Experimental study on pressure resistance performance of the plastic housing for the underwater robot system
The underwater housing is used to protect the electronic parts of the underwater robot system from water and pressure. The housing made of a metal material is widely used, but the weight is heavy and the price is expensive. So in recent years the housing of plastic material that is inexpensive and lightweight is being used in shallow water depth. In this paper, we have obtained the pressure resistance performance in several plastic housing specimens by the high pressure experiments. In the experiments result, we know the pressure resistance performance of the oil filled housing specimen better than other specimens.
Pressure test of a pressure vessel with glass dome and cylinder of other material
Glass dome is a very good component for pressure vessel. A sphere by two domes becomes very strong pressure vessel. However, combination with cylindrical housing of the other material is not good. Young's modulus of glass is 64GPa and is very low compared with conventional steel, titanium alloy, aluminum alloy or ceramics, which means that a glass dome shrinks larger than a cylinder made of the other material. The glass dome is very strong against outer pressure when it shrinks evenly, but when it shrinks unevenly by any reasons, tensile stress or stress concentration on edge of the dome may come out, which leads to crack and to collapse of the glass dome. The author tested a glass dome with ceramic cylinder, but it collapsed at a little higher pressure than the planned operational pressure. Analysis showed that the collapse was due to the uneven shrinkage of glass dome. In order to avoid uneven shrinkage of glass dome, the friction at the rim of glass dome with the supporting structure must be zero or very small. However, conventional low-friction material like Teflon sheet is not good for this purpose because of the plastic flow by the large contact stress. Thus, the author introduced a special coating technology, Diamond-Like Carbon (DLC) coating. This coating requires very smooth surface with Ra<0.02μm, and the coated surface becomes very hard like diamond, which makes the friction coefficient as 0.05∼0.15 at the manufacturer's data. The pressure test was conducted for a pressure vessel of a steel cylinder with two glass dome caps. The glass domes were supported by DLC-coated seats at both ends of the steel cylinder. The maximum test pressure was targeted to 110% of the operational pressure, but the pressure vessel collapsed at a little lower pressure than the planned operational pressure. However, the analysis of this collapse gave us new knowledge on the structural strength of the pressure vessel with glass dome. This paper discusses about the design philosophy of a pressure vessel with glass dome and a cylinder.
Column Axial Load Effects on Performance of Panel Zone in Welded-Flange-Plate Connections
In this study the effects of different levels of column axial load on seismic performance of Welded Flange Plate (WFP) connections with different panel zone strength are presented. Finite element method was used to do this investigation and reliability of the modelling method was verified by comparison with experimental available records in documents. Fifteen sub-assemblages of WFP connections were generated by means of ABAQUS software. The aim was to enhance the knowledge about the consequence of column axial load level on cyclic behaviour and fracture potential of the connections with different panel zone strength for external joints in Steel Moment Resisting Frames (SMRFs). Results showed that cyclic behaviour including hysteresis loops and energy dissipation were not affected significantly by increasing column axial load regardless of the panel zone strength. It was also found that increase of the fracture potential due to increase in column axial load became less pronounced when the panel zone strength was decreased.