Corrosion Effects on the Ductile Fracture, Strength and Reliability of Membranes, Plates and Shells.

Corrosion;Ductile Fracture;Membrane;Pipeline Bending Capacity;Reliability;Naval Architecture and Marine Engineering;Engineering;Naval Architecture & Marine Engineering

Yu, WeiweiVargas, Pedro M. ;

University of Michigan

关键词: Corrosion;    Ductile Fracture;    Membrane;    Pipeline Bending Capacity;    Reliability;    Naval Architecture and Marine Engineering;    Engineering;    Naval Architecture & Marine Engineering;   

Others  :  https://deepblue.lib.umich.edu/bitstream/handle/2027.42/63746/wwyu_1.pdf?sequence=1&isAllowed=y

瑞士|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

Corrosion is a degradation of material properties and strength due to interactionswith the environment. This dissertation details the analyses of corrosion effectson two failure modes: ductile fracture and bending strength of membranes, platesand shells. Furthermore, corrosion induced stress or strain concentration effects areincorporated in reliability studies.Annular elastic membrane deformation is studied analytically. Large out-of-planeship hull deformation in ship grounding or collision is often analyzed by using membranetheory. It has been found that older ships with corrosion are more susceptibleto fracture in grounding or collision. Therefore, corrosion effects on ductile fractureinitiation are studied next. Corrosion effects inducing strain localization are revealedby a 3D model based on the finite element method. The relationship between localand overall strain and model size effects are examined for a rectangular plate underuniaxial and biaxial tension. The ductile fracture of corroded plates is also studiedunder different pit intensities, distributions and loading conditions.Corrosion also degrades the bending capacity of pipelines. Previous research focusedmainly on burst capacity of corroded pipelines. Key points of finite elementanalyses of corroded pipelines in bending are addressed in detail. An experimentaltesting program is fully reported and validates the finite element analysis results.Bending strength reduction because of corrosion has been revealed. Secondary effectsin the experimental testing are also discussed.Finally, corrosion induced high local stress and strain levels are evaluated bymeans of stress and strain concentrations. Both analytical and numerical analyses areperformed including the use of Neuber’s stress concentration theory. Such studies arefurther incorporated into the reliability analyses of corroded plates. Structural failureprobability and partial safety factors are calculated by considering the randomness ofcorrosion geometry and of the applied nominal strain. A reliability study is appliedon a corroded bottom shell of a double bottom oil tanker in ship grounding.