Numerical calculation of tensile test using a dumbbell-shaped in thickness direction specimen

This study is the product of a tensile test of a uniaxial tensile specimen having a thinner test section than parallel section, which is a tensile test piece with a dumbbell shape in the thickness direction, fabricated by means of cutting as a preliminary experiment and an evaluation of the mechanical properties of the tensile specimen. In the tensile test, we compared the tensile properties of the dumbbell-shaped in thickness direction tensile specimen with those of conventional tensile specimens. In addition, we analyzed the states of stress and strain in the tensile specimens during a tensile test by using the finite element method

FEM analysis on the deformation behavior of flange portion during early stage in deep drawing of dúplex embossed sheet metal

Duplex embossed sheet metals are very useful due to their high rigidity. Furthermore, it is very interesting that the periodic configurations given by embossing brings a new macroscopic feature into a sheet metal. In this study, in order to confirm the effect of only sub-macroscopic structure, which was the configuration given to sheet metal by duplex embossing process, the material was set to isotropy, and FEM simulation was carried out to investigate about the deformation ehavior of flange portion during the early stage in deep drawing of duplex embossed sheet

FE analysis on the influence of width direction deformation on springback control in v-bending by sheet forging

There have some problems in the press engineering. One of the most representative phenomena is springback. Traditionally, a series of empirical methods were used to obtain target bending angle. However, such methods are relied on the ability and experience of engineer. Therefore, the control of springback is important. According to the viewpoint of plastic processing, it is considered that springback could be controlled by sheet forging method which was added after V-bending process used a punch with a single lump-punch. On the other hand, warp would occur in air bending process when the ratio of width to thickness is relatively small. So, it is considered that width direction deformation would affect springback control to some extent in case of warp is occurred. In this study, V-bending and continuous forging processes were conducted used FE analysis. From the analytical results, occurrence of warp was found. Next, model of these processes in consideration of warp was re-modified. Finally, it was found that the springback was controlled to some extent derived from width direction deformation

N-Body Nuclear Forces at Short Distances in Holographic QCD

We provide a calculation of N-body (N>2) nucleon interactions at short distances in holographic QCD. In the Sakai-Sugimoto model of large N_c massless QCD, N baryons are described by N Yang-Mills instantons in 5 spacetime dimensions. We compute a classical short distance interaction hamiltonian for N 'tHooft instantons. This corresponds to N baryons sharing identical classical spins and isospins. We find that genuine N-body nuclear forces turn out to vanish for N>2, at the leading order. This suggests that classical N-body forces are always suppressed compared with 2-body forces.Comment: 4 page

Development of Grousers with a Tactile Sensor for Wheels of Lunar Exploration Rovers to Measure Sinkage

This paper presents a grouser developed for the wheels of lunar exploration rovers to measure sinkage. The wheels, which are intended to traverse loose soil such as lunar regolith, contain grousers that transfer thrust to the wheels and thus to the body of the rover. The interaction between the wheel (with grousers) and the loose soil can be described using a kinematic model. When traversing loose soil, the wheel sinks into the soil, which necessitates knowledge of the entrance angle needed in order to avoid this problem. If the entrance angle is known, the sinkage can be measured in real time before adverse conditions occur. Because of the importance and usefulness of detecting the entrance angle of the wheel, we herein propose a grouser with an embedded tactile sensor. A strain gauge on the surface of the grousers serves as the tactile sensor. In order to confirm the precision of the proposed grouser, we have performed tests on a rigid surface and loose soil surfaces.ArticleINTERNATIONAL JOURNAL OF ADVANCED ROBOTIC SYSTEMS. 11:49 (2014)journal articl

Effect of blank dimension on formability of forging blank consisting of two metals

We established aforging analysis method for a blank consisting of two metals. In this study, we evaluated the effect of the blank dimensions on the formability of a blank using this analysis method. The analysis results were compared with forging analysis results using just astainless steel pipe as the blank. In both numerical analyses, we used stainless steel pipes with inside diameters of 7 mm and 10 mm. A verification experiment was conducted using the same conditions as these numerical analyses, and we confirmed that the result was the same as in the analyses.Also, we focused on the equivalent stress distribution. We confirmed that the blank iseffective in forming hollow products

Fundamental FEM analysis on tensile deformation of the sheet metal embossed on both sides of the plane

In this study, the tensile test of the embossed sheet was conducted and the tensile deformation behavior is experimentally investigated. Also, in this study, the finite-element method (FEM) analysis on tensile deformation of sheet metals embossed on both side of the plane was also carried out. Fundamental tensile deformation behavior of the embossed sheet was investigated and the relationships between deformation mechanism and apparent mechanical properties are considered

Autonomous Navigation, Guidance and Control of Small Electric Helicopter

In this study, we design an autonomous navigation, guidance and control system for a small electric helicopter. Only small, light-weight, and inaccurate sensors can be used for the control of small helicopters because of the payload limitation. To overcome the problem of inaccurate sensors, a composite navigation system is designed. The designed navigation system enables us to precisely obtain the position and velocity of the helicopter. A guidance and control system is designed for stabilizing the helicopter at an arbitrary point in three-dimensional space. In particular, a novel and simple guidance system is designed using the combination of optimal control theory and quaternion kinematics. The designs of the study are validated experimentally, and the experimental results verify the efficiency of our navigation, guidance and control system for a small electric helicopter.ArticleINTERNATIONAL JOURNAL OF ADVANCED ROBOTIC SYSTEMS. 10:54 (2013)journal articl