The stress redistribution locus (SRL) method has been proposed to provide a reasonable estimate for inelastic behavior employing elastic, elastic-plastic and⁄or elastic-creep FEM analyses. A theoretical and numerical analyses were carried out for a double and a single thick cylinder subjected to thermal transients, and the characteristics of SRL was investigated. When the stepwise temperature is raised inside an inner cylinder of the double thick cylinder model, the normalized equivalent stress-strains almost depict on the proposed SRL curve provided the ratio of the inelastic area to the inner cylinder remains below 30%. However when the temperature variation between both cylinders becomes to be greater, the normalized equivalent stress-strain curve leaves away from the proposed SRL curve. After analyses for the double thick cylinder model, inelastic behavior for the single thick cylinder model under a linear or a quadratic distribution of temperature was evaluated using elastic, elastic-plastic and elastic creep FEM analyses. Most normalized equivalent stress-strain loci draw nearly the same curve, and they are independent of temperature variations ΔT. Furthermore the SRL behavior is a bit depending on the configuration of temperature variation inside the cylinder but there is little influence on material properties and dimensions of cylinder. Thus it is verified that the present SRL procedure could estimate inelastic behaviors, and that its criterion guarantees the robust structural design for complicated components.

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The effects of overload on the threshold stress intensity factor for stress corrosion crack (K_ISCC) of stainless steel were studied. Tensile overload was applied to a wedge opening loaded (WOL) specimen of SUS316. Then, SCC tests were carried out to determine the resultant K_ISCC. As a result, the appareut value of K_ISCC increases as increasing a stress intensity factor by tensile overload (K_OV) . The effects of tensile overload on K_ISCC and the threshold stress intensity factor range for fatigue (ΔK_th) were compared. It was found that the effects of tensile overload on K_ISCC were larger than that on ΔK_th.

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The stress rupture and tensile strength of unidirectional CFRP (T700SC⁄Epoxy) have been investigated experimentally. The stress rupture data revealed that (1) the difference of the maximum rupture time and the minimum rupture time in the same test load condition is more than 40, 000 hours, (2) the relationship of the test load condition and rupture time is unclear, and (3) origin of failure as stress corrosion does not exist on the surface of carbon fiber after the test. These results imply that CFRP is less susceptible to stress rupture. The tensile strength data revealed that the tensile strength in CFRP can be obtained on the basis use of the weakest link model. The method of calculation of the expectation burst pressure of the CFRP composite vessel in consideration of the length dependency of CFRP has been proposed.

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Two tank explosions simultaneously occurred at a salt water disposal facility in Lamesa, Texas on May 15, 2009. One tank launched as a skyrocket, and the roof plate separated and flew in the other tank at the explosion. The frangible roof joint is designed so that the strength of the sidewall-to-roof joint is weaker than that of the sidewall-to-bottom joint under overpressurization in aboveground oil storage tanks. This rule did not perform as intended in the tank which launched. This paper presents a consideration on the frangible roof joint design due to the tank explosion.

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