On the Concept and Mechanism of the (MN - r_p - σ_θ) Fracture Theory

摘要

The current theory of "Circumferential Strain Energy (MN- r_p - (σ_θ)" is new fracture theory recently developed. This theory depends on the calculation of the components of critical strain energy density factors at the position of maximum circumferential tensile stress (σ_θ)_(max) regarding the minimum critical radius (r_(pc))_(min) of the plastic zone at the crack vicinity. This theory can solve the problems of cracks under any load condition with a higher accuracy than other theories. It can be applied in linear elastic fracture mechanics LEFM for brittle and quasi-brittle homogeneous materials and composites. It can be extended to elastic plastic fracture mechanics EPFM. It can be extended and can be applied to ductile materials. This theory, by using its fracture mechanism and hypotheses can investigate each of the cracking load and crack propagation directions. It can predict also the fracture toughness, crack growth path and the crack history. Itcan be used for estimating the safe life time of any structure. It is developed for mixed modecracks for isotropic brittle materials and can be applied for group of cracks under static, cyclic anddynamic loading. Also, it can be applied for cracks under thermal stresses.