The Finite Elements With Generalized Degrees Of Freedom Developed For Fracture Analysis Of Structures

This dissertation establishes the finite elements with generalized degrees of freedom in fracture mechanics on the basis of finite elements theory and linear elastic fracture mechanics theory. It also gives relevant numerical tests to demonstrate the accuracy and efficiency of this method.The main contributions of the thesis are as follows:1. Based on isoparametric element theory and Fortran 90, the finite elements program for normal plane problem is composed;2. Based on the isoparametric singular element theory a quarter singular element is developed, the finite elements program for fracture analysis of structures is put forward using Fortran 90. Examples show that this element is accurate, and reflects the singular property of the stress field around the crack tip.3. The finite elements with generalized degrees of freedom developed for fracture analysis of structures. The singular strip element and transition element are constructed based on the theory of globed field assorting with local field. A large quantity ofnumerical calculating is undertaken. The results of them are compared with those resulted from isoparametric singular element theory, thus the advantage of the finite elements with generalized degrees of freedom is demenstrated in fracture analysis of structures.