Control Of Ductile Fracture Research Articles

Analysis of an existing hydrocarbon gas pipeline for conversion to dense phase CO2 service

Esso Australia is investigating the feasibility of a carbon capture and storage (CCS) project in East Gippsland, Victoria. Known as the South-East Australia Carbon Capture and Storage (SEA CCS) Hub, the project aims to re-purpose existing infrastructure and offshore depleted hydrocarbon reservoirs to store carbon dioxide (CO2). The project aims to reduce greenhouse gas emissions from Esso’s Longford Gas Conditioning Plant, and to unlock future CCS opportunities for Australia. One option identified as part of the SEA CCS feasibility was to convert part of the existing onshore section of the Barracouta 450 mm gas pipeline to Longford Gas Plant (BTA450-LFD), Licence PL/1 under the Victorian Pipeline Act, to dense phase CO2 service. This paper documents the initial findings of the potential for the onshore section of the BTA450 for conversion, with particular emphasis on brittle and ductile fracture control considerations. In summary, when attempting to convert existing hydrocarbon gas pipelines for CO2 service, operators need to undertake an appropriate assessment of fracture control considerations. The insights of this paper may serve as a useful guide document for assessing other existing onshore pipelines for CO2 service conversion. Due to the thermal modulation effect of the surrounding water for subsea pipelines, this guidance does not apply to subsea pipeline sections.

Formability enhancement in hot spinning of titanium alloy thin-walled tube via prediction and control of ductile fracture

The damage and fracture in hot spinning of titanium alloy is a very complex process under the combined effects of microstructure evolution and stress state. In this study, their dependences on processing parameters were investigated by an integrated FE model considering microstructure and damage evolution, and revealing the effects of microstructure and stress states on damage evolution. The results show that the inner surface of workpiece with the largest voids volume fraction is the place with the greatest potential of fracture. This is mainly attributed to the superposition effects of positive stress triaxiality and the smallest dynamic recrystallization (DRX) fraction and β phase fraction at the inner surface. The damage degree is decreased gradually with the increase of initial spinning temperature and roller fillet radius. Meanwhile, it is first decreased and then increased with the increases of spinning pass and roller feed rate, which can be explained based on the variations of β phase fraction, DRX fraction, stress state and tensile plastic strain with processing parameters. In addition, the dominant influencing mechanisms were identified and discussed. Finally, the thickness reduction without defect in the hot spinning of TA15 alloy tube is greatly increased by proposing an optimal processing scheme.

G0300-1-3 ポリカーボネート板の延性 : 脆性破壊遷移現象について([G0300-1]材料力学部門一般講演(1):破壊)

Ductile-brittle fracture transition of notched polycarbonate plate was studied with respect to the specimen thickness t, notch root radius ρ and the ratio of K_II to K_I As a result, there was a tendency to arise the brittle fracture as increased with t and 1/ρ under mode I loading. However, failure mode of natural cracked specimen, ρ = 0, of thick plate was ductile fracture. Moreover, it was revealed that failure mode was put under the control of ductile fracture as increased with the ratio of μ = K_II/K_I under mixed-mode loading. Caustic pattern formed by the information at the crack tip was obtained, and the ratio of μ was evaluated from the configuration of this pattern.