چكيده به لاتين
Given the vast applications of gas turbines in aeronautical and other industries, it is important to identify the factors and mechanisms that cause damage to these engines. One of these damage mechanisms is fatigue, which is considered in two modes of low and high cycle fatigue. Evaluation of fatigue in gas turbines can be done by various experimental and numerical methods and each of these methods has its own limitations. In this thesis, first an introduction on gas turbines, its structural defects and main concepts of damage mechanics is written, and then a fatigue failure model based on continuum damage mechanics is introduced and the equations used in this model are explained. In this section also discusses the process of solving these damage equations. After explaining the research method, using UMAT subroutine in ABAQUS finit element software, Fortran language code is written to solve the damage coupled elastoplastic equations. In the following section, using this code, a low cycle fatigue analysis is done on a Al2014-T3 specimen with U shape notch under tension-compression loadings and the fatigue life for this specimen is calculated under different loading conditions. Next, the fatigue life analysis is done for a low pressure turbine blade under centrifugal loading, using the written subroutine. In the final chapter of this thesis, a brief summary of previous chapters is given and suggestions for further research are provided.
