Fumikazu Miyasaka

Novel Soft Actuator Using Magnetorheological Elastomer

This paper describes a novel soft actuator using a magnetorheological elastomer. First, the material characteristics in the magnetization process and major contributing factors to magnetization of the magnetic elastomer are shown. Second, an actuator using a magnetorheological elastomer combined with an embedded electromagnet is proposed. The magnetic circuit when a current is applied is described and its operating principle is explained. Finally, the static and dynamic motions and dynamic stress of the actuator are determined by an experimental prototype and measurement setup.

Development of numerical simulation model for FSW employing particle method

Abstract The friction stir welding (FSW) has been used widely in the field of industry. Numerical analysis models for FSW also have been developed and there are many papers about it. In these papers, the most frequently used method is finite element method or finite difference method. However, by employing these methods, it is difficult or troublesome to calculate the advective term both for momentum and temperature. It is also difficult to calculate the big deformation of the material. Moreover, complex process is required to analyse the dissimilar joining with respect to dealing with substance transfer. In this paper, to avoid these difficulties or troublesome processes, particle method is adopted for dissimilar FSW simulation. In particle method, advective term, substance transfer and surface deformation are calculated automatically mainly because that Lagrangian approach is used. Performing some of analysis for FSW, the effectivity of this method is verified.

Numerical analysis of transitional behavior of ferrofluid employing MPS method and FEM

This paper proposes a coupled method of finite-element method (FEM) and moving particle semi-implicit (MPS) method in order to analyze the spike shape of ferrofluid. In this method, magnetic field equation is calculated by FEM and fluid equation is calculated by MPS method.

Mathematical modelling of metal active gas arc welding

Abstract A feasibility study has been conducted to determine whether mathematical models can be used for the numerical simulation of metal active gas (MAG) arc welding. In the present work, a three-dimensional, nonstationary thermal model for fillet welding is developed. The transient temperature distribution in the base metal is numerically analysed to estimate the molten pool size using a finite difference model based on the heat flow equation, and the theoretical configuration of the molten pool is calculated, taking account of the balance of gravity, surface tension, and arc pressure. The developed model can be applied to various welding processes such as multipass welding, lap welding, and welding with torch oscillation. To evaluate the validity of the model analysis, the calculated results are compared with experimental results for MAG welding. Good correspondence is demonstrated between experiment and calculation.

Numerical analysis of electromagnetic levitation of molten metal employing MPS method and FEM

This paper proposes a coupled method of 3D-FEM (finite element method) and MPS (moving particle semi-implicit) method for analyzing the electromagnetic levitation of a molten metal. In this method, the magnetic field equation is calculated by FEM and fluid motion equation of a molten metal is calculated by MPS method. To verify the effectiveness of this method, it is applied to analysis of the behavior of molten metal in electromagnetic levitation.

Numerical Analysis of Cold Crucible Induction Melting Employing FEM and MPS Method

This paper proposes a coupled method of 3-D finite element method (FEM) and moving particle semi-implicit (MPS) method for the analysis of cold crucible induction melting. In this method, the magnetic field is calculated by FEM and the fluid motion equation of the molten metal and the thermal distribution in the molten metal are calculated by the MPS method. In this paper, the phase transformation of the metal is not considered. The effectiveness of this method is verified through the analysis of the molten metal behavior in the crucible.

Study on Analysis Method for Ferrofluid

In this paper, we study a new analysis method to calculate the shape of ferrofluid spikes. The shape of a ferrofluid is influenced by the magnetic force, surface force, and gravity. Therefore, the electromagnetic field equation is coupled with Navier-Stokes equation employing the moving particle semi-implicit (MPS) and the finite-element method (FEM). This paper describes the analysis algorithm of coupled method, and the comparison of calculated and measured results.

Development of circumferential TIG welding process model: a simulation model for welding of pipe and plate

Abstract It is useful to develop a numerical model for various welding positions in order to understand welding phenomena. Welding simulation models for a particular application could help in offline robot programming and online robot control. The objective of this study was to develop a tungsten inert gas (TIG) welding simulation model for various workpieces of different shapes. The present model may be easily applied to several workpiece configurations. This article deals with a model for circumferential welding of a pipe to a plate of mild steel, and aluminium alloys. The calculated results clarify that a homogeneous weld is hardly obtained at a fixed pipe welding position due to gravity, and that weld bead shape varies sensitively with wall thickness in pipe to plate welding. It is concluded that the model proposed in this article is useful to simply simulate TIG welding and provides a powerful means to estimate the optimum process parameters in welding practice.

Numerical Analysis of Negative Ion by Electrostatic Atomization Employing FEM and MPS Method

This paper proposes a coupled method of 3-D finite element method (FEM) and Moving Particle Semi-implicit (MPS) method for the analysis of a negative ion that is produced by electrostatic atomization. In this method, the electric field is calculated by FEM and the fluid motion equation of a drop of water is calculated by the MPS method. The validity of this analysis method is verified by comparison with an experiment.

Analysis of the Disintegration of Charged Droplets Employing Boundary Element Method and Particle Method

It is well known that an initially charged droplet disintegrates repeatedly into several tiny sibling droplets and one parent droplet if the charge exceeds a certain value defined by the Rayleigh Limit. Many researchers have experimentally verified this phenomenon in their works. However, it is difficult to estimate the number, charge and mass of the sibling droplets because the sizes of the droplets are generally very small. In this paper, a new coupled analysis method for the disintegration of dielectric charged droplets employing boundary element method (BEM) and particle method is proposed. The behavior of the droplet during disintegration is analyzed by means of this method.