ステンレス鋼薄肉パイプ溶接継手部の力学性状に関する研究 : 軽量ステンレス鋼構造に関する研究 その3

This article presents the results of the analysis of changes in the surface topography of AISI 321 (1.4541) thin-walled stainless steel tubes in single-pass Floating-Plug Drawing (FPD) process. Experimental tests were carried out with variable drawing speed (1, 2, 3, 4, 6, and 10 m/min) and different angles of floating plug (11.3°, 13° and 14°). Wisura DSO7010 (Fuchs Oil) lubricant was used in the experiments. Mean roughness Ra and ten point height of irregularities Rz were adopted as surface quality indicators. Roughness parameters were measured independently on the inner and outer surfaces of thin-walled tubes. Analysis of variance was used to analyse the relationship between process parameters (drawing speed and angle of floating plug) and surface roughness of tubes. A decrease in the values of both analyzed roughness parameters was observed as a result of the drawing process. The FPD process significantly improves the inner surface quality of AISI 321 thin-walled stainless steel tubes. The mean roughness value tends to increase with increasing drawing speed, while the angle of the floating-plug has no significant effect on the mean roughness Ra.

The connecting pipe in solar hot water system is made by TIG welding of thin-walled stainless steel and copper. As the welding of stainless steel and copper belongs to dissimilar metal welding and their physical properties are very different, thus the welding of them is difficult and it is likely to cause a variety of defects in the welding process. In this paper, ANSYS software is used to simulate the welding process of stainless steel and copper, and the temperature distributions in the welding process are obtained. The results show that: as the heat transferring of copper is faster than stainless steel, the temperature field distribution of thin-walled stainless steel and copper tubes in the welding process is extremely uneven. As a result, the melting degrees on both sides in the welding seam are inconsistent, which may cause poor forming of weld seam. The results provide references and theoretical basis for the welding technology of dissimilar materials.

The Lithium Blanket Module (LBM) is an approximately 80×80×80 cm cubic module, representative of a helium-cooled lithium oxide fusion reactor blanket module, that will be installed on the TFTR (Tokamak Fusion Test Reactor) in late 1986. The principal objective of the LBM Program is to perform a series of neutron transport and tritium-breeding measurements throughout the LBM when it is exposed to the TFTR toroidal fusion neutron source, and to compare these data with the predictions of Monte Carlo (MCNP) neutronics codes. The LBM consists of 920 2.5-cm diameter breeder rods constructed of lithium oxide (Li2O) pellets housed in thin-walled stainless steel tubes. Procedures for mass-producing 25,000 Li2O pellets with satisfactory reproducibility were developed using purified Li2O powder, and fabrication of all the breeder rods was completed in early 1985. Tritium assay methods were investigated experimentally using both small lithium metal samples and LBM-type pellets. This work demonstrated that the thermal extraction method will be satisfactory for accurate evaluation of the minute concentrations of tritium expected in the LBM pellets (0.1–1 nCi/g).

Compressive behavior of CFDST columns: Effects of thin-walled inner steel tubes

This paper presents experimental and numerical investigations on the structural performance of six steel tube-encased concrete (SC) columns confined by bolted thin-walled circular steel tubes. All specimens were circular columns with a 300 mm diameter, incorporating an encased circular steel tube of 200 mm in outer diameter. Reversed cyclic lateral force and constant axial compression were applied to these specimens. Key experimental parameters included axial load ratio, presence of infilled concrete and the rank of the encased steel tube. Test results demonstrated that confinement by thin-walled circular steel tubes ensured sufficient deformation capacity up to 0.06 rad drift for SC columns with FB-rank and higher encased steel tube, even without concrete infilled and under high axial compression. Test results also indicated that infilling concrete into the FC-rank encased steel tube enhanced the deformability up to 0.06 rad drift. Parallel to the experimental work, a simple evaluation method for the ultimate flexural strength of the SC column was proposed, and a numerical analysis was conducted to predict the overall structural behavior of the SC columns. Both calculated strength and numerical prediction showed close agreement with experimental results.

Experimental investigation of thin-walled concrete-filled steel tube columns with reinforced lattice angle

For the sake of solving sustainability issues and analyzing the complicated service force states, eccentric compression experiments on self-compacting concrete-filled thin-walled medium-length steel tube columns with a circular cross-section were carried out in the present study. Thereafter, the influence of the eccentric ratios and the wall thickness factors on the mechanical behavior and failure characteristics of both the eccentrically loaded and axially loaded columns was comprehensively analyzed. Finally, prediction formulas for the ultimate load of the columns under eccentric compression were proposed, and a comprehensive comparison of the ultimate loads between the predicted values and experimental values was also conducted. The results indicated that the typical failure characteristics of the eccentrically loaded columns presented lateral deflection together with buckling, while the axially compressed columns displayed expansion and rupture at local positions. Moreover, the ultimate loads of the eccentrically loaded columns decreased by 43.0% and 34.5% in comparison to the columns under axial compression, with the wall thickness factor decreasing from 116.7 to 46.7, respectively. Meanwhile, the ratios of the ultimate loads calculated using design codes to the tested values were in the range of 0.70~0.90, which demonstrated that the design codes could predict the ultimate loads conservatively. Additionally, the ratios of the ultimate loads calculated using the proposed formulas to the tested values were within the range of 0.99~1.08, implying that the proposed formulas were more accurate than the design codes. At the same time, the initial stiffness of the columns under eccentric compression was correspondingly lower than that of the columns undergoing axial compression. The lateral deflections along the height of the columns were almost symmetrical at different loading levels. This study could provide a meaningful approach for designing columns and facilitate their application in civil industry.

Plastic hinge is one of the basic element when designing a bus frame from the view point of passive safety. The paper gives a definition for plastic hinge formed on thin-walled rectangular steel tubes and shows the different types of these hinges. The main characteristics and most important parameters are shown and some test results are given for different kind of plasting hinges, which can be used when designing a bus body for a rollover or front impact accidents.

Instability of a thin-walled stainless steel tube with a crack-shaped defect under combined loading is studied in this paper. Furthermore, the effects of the tube length, crack orientation, and crack length on the buckling behavior of tubes are investigated. The behavior of tubes subjected to combined is analyzed by using the finite element method (by Abaqus software). For cracked tubes with a fixed thickness, the buckling load decreases as the tube length and the ratio of the tube length to its diameter increase. Moreover, the buckling load of cracked tubes under combined loading also decreases with increasing crack length.

Finite element modelling of concrete-filled steel stub columns under axial compression

Seismic behavior of carbon fiber reinforced polymer confined concrete filled thin-walled steel tube column-foundation connection

Modeling of cyclically loaded square thin-walled CSFT columns stiffened by diagonal ribs using OpenSees

Experimental investigation on fire resistance of stainless steel columns with square hollow section

The strength of shaft joints between carbon fiber reinforced plastics (CFRP)and stainless steel bonded with epoxy resin was analytically and experimentally investigated at room temperature and low temperature (-70°C). The distributions of stress for tensile load and thermal stress for cooling in the joint were analyzed by applying the elastic finite-element method. The strength of the joints was predicted by applying the strength laws of CFRP, stainless steel, adhesive layer and their interfaces to the calculated stress distributions. The predicted strength was compared with the experimental strength of the joints. The effects of the overlapped length and diameter ratio between the adherends on the joint strength were examined at both conditions of room and low temperatures. The joint strength for the initial failure is saturated by a certain overlapped length, but the strength decreases with increasing diameter ratio. The final joint strength at low temperature is larger than that at room temperature.

Microstructural characterization and mechanical behaviour of laser powder Bed Fusion stainless steel 316L