الفهرس 
Introduction and Literature ReviewOnly 14 pages are availabe for public view
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Abstract
Abstract
The present research studies the behaviour of pipe bends and determines the Integrity assessment of pipe bends for safe and reliable running of both conventional and nuclear power plants. Leak-before-break (LBB) concept is widely adopted to design the primary heat transport piping system of nuclear power plants. The LBB concept aims at the application of fracture mechanics principles to demonstrate fracture of piping components without giving prior indication of leakage. The thesis attempts to provide contributions to a number of behavioural issues of pipe bends that are lacking in literature. It involves determination the load carrying capacity and deformation behaviour of 90-degree pipe bends suffering from thinning and cracks under the simultaneous action of combined internal pressure and bending moments.
ABAQUS non-linear finite element package has been used in the analysis. Solid break elements were adopted in building of FE models. Verification of FE predictions of collapse loads, elastic stress intensity factors was verified against a recently published experimental/numerical work. Good prediction of smooth, thinned and cracked limit loads were obtained, when the assumption of large displacement was adopted. The thesis also presents a rigorous study of the shakedown limit load for 90-degree pipe bends suffering from thinning subjected to steady internal pressure and cyclic in-plane (closing and opening) bending moment. The shakedown boundary was determined by means of a simplified direct non-cyclic technique, developed recently by Abdalla et al. [1] . The results of the current research include studying the internal local wall thinning of pipe bends at extrados and intrados under combined loading. This
xistudy includes also determination of the LBB curves for cracked pipe bends through studying the ductile crack growth of surface cracks in pipe bends. LBB curves show that the intrados surface cracks are more dangerous than the intrados ones whether they are internal and external.