had some discrepancy with the measured ones in the low and middle frequencies. The Dynamic Smagorinsky Model (DSM) was adopted for the subgrid-scale turbulence model of LES while the resulting spatially-filtered Navier-Stokes equations of the incompressible fluid flow were solved by a Finite Element Method. In the second paper of this series of studies, the hydrodynamic pressure fluctuations computed on the car surfaces will be used as the unsteady loading for computing the panel vibration of the test car by using Finite Element Method, and finally the interior acoustical fields will be predicted by solving the Helmholtz equation for sound propagation. The contribution from the external acoustical field to the interior noise, which was not simulated by the present incompressible LES-based approach, was estimated based on the acoustic analogy, and was confirmed to be negligibly small compared with those from the hydrodynamic loading in the present case. © 2016 SAE International.

Iida K.,Suzuki Motor Corporation | Onda K.,Allied Engineering Corporation | Iida A.,Toyohashi University of Technology | Kato C.,University of Tokyo | And 4 more authors.
SAE Technical Papers | Year: 2016

One-way coupled simulation method that combines CFD, structural and acoustical analyses has been developed aiming at predicting the aeroacoustical interior noise for a wide range of frequency between 100 Hz and 4 kHz. Statistical Energy Analysis (SEA) has been widely used for evaluating transmission of sound through a car body and resulting interior sound field. Instead of SEA, we directly computed vibration and sound in order to investigate and understand propagation paths of vibration in a car body and sound fields. As the first step of this approach, we predicted the pressure fluctuations on the external surfaces of a car by computing the unsteady flow around the car. Secondly, the predicted pressure fluctuations were fed to the subsequent structural vibration analysis to predict vibration accelerations on the internal surfaces of the car. Finally, an acoustical analysis was performed to predict sound fields in the cabin by using particle velocities of sound on the interior surfaces of the car, predicted by the structural analysis. To transfer predicted surface data, such as pressure fluctuations, vibration accelerations and particle velocities of sound, from one simulation to another, we adopted a parallel coupling tool. As the second part of our research, this paper presents results of the structural vibration analysis and that of the acoustical analysis, together with those measured by wind tunnel tests. In our research, a light automobile, for which all the interior components were removed and the underfloor shape was simplified, was employed for a case study. The wind tunnel tests were performed with a freestream velocity of 100 km/h. Both the predicted interior surface accelerations and interior noise level agreed well with the measured equivalents up to 2 kHz. Copyright © 2016 SAE International.

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