STRUCTURAL INTEGRITY OF DUCTILE MECHANICAL COMPONENTS SUBJECTED TO CREEP: DAMAGE AND FRACTURE MODELLING

This research is aimed at the computational assessment of the structural integrity in ductile mechanical components, subjected to creep based on damage and fracture analysis. In the present work, the implementation of constitutive damage model concerning the void damage and crack evolution in the material is performed. It leads to the development of a new
model called Rousselier-UMAT-XFEM (RuX) model. To the author’s knowledge, this is the first attempt where the XFEM is formulated with the Rousselier model in ductile fracture
analysis for micromechanical damage problems. The potential of the RuX model is tested in two-dimensional and three-dimensional problems, and the results are in good comparisons with the literature. The study is continued to investigate the creep failure behaviour of ductile
material by simulating the predictive modelling of creep crack initiation and growth, and the results are being verified accordingly. Next, the development of the constitutive creep damage model is carried out where a new model called as Modified-Robinson-Rousselier
(MRR) model is proposed. The MRR model is tested in tensile creep tests and showed good estimation results with the experimental data in terms of the void damage growth and
creep strain curve. Furthermore, the extended analysis of MRR model is identified in which the XFEM technique is implemented to introduce the crack development in the analysis. As a result, a new model called as MRRX model is suggested to predict the creep damage behaviour due to void-crack growth mechanism. The results are compared with the literature and showed a worth comparison regarding the evolutions of crack growth and void formation. Therefore, this work is successfully implemented to enhance the predictive modelling tools for the application of fracture damage mechanics and computational approach in the structural engineering problems.