In this study, the effect of blade sequences is investigated through the response of mistuned blades. A particular engine order excitation is assumed and a genetic algorithm is developed to obtain the optimal blade sequence. The genetic algorithm provides excellent results, and the mistuning effects are reduced significantly by the optimal arrangement of mistuned blades.

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In this study, the assembling conditions of blades and rotors are investigated by the FEM model of a blade with the different boundary conditions. It is assumed that the modal properties of blades are identical and the blade modal frequencies are changed by the assembling condition only. It is shown that the change in modal frequency by the assembling condition is approximately 0.25 % in normal operating conditions. However, the variance of blade response can be increased by more than 30 % under narrow-band random excitations.

In this study, the effects of large geometric mistuning on blade response are investigated considering the change of mistuning properties and excitation characteristics. The response variations because of large mistuning are negligible under white noise excitations and are highly significant under narrow band excitations. For the different excitation correlations, the responses are represented using non-dimensional variables in order for the results to be comparable to each other. It is shown that the ratio of the modal frequency between the tuned and large mistuned blades determines the propagation direction of the natural frequencies of the mistuned system, therefore, the responses of large mistuned blades depend primarily on their level of modal frequency.

In this study, the performance of friction dampers of a geometric mistuned bladed disk assembly is examined under random excitations. The results are represented by non-dimensional variables. It is shown that the performance of the blade-to-blade damper can deteriorate when the correlated narrow band excitations have a dominant frequency near the 1st natural frequency of the bladed disk assembly. Based on a simple model of a geometric mistuned bladed disk assembly, the analytical technique shows an efficient way to design friction dampers.

In this study, the effects of excitation correlation on the mistuned bladed disk assembly are investigated. Base correlation patterns are used to generate a general correlated excitation. An example of a mistuned system is investigated to examine the interaction between excitation correlations and resembled natural modes. It is shown that the blade responses are very sensitive to the correlation of excitations.

Using non-dimensional variables, the performances of friction dampers of a mistuned bladed disk assembly are examined for different types of excitation: white noise excitation, independent narrow band random excitation and sinusoidal excitation with unknown amplitudes. Based on the harmonic balance method, an analytical technique is developed to compute the statistics of response for sinusoidal excitation with unknown amplitudes. The performances of blade-to-blade and blade-to-ground dampers are compared under different types of excitation. It is found that non-dimensional optimal normal loads of friction dampers are almost independent of the nature of excitation. Therefore, optimal normal loads of friction dampers can be chosen without any knowledge of the nature of excitation.