The effects of NH 3 -plasma and N 2 -plasma treatment on rubbery polypropylene (PP) membrane upon permeation behavior for CO 2 , O 2 , and N 2 were investigated from their permeability measurements. The NH 3 -plasma and N 2 -plasma treatment on PP membranes could increase both the permeability coefficient for CO 2 and the ideal separation factor for CO 2 relative to N 2 . For O 2 transport, both the permeability coefficient for O 2 and the ideal separation factor for O 2 relative to N 2 also increased. NH 3 -plasma and N 2 -plasma treatment on PP membranes possibly brings about an augmentation of permeability for CO 2 and permselectivity of CO 2 relative to N 2 simultaneously, but unfortunately the plasma-treated PP membrane does not reach the level of CO 2 separation membrane.
The authors proposed an NDE method of detecting the crack developed in the turbine blade by means of digital holographic microscopy (DHM). UT procedures sometimes have limitations in particular cases of in-service-inspections such as the detection and sizing of a creep crack developed in the air-cooled casting blade of the combined cycle gas turbine. The local displacement at the blade surface near the crack during a mechanical loading is different from that of a non-cracked blade. This small different can be detected by DHM. The authors discussed whether this difference affected by the mechanical load between the cracked blade and the non-cracked is detectable by means of DHM or not. In this paper, the authors verified the practical validity of the proposed NDE method using the finite element analyses.
Abstract:A practical evaluation of crack growth lifetime using nonlinear fracture mechanics is needed for remaininglife assessment of high-temperature structural components after long-term service. In this study, creep-fatigue crack growth behavior under displacement-controlled conditions was examined using CT specimens on 2 1/4Cr-lMo steel. The J-integral estimation method and the crack growth prediction method using the fully plastic solution were also examined.Creep-fatigue crack growth under displacement hold could be separated into fatigue crack growth in the cyclic portion and creep crack growth in the holding portion. These two mechanisms were competitive with each other, and crack growth behavior was determined by the dominant mechanism of fatigue and creep. The f -integral approach using the fully plastic solution was introduced for predicting low cycle fatigue crack growth and creepfatigue crack growth with relaxation.The suitability of this solution was verified by comparing prediction with experimental data obtained via the slope-line-control method.
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