The primary task of this study is to offer reliable and accurate model of a bladed disk containing cracked blade. This model allows simulation of bladed disk dynamic behavior for various crack positions and lengths. Due to absence of cyclic symmetry caused by crack presence in the disk, a reduction procedure was implemented to simulate full bladed disk. It is proposed to use crack location as an interface between two substructures for subsequent fixed-interface method application. Harmonic balance method was applied to take into account crack nonlinear behavior under periodically varying loads. The method implementation considers contact interaction between crack sides at the crack being closed. The contact force is calculated using penalty method of contact force calculation. Relative vertical displacements between nodes in contact were used as nonlinear degrees of freedom (DOFs). Developed bladed disk model is able to take into account external excitation forces phase lag caused by difference between number of rotor and stator blades. Also presence of mistuning was considered. It was shown that certain level of mistuning can directly affect cracked blade detectability. Cracked blade dynamic behavior localization plays here very important role. Absence of cracked blade localization results in impossibility to separate cracked blade response at any mistuning level. Validity of zig-zag diagram for structures with disrupted symmetry is shown using developed bladed disk model with presence of certain level of mistuning.
The study intends to simulate the process of the blade tip amplitude calculation by the tip-timing method. An attention is focused on tip-timing measurements for detection of a cracked blade from the bladed disk forced response. The cracked blade is considered within frameworks of the bladed disk dynamic model that takes into account mistuning presence. Nonlinear formulation of a crack behavior is done with the harmonic balance method in its combination with the contact analysis that allows simulation of crack breathing. In order to make the cracked blade detection process evident, the crack length and location are set in such a way as to produce the cracked blade frequency localization. Reconstruction of the blade tip amplitudes is attained with the arriving time of measured probes of the blade tips. The results are compared with the blade forced response obtained by the bladed disk dynamic model. A possibility is also considered how to reconstruct time-history of the bladed disk forced response with tip-timing data.
A cracked blade non-linear dynamic analysis was performed, taking into account contact interaction between crack sides. The contact-induced non-linear problem was solved by using the harmonic balance method. Accuracy and computational efficiency are demonstrated by comparing the results with the time integration of the system's motion equation Problem size reduction was performed using system fixed-interface method. They suppose that a crack forms an interface between two sub-structures and use a relative degree of freedom to describe the motion of crack sides. The influence of centrifugal forces was investigated in order to understand the necessity of problem non-linear formulation depending on crack location and frequency of rotation.
The mathematical models of damageability under static and cyclic loadings are investigated. The parameters of damageability and endurance are considered necessary for the calculation of long-term durability wear and low-cycle and high-cycle fatigue, thermo-cyclic endurance and deformation as well as general models, taking into account multi-axis and multicomponent loads. The models of damageability at loading range, the probabilistic models of endurance and accumulation of damage at random influence are given. Probabilistic criteria for service life estimation and their connection with accumulated damageability are researched.
Розглянуто технологічний процес забезпечення запасними частинами, інструментами, приладами і матеріалами системи технічного обслуговування і ремонту парку повітряних суден (ПС) авіакомпанії на основі розрахункового методу з метою визначення кількісного складу комплекту запасних частин на заданий період експлуатації при обмеженій сумі фінансування.Ключові слова: система технічного обслуговування і ремонту, льотна придатність, матеріально-технічне забезпечення, авіаційно-технічне майно, ймовірність безвідмовної роботи, резервні елементи.In the article were considered the questions of technological process of providing the Aircraft Maintenance System by spare parts, instruments, equipment and materials on the base of calculation method with the goal to determine the quantity of spare parts on the defined operating period with limited funding.
Розглянуто ресурсні можливості жароміцних матеріалів роторних деталей «гарячої частини» авіаційних газотурбінних двигунів (ГТД) і енергетичних установок (ГТУ) в прискорених термоциклічних випробуваннях. Показано можливість застосування розрахункового методу на основі емпіричної математичної моделі граничних термомеханічних напружень екстремальних рівнів, що діють у критичних точках деталей «гарячої частини» ГТД. При цьому припускається, що зразки матеріалів працюють на термоциклічних режимах, максимально наближених до умов роботи роторних деталей в критичних точках, що лімітують термін служби і призначений ресурс авіаційних ГТД та енергетичних ГТУ.Ключові слова: емпірична модуль, граничні статичні і термічні (термомеханічні) напруження, термомеханічні прискорені випробування, жароміцні матеріали, «гаряча точка» ГТД. The considered resource possibilities of heatproof materials of rotor details of "hot part" of aviation turboengines (GTE) and power plants (PP) are in speed-up thermal-cycle tests. The shown possibility of applicationof calculation method is on the basis of empiric mathematical model of maximum thermo-mechanical tensions of extreme levels which operate in the critical points of details of "hot part" of GTE. It is thus assumed that the standards of materials work on the thermal-cycle modes of maximally close to the terms of work of rotor details in critical points which limit tenure of employment and appointed resource of aviation GTE and PP.
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