Analysis of cracked plates subjected to out-of-plane loadings
Abstract
Stress singularity near a crack tip is one of the most important parameters in structural design. Fracture parameters such as stress intensity factors or strain energy release rates are often required in design considerations. This research aims to find those fracture parameters for through-the-thickness cracks in plates subjected to out-of-plane loadings. For the thin plate assumption, classical plate theory and Reissner's plate theory are employed to solve the problems. Modified crack closure method in combination with finite element method is also investigated. The research can be divided into four major topics: (1) Although the stress intensity factor and near-tip stress distributions given by the Reissner's plate theory are different from classical plate solutions, the total strain energy release rate based on Reissner's plate theory is shown to approach the classical plate solutions as the ratio of plate thickness to crack size approaches zero. (2) For plate subjected to uniform bending moment, the stress-free conditions along the crack face lead to interpenetration of the crack faces. A constraint model using plate theories in combination with plane elasticity assumption is investigated. The constraint conditions relate crack rotation and in-plane displacement along the crack faces to satisfy the compatibility condition at compressive edges. The influence of the closure on the stress intensity factors is evaluated. (3) For plate subjected to transverse shear forces, the problem is solved using classical plate theory and Reissner's plate theory. The stress intensity factors are obtained and the strain energy release rates associated with mode II and mode III are evaluated. Two plate solutions are compared. (4) The modified crack closure method in combination with the finite element method is investigated for different loading conditions. The accuracy of the method is evaluated. The results based on classical plate element and Mindlin's plate element are also compared.
Degree
Ph.D.
Advisors
Sun, Purdue University.
Subject Area
Aerospace materials|Mechanical engineering
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