Research On Deepwater Riser With Crack Numerical Simulation Of Fatigue Fracture

Deepwater oil and gas exploration and production activities increased significantly, is the world's offshore oil and gas general trend of industrial development, China National Offshore Oil Corporation has been an open tender to the world's deep water depth of 600～2000m. With increasing water depth, deep development of technology and equipment continue to face new challenges for deepwater production systems, standpipe system as the connecting surface of the water floating and subsea quipment installation tube, the role is critical. Load of deepwater risers, as waves, wind and field operations, such as dynamic load factors are very complex, the failure of welded structure design control and reliability are important factors to consider.This opposition exists pipe girth weld defects in case of fracture morphology and fatigue life of the finite element analysis of welded opposition group before the deviation caused by the stress concentration and fatigue life were studied and theoretical validation, specifically as follows:(1) With the existence of the riser girth weld defects cases, different stress amplitude, defects in different locations on the crack morphology and fatigue life. The finite element analysis showed that the crack shape and Brazil COPPE/UFRJ the experimental results.(2)Riser of the group before welding and stress concentration caused by deviation of fatigue life. The results show that a large group of error makes the stress is too concentrated, the impact on the fatigue life can not be ignored. Opposition control system main components, the main connection riser connector was introduced. Relevant to the content of this paper, the international status of girth welds fatigue life are described. On the marine riser J-SCR pipe laying process was described in detail.(3)Riser on the existing international standard girth fatigue problems were analyzed. Pointed out that the BS7910 standard is too conservative, and were verified by simulation.(4)Introduced the now commonly used in fatigue fracture software. Given FRANC3D software tutorials too few cases, more detailed explanation of the operation of the software to use.(5)In this paper, finite element analysis of defects lead to fatigue, riser group bias caused by the stress concentration was studied for welded joints of the marine riser in the future, the application of oil and other fields to lay a theoretical foundation.