Higashi Hiroshima, Japan
Higashi Hiroshima, Japan

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Ikehara T.,Minamisenju | Tanaka E.,Fukasaku | Nagamura K.,Kagamiyama | Kojima S.,Fukasaku | And 3 more authors.
Applied Mechanics and Materials | Year: 2012

A Closed-Fitting-Type walking assistance device was developed. The combination of a flexible shaft with a worm gear was successfully adopted on this device to simplify its appearance and reduce its size. A hybrid control system on this device controls both torque and angle at the ankle and knee joints. As a result of walking that mounted a Walking Assistance Device to motor paralysis patient, the effect of support and the improvement of postural were achieved. © (2012) Trans Tech Publications, Switzerland.


Tanaka E.,Fukasaku | Ikehara T.,Minamisenju | Sakurai T.,Fukasaku | Suzuki T.,Fukasaku | And 3 more authors.
Applied Mechanics and Materials | Year: 2012

We have developed a prototype for a walking-assistance apparatus that serves as a next-generation vehicle or a movable neuro-rehabilitation training appliance for the elderly or motor palsy patients. Our prototype uses a novel spatial parallel link mechanism with a weight-bearing lift. Flat steps of the apparatus move in parallel with the ground; the apparatus supports the entire leg alignment (including soles of the feet) and assists walking behavior at the ankle, knee, and hip joints simultaneously. To estimate the walking phase of each leg of the equipped person, pressure sensors were attached under the thenar eminence and the heel of the sole and the pressure variation at each sensing point was measured. To determine the direction in which the equipped person is walking, a pressure sensor was attached to the flexible crural link. Motor palsy patients and those with muscle weakness can walk with the assistance of the apparatus. Patients who have ambulation difficulty can also use the apparatus with a weight-bearing lift that we developed. Using the apparatus with the weight-bearing lift prevents stumbling and enables input of walking movement to the brain motor area. The validity of the weight-bearing lift can be confirmed from the results of the measured % maximum voluntary contraction (MVC). © (2012) Trans Tech Publications, Switzerland.


Katahira T.,Kagamiyama | Naka T.,Yuge Shimoyuge | Kohzu M.,Gakuen cho | Yoshida F.,Kagamiyama
Key Engineering Materials | Year: 2013

In the present work, FLDs of AZ31 magnesium alloy sheet for non-proportional strain paths were investigated by performing two-step stretch forming experiments at various forming speeds (3, 30 and 300 mm.min -1) at elevated temperatures of 150, 200 and 250°C. The forming limit strains, both for proportional and non-proportional deformations, increased with temperature rise and with decreasing forming speed. A FLC after a uniaxial pre-strain lies outside of the proportional FLC for a given condition of temperature and forming speed, whereas a biaxially pre-strained FLC lies inside of the proportional FLC. It was found that the accumulated effective plastic strain and the direction of plastic strain increment at the final stage of forming are two major factors that influence the forming limits for non-proportional deformations. © (2013) Trans Tech Publications, Switzerland.


Katahira T.,Kagamiyama | Hosokawa S.,Kagamiyama | Naka T.,Yuge Shimoyuge | Kohzu M.,Gakuen cho | And 2 more authors.
Advanced Materials Research | Year: 2014

Magnesium alloy sheets have a potential to be widely used in many fields of industry due to their excellent lightweight property. Although magnesium alloys have low ductility at the room temperature due to their hexagonal close-packed structure, their formability can be improved at elevated temperatures. Therefore, warm press-forming of magnesium alloy sheets is an attractive technology. The objective of the present work is to investigate the cyclic plasticity behavior of an AZ31 sheet at elevated temperatures by performing cyclic tension-compression experiments. The cyclic deformation mechanism is examined by measuring the crystallographic orientation distributions by means of X-ray diffraction method at each stage of the cyclic deformation. The present findings are summarized as follows: (1) Stress-strain responses of an AZ31 sheet were investigated at various temperatures (R.T, 100, 150 and 200°C) at strain rates of 0.001, 0.01 and 0.05 s-1. The flow stresses were insensitive to the strain rate at the room temperature, however the strain rate dependency of the flow stress becomes dominant at elevated temperatures of over 100 °C. (2) Cyclic plasticity behavior of the sheet at various elevated temperatures (R.T, 100, 150 and 200°C) at strain rates of 0.001, 0.01 and 0.05 s-1 were investigated by performing warm in-plane cyclic compression-tension test. Similarly to the uniaxial tension test, apparent temperature and strain rate dependencies of the flow stress were observed at temperatures of over 100 °C. (3) At the room temperature an unusual cyclic stress-strain curve, which is very different from that of bcc and fcc metals, was observed. From the texture measurement it was found that such a specific stress-strain characteristic is due to its twinning and detwinning deformation mechanism. (4) In contrast, at an elevated temperature of 200°C, the usual cyclic stress-strain response, which is similar to one appearing in most of metallic materials, was observed. This is because the major deformation mechanism at an elevated temperature is the slip, rather than twinning/detwinning, since the CRSS decreases drastically with increasing temperature. © (2014) Trans Tech Publications, Switzerland.


Uemori T.,Takaya Umenobe | Sumikawa S.,Kagamiyama | Tamura S.,Kagamiyama | Yoshida F.,Kagamiyama
Key Engineering Materials | Year: 2013

Aluminum sheet metals have been widely utilized for a light weight construction of automobile. However, these metals still remain one of the difficult materials to predict the accurate final shapes after press forming processes, because of several mechanical weak features such as strong plastic anisotropy of yield stress, large Lankford value, and so on. In order to solve the problems, the present author has developed a new constitutive model. The model can describe accurate non-proportional hardening behaviors of an aluminum sheet metal. In the present research, several experimental procedures were carried out to reveal the mechanical properties of an aluminum sheet under proportional and non-proportional loading. From the comparisons between experimental data and the corresponding calculated results by the proposed constitutive model, the performance of our model was evaluated. The evaluation of some springback analyses were also carried out. The calculated results show good agreements with the corresponding experimental data. © (2013) Trans Tech Publications, Switzerland.


Matsumoto S.,Kinki University | Mitsui S.,Kure National College of Technology | Ohkubo T.,Kagamiyama
WCTE 2014 - World Conference on Timber Engineering, Proceedings | Year: 2014

The joints are very important structural element in timber framed structures. The purpose of this study is to develop the high-strength and high-ductility beam-column joint for timber structure. In this study, steel plate fastened with drift pins and paste the ultraviolet-ray hardening Fiber Reinforced Plastics (FRP) on the surface of the member section. The wood is the anisotropic material of which the strength characteristic greatly differs according to the direction of the fiber. The strength of the fiber direction is high, but the strength of the fiber orthogonal direction is low. Also, the splitting failure is caused in the fiber orthogonal direction, and there is a case in which strength and toughness extremely lower. It is necessary to consider the weak point of such woody material for the case in which the wood is used as a structural element for timber framed structure. It is very important to be ensured the earthquake-proof safety of the building, and prevent a building collapse for the great earthquake. This study reinforces weak point on the strength of woody material by using the ultraviolet-ray hardening FRP. Then, timber framed joint of the high-strength and high ductility is developed as a structural element. In this study, the verification experiment is carried out for the joint element specimens of the large section wood.

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