Papers by Author: Roderick A. Smith

Abstract: Full-scale burst test data of high-grade line pipes for high-pressure gas pipelines were referred to, and 3-D elastic-plastic finite element analysis was carried out using the test data for the calculation of fracture parameters. Ductile crack initiation was evaluated by the intersection of a toughness locus and a crack driving force curve, where the toughness locus was indicated by the relationship between the critical equivalent plastic strain and the stress triaxiality, and the crack driving force curve was shown by a history of the equivalent plastic strain and the stress triaxiality at characteristic distance. In addition, ductile crack rapid propagation was assessed by the relationship between the critical CTOA and the global constraint factor, where the critical CTOA remained almost constant because of high constraint.

Abstract: Static ductile crack propagation tests were conducted using two pressurised thin carbon-manganese steel tube specimens, and the crack tip opening angle (CTOA) was measured using digital images captured on specimen surface. The critical values of CTOA for static crack propagation decreased with crack extension while propagating crack was short. After the crack grew up to the distance of the tube specimen thickness, the critical CTOA exhibited nearly constant. These tendencies were the same as those of referential data in the thin single edge notched tension (SENT) specimens of the same tubes. Using the data of both tube specimens and SENT specimens, it was noted that the higher crack velocities slightly reduced the constant CTOA. A global constraint factor was calculated for each tube specimen, and the constant CTOA decreased with the increase of the global constraint factor. In addition, a dynamic ductile crack propagation test of a tube specimen was carried out, and a crack velocity was measured. The estimation of the constant CTOA for dynamic crack propagation in the tube specimen was performed by using the crack velocity.

Abstract: Static and dynamic ductile crack propagation tests were carried out using thin single edge notched tension (SENT) specimens of carbon-manganese steel, each of which had a fatigue pre-crack or a sharp V-notch as a crack initiator. The crack tip opening angle (CTOA) was measured using digital images on the surface of the SENT specimens, and the critical values of CTOA for crack propagation decreased with increasing crack length while initial crack growth was still small. After the initial crack growth up to the distance of the specimen thickness, the critical CTOA remained almost constant. These tendencies were common in static and dynamic crack propagation specimens as well as fatigue pre-cracked and sharp V-notched specimens. There was no particular difference in the static crack propagation characteristics of both fatigue pre-cracked and sharp V-notched specimens. On average, it was observed that higher crack speeds affected the constant values of the critical CTOA by slightly reducing them. The constant CTOA tends to decrease with an increasing global constraint factor, and this suggests that the factor is insensitive to a crack starter, fatigue pre-crack or a sharp V-notch, but relatively sensitive to crack speed.

Abstract: This paper emphasises the importance of the knowledge of service loads to both the initial design process and the maintenance of structural integrity during the lifetime of engineering components and structures. Three case studies are presented. All involve accidents which caused major loss of life: the Hillsborough Stadium disaster in Britain, the German ICE train crash at Eschede and the China Airlines disaster off Taiwan.