An F-bar aided edge-based smoothed finite element methods with four-node tetrahedral elements (F-barES-FEM-T4) in large deformation explicit dynamics for nearly incompressible materials is proposed. Because F-barES-FEM-T4 is based on on the standard displacement-based variational formulations, it can be easily applied to dynamic analysis by adding the term of inertia to the static equilibrium equation. Some example analyses of explicit dynamics for simple and complex shapes reveal that the proposed method can suppress volumetric locking and pressure oscillation in dynamic explicit cases as well as in static implicit cases. Meanwhile, these analyses also reveal that the proposed method causes energy divergence in long-term analyses. As the speed of energy divergence can be suppressed by increasing the smoothing level, the proposed method with sufficient smoothing presents good results in relatively short-term analyses.
For large-scale numerical simulations on supercomputers, data transfer and storage present significant efficiency and productivity issues. Therefore, the jointed hierarchical precision compression number-data format (JHPCN-DF) technique was proposed for efficient visualization and analysis of plasma particle-in-cell simulation data. It is also available for lossless and lossy compression with user-defined errors. We implement a lossy compression method of JHPCN-DF in finite element code and evaluate the compression effectiveness and compression data accuracy in linear static and dynamic structural analyses. Our technique achieves the required accuracy, even for dynamic problems, and provides a significant increase in compression performance for variable datasets.
In order to educate teenager internet literacy on social network service, we have developed a Problem Solving Environment to evaluate the literacy-level of their messages on twitter for their teachers and them. We propose a method the system provides effective recognition for their risks. And we adapt the Naive Bayes classifier to evaluation for tweets on Twitter based on pattern-based classifier. In this result, the classification accuracy for word patterns increases from 39.6-57.6% to 68.0-79.9% using Naive Bayes classifier on a set of 3000 training data sets, and users obtain internet literacy skills base on this system.
To enable the prediction of the mechanical degradation of solid oxide fuel cell (SOFC) during operation, we have developed an analysis system for the electrochemical and mechanical coupling phenomena by incorporating general-purpose finite element analysis (FEA) software along with its pre- and post-processing functions and conducted validation analyses to examine its quantitative performance in reproducing the measurement data. The dependencies of material properties on both temperature and oxygen’s chemical potentials are empirically obtained and stored in separate spreadsheets and read into the system so that the actual operation environment can be realized. The thermal and reduction strains calculated in the transient analysis for the potentials are also stored in spreadsheets beforehand and used in the stress analyses to make quantitative evaluation of creep deformations. Through a numerical example, the mathematical model implemented into the developed system has been initially validated in a quantitative way.
A new nonlinear film resistance model and a new nonlinear film growth model in electrodeposition (ED) coating simulation are presented. The new resistance model considers the electric resistance of turbid paint on cathode before the film deposition. The new growth model considers history dependency in the film growth rate varied with current density on cathode when the initial film deposits. The parameters of the new models are identified with a series of simple one-plate ED test data. Some finite element analyses show that the results with the new models are more accurate compared to those with the conventional models.
Manufacturers must provide products that are robust under use by various types of customers. In this study, the quality engineering was used to optimize the shape of the crank-case considering the influence of the error. The oil behavior in the crank-case was calculated by the MPS method. The optimization was conducted using the orthogonal array L18. The design parameters were related to the shape of the crank-case, and the error was the viscosity of the oil and the revolving speed of the crank-shaft. Furthermore, the crank-case was prototyped and the oil temperature in crank-case was measured to validate the calculation result.
Accurate numerical integration technique for a discontinuous integrand by the Delaunay decomposition has been proposed to calculate interactive terms in finite element mesh superposition method (FEMS). In this paper, the high accuracy numerical integration technique for high order local elements with curved surface is proposed. High order elements are divided into segments only with plane boundaries using some additional vertices to deal with hollow domains adequately. The previous proposed technique that is based on grouping of vertices to obtain a tetrahedralization is applied to all segments. In the first example, the performance of the proposed technique is estimated in 2-D analysis. In the second example, the proposed technique is applied to 3-D zooming analysis. In the 3rd example, smooth microstructures is add in VOXEL model using FEMS with the proposed technique.
The quasi-three-dimensional XFEM is applied to damage propagation analyses of CFRP (Carbon Fiber Reinforced Plastics) laminate. Six-node triangular interface element and six-node pentahedral continuum element enriched with Heaviside function are employed to model delamination and matrix crack, respectively. Bi-linear type cohesive zone model is introduced between delamination and/or matrix crack and then implicit static or explicit dynamic method is utilized to solve system equations considering materially nonlinearity. Code verification was performed through DCB, ENF and TCT test specimen analyses and damage propagation analyses of NHT (No Hole Tension) and OHT (Open Hole Tension) test specimens were validated by comparison with experiment results. In addition, computation conditions for explicit dynamic analysis including mass scaling and energy balance, Zig-zag CZM, and threshold parameter of crack shape definition were examined. It was shown that implicit static method using Zig-zag CZM is the most efficient for damage propagation analysis using the proposed method.
There is a trade-off problem between the distance and the repeatability in golf. Our goal is to obtain the pareto solution by formulating the problem as a multi-objective optimization, and to develop the optimal golf shaft for the player. Club speed and body burden were used as indexes for the distance and the repeatability. Finite element method and multibody dynamics were used for the calculation of the club speed and the body burden. Response surface method was applied to get a pareto solution. As an analytical result, it was found out that the optimized shaft increased club speed by 2.2 m/s and decreased the body burden by around 7% compared to the control shaft. The optimized shaft was manufactured and conducted some experiments for validation. As average data of 10 shots, the distance increased by 8 yds and repeatability was improved by 16 yds with the optimal shaft.
The purpose of this study is to develop a snow model emphasizing the splashing phenomenon and the impact force acting on the train surface to ensure safe driving. Snow is assumed to be a Bingham fluid due to its peculiar shear thinning. A Bingham numerical model is proposed by using the Moving Particle Semi-Implicit (MPS) method and tested for collision between a train and snow. As well, verification of this special non-Newtonian fluid is carried out and good agreement is obtained by comparing the MPS numerical result with a reference solution. Furthermore, a collision simulation between train and snow is implemented in which a natural splashing phenomenon occurs by introducing the present Bingham snow model. Finally, the time history of pressure in the foremost area of the train head is analyzed, which can provide a reference for safe train driving.
This study presents a numerical method of snow avalanches. The method is based on a stabilized finite element method in SUPG/PSPG formulations with unstructublack mesh. The flow property of the snow is represented by a Bingham type fluid model; the shear strength is described using a Coulomb’s yield criterion. In order to verify the method, simulations of a model experiment were performed, and simulated run-out distance and impact force were compablack with the experimental results. The method was finally applied to an actual snow avalanche that took place at the foot of the Mount Gassan in 2011. Simulated results reproduced the actual snow avalanche accurately, and it was found the method can represent flow behaviors of snow avalanches even in the complex calculation conditions, such as those containing complex geometry, retaining walls and vegetation.
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