Senda T.,Kyushu University |
Shimada H.,Kyushu University |
Sasaoka T.,Kyushu University |
Matsui K.,Kyushu University |
And 3 more authors.
30th International No-Dig Conference and Exhibition 2012, No-Dig Sao Paulo 2012 | Year: 2012
Lubrication can effectively reduce necessary thrust for over-cutting if a discrete layer of the lubricant is maintained between the pipe and the excavated soil. The lubricant must be designed to form a layer in the surrounding soil, be pressurized to overcome underground water pressure and stabilize the over-cutting area. The lubricant should fill the complete over-cutting area to minimize surface settlement. However, it has been clarified that for a commercial lubricant to be effective, the ingredients such as sodium and potassium should be eliminated. As a result, for a lubricant not to lose its function as a support against the overburdening pressure of an over-cutting area (hereinafter referred to as tail void) and to enable a reduction in thrust, it is necessary to develop a better quality lubricant that can overcome these problems as soon as possible. From this perspective, a lubricating material comprised of a mixture of surfactant and fly ash was developed. This report focuses attention on minimizing soil deformation. In particular, to stabilize the layer in tail void between the pipe and the excavated soil and to examine the characteristics of material attributes to avoid reduction in thrust, a variety of experiments were performed using both traditional lubricating materials and a new material mixed with fly ash.
Mori N.,University of Toyama |
Uetani Y.,Toyama Prefectural University |
Dohi M.,Sankyo Material Co. |
Matsuda K.,University of Toyama |
Ikeno S.,University of Toyama
Advanced Materials Research | Year: 2012
Rheo-extrusion of hypereutectic Al-14.8%Si-4.5%Cu-1.1%Mg (in mass%) alloy which is considerably difficult to hot-extrude was tried using semi-solid slurry with fine solid granules and almost finely dispersed primary Si particles, made by a newly developed rotor process. Trials of rheo-extrusion at the constant extrusion ratio of 36 using this semi-solid slurry were carried out at the different conditions of the extrusion temperature and the ram speeds ranging from 520 to 560°C and from 5 to 20mm/s, respectively. Under the all rheo-extrusion conditions, this semi-solid slurry could easily be rheo-extruded to the round bars of 6mm diameter with sound surface at much lower extrusion force than that of hot-extrusion at very low extrusion ratio. In addition, the characteristic age-hardening behavior which is thought to be essential for the rheo-extrusion process has been found out, namely the peak hardness values of aged bars rheo-extruded at 520 and 540°C were considerably higher, 30HV at maximum, than that of a gravity casting. © (2012) Trans Tech Publications, Switzerland.
Shiozawa K.,Fukui University of Technology |
Kitajima J.,University of Toyama |
Kaminashi T.,Nissan Chemical Industries Ltd. |
Murai T.,Sankyo Tateyama Holdings Inc. |
Takahashi T.,Sankyo Material Co.
Procedia Engineering | Year: 2011
To evaluate fatigue deformation behavior and fatigue life of extruded magnesium alloy, total strain-controlled and stress-controlled low-cycle fatigue test of three extruded magnesium alloys, AZ31, AZ61 and AZ80, were performed in ambient atmosphere at room temperature using smooth round bar specimen. Mean tensile stress during total strain-controlled fatigue process and mean compressive strain during stress-controlled fatigue process appeared due to asymmetry of yield stress between tension and compression. The values of mean stress and mean strain appeared on three alloys were associated with the ratio of compressive yield stress to tensile one, which resulted in mechanical twinning in the compressive phase. Fatigue criteria proposed previously considering the mean stress effect were evaluated in terms of fatigue life predictions based on the experimental results. Also, an energy-based model taken into account of plastic and elastic energy density was discussed to predict the fatigue lives obtained from total strain-and stress-controlled fatigue experiments. © 2011 Published by Elsevier Ltd.
Sankyo Material Co. | Date: 2005-07-14
Uchida H.,University of Hyogo |
Hanaki S.,University of Hyogo |
Nakatani M.,University of Hyogo |
Tanaka Y.,Nissan Motor Co. |
And 3 more authors.
18th International Corrosion Congress 2011 | Year: 2011
Stress corrosion cracking (SCC) of magnesium alloys in distilled water and 0.004∼4wt% sodium chloride (NaCl) solutions at 298K was studied by slow strain rate technique. As the optimum conditions of AZ61 alloy, the SCC test in 0.004wt% NaCl solution at strain rate of 8.33x10 -6s -1 was selected for the evaluation of cracking susceptibility. The influences of dissolved oxygen and potential on the SCC susceptibility were also studied successfully. For AZ61 and AZ80 alloys, the SCC susceptibility increases slightly with a decrease of grain size and amount of precipitate (βphase: Mg 17Al 12) respectively. The SCC susceptibility of AZ10, AZ31, AZ61, AZ80 and AZ91 alloys increases with an increase of aluminum content. Under the potential-controlled conditions, the AZ61 alloy is highly susceptible to SCC at the anodic potential range close to the corrosion potential (nearly -1.5V vs. SCE), which lies in the potential range of hydrogen evolution. Furthermore, many cracks exhibit transgranular and they are characterized by quasi-cleavage appearance. Results suggest that the SCC of magnesium alloy is due to hydrogen embrittlement and anodic dissolution of the alloy caused by the presence of chloride ions.