Fracture Analysis of Ductile Materials by Mean of Recent Fracture Theory (MN - r_p - σ_θ)

摘要

The current theory is based on the original version of (MN -r_p σ_θ) theory for brittle and quasi-brittle materials. It was developed with Linear Elastic Fracture Mechanics LEFM to study the cracking in the elastic stage for non ductile materials and materials with low ductility. In this research a new of the theory version for the fracture of pure ductile materials and fracture in brittle - ductile transition for semi brittle semi ductile materials is proposed. This new proposed theory for ductile fracture is called the DMN-ductile theory. It has a new concept and a new mechanism. It proposed that the fracture direction can be predicted in the elastic stage in LEFM where the critical fracture load will include two parts one from the elastic stage and the other part from the plastic stage. The fracture load would be determined with Elastic - Plastic Fracture Mechanics EPFM. The direction of the fracture will be in LEFM in the beginning of the propagation and will extend in the same direction in the plastic stage for the same fracture increment, but it may change in the nest fracture problems. In addition, it unifies all views of researches on ductile fracture energy approach. It could introduce a new concept for the ductile fracture process for dealing with any crack and for predicting any required fracture aspect.