In this paper, the first and second stage compressor blades of a gas turbine were studied by the experimental and numerical modal analyses. At first, the geometric models of these blades were generated by the 3D scanner and then the mode shapes and the natural frequencies of each blade were extracted by a series of numerical modal analyses. The numerical results were compared with the data obtained from the experimental modal analysis and the validity and accuracy of the developed numerical models were confirmed. Unlike most studies that use fixed-free boundary condition for performing a modal analysis, this objective was pursued by applying a free-free boundary condition. This study also investigated the effect of using wax or glue for mounting the accelerometer on the blade by assessing the FRF curves obtained from the modal tests in the frequency range of 0-10000 Hz. The sensitivity of the test results to applying free-free boundary condition, the number of accelerometers and their positions were investigated by defining three modal test configurations. The results obtained by these test configurations were compared with the results of numerical analyses and finally, the best configuration for the modal test of the studied compressor blade was determined.

Composite materials show different mechanical properties in different directions which leads to complications in the prediction of their behavior. In addition to being inhomogeneous, behavior of composite materials is highly dependent on the curing process and many studies have tried to address these issues. Residual stress can induce high errors in prediction of composite material properties and leads to a difference between theoretical and experimental results. It has been observed that the humidity of environment and the chemical properties of composite materials are also important. Fewer studies have addressed thick layer composites and no damage theory has been developed for these materials. In this paper residual stress in thick layer composites have been studied. Using numerical analysis, the curing process has been modeled and mechanical properties of a thick layer composite are obtained and the induced residual stress in these composites has been assessed. Unlike thin layer composites, the stress in each layer is not specific and a tensile and compressive stress field can exist simultaneously in thick layer composites.

A land-based gas turbine may operate at the different environment including corrosive and dusty environments. These conditions can cause early damages in the “cold” parts as well as in the “hot” parts of the gas turbine. In this research, fatigue life of a compressor blade is predicted with and without damages. Damage is considered as a notch at the blade and is classified as three types of short, medium and long notches. These are numerically simulated in the compressor blade and fatigue crack initiation life is calculated. Stress analysis is carried out using finite element analysis followed by fatigue life calculations. Furthermore, the influence of blade tip displacement on life of the undamaged and damaged blade is investigated. Moreover, the effect of damage & apos; s size and location on blade’s life is reported. This procedure can be tuned with corrosion damages observed during the minor inspection where the gas turbines are operating in the unusual environments.