FY11 Facility Assessment Study for Aeronautics Test Program

This paper presents the approach and results for the Aeronautics Test Program (ATP) FY11 Facility Assessment Project. ATP commissioned assessments in FY07 and FY11 to aid in the understanding of the current condition and reliability of its facilities and their ability to meet current and future (five year horizon) test requirements. The principle output of the assessment was a database of facility unique, prioritized investments projects with budgetary cost estimates. This database was also used to identify trends for the condition of facility systems

A crack with partially loaded faces between two piezoelectric materials

Розглянуто тріщину між двома п’єзоелектричними півплощинами, береги якої завантажені нормальними та дотичними напруженнями, що забезпечують розкриття тріщини. Вважається, що ці напруження рівномірно розподілені по відрізках, що примикають до вершин тріщини. Використовуючи представлення шуканих факторів через комплексні потенціали, проблема зведена до задачі лінійного спряження, розв’язок якої представлений у вигляді інтегралів типу Коші. Основна увага приділена знаходженню нормального та дотичного стрибків переміщень. Отримано замкнені представлення цих факторів через гіпергеометричні функції. Крім того, використовуючи малість біматеріального параметра, отримано наближені асимптотичні формули. На конкретних прикладах шляхом порівняння результатів розрахунків показано, що вказані наближені формули для стрибків переміщень мають високу точність як для п’єзоелектричних, так і для ізотропних матеріалів.A crack between two piezoelectric half-plane loaded by normal and shear stresses is considered. It is assumed that the stresses are uniformly distributed over the segments adjacent to the crack tips. Using the representation of the unknown factors through the complex potentials, the problem is reduced to the problem of linear relationship with respect to the function analytic in the whole plane except the crack region. The solution of this problem is presented in the form of Cauchy type integrals and the stresses and the derivatives of the displacement jumps are presented in the form of such integrals. Further, the main attention is paid to the determination of the normal and tangent jumps of displacements over the crack region. Applying the Sokhotski–Plemelj theorem and performing the integration the closed presentation of these factors through the hypergeometric functions are obtained. These formulas are complicated and in many cases they are inconvenient for numerical analysis. However the obtained solution depends on the bimaterial parameter, which is very small for most of piezoelectric material combinations. Therefore in addition, the approximate asymptotic formula is obtained using the smallness of the mentioned parameter. Similar analysis has been performed for a crack between two isotropic materials as well and exact and approximate formulas for the normal and shear displacement jumps and their derivatives are presented in this case as well. The numerical analysis has been performed for the typical piezoelectric materials PZT-4 and PZT-5 and the normal and shear crack openings calculated by exact and approximate formulas are presented graphically. Similar figures for a crack in the isotropic bimaterial are presented as well. In all considered cases the comparing of the calculation results show that the approximate formulas for jumps of displacements have high accuracy for both piezoelectric and for isotropic materials. It means that that these approximate formulas can be used for the analysis of interface cracks with pre-fracture zones

Математика

The educational text-book contains theoretical material and problems according to mathematical chapters “Algebra and Analyses”, included in the program for pre-university training of international students. The tasks for independent studying are illustrated in the examples. Designed for students and teachers of all kinds of pre-university training

The Method of Manufacturing Nonmetallic Test-Blocks on Different Sensitivity Classes

Nowadays in our modern world there is a vital question of quality control of details made from nonmetallic materials due to their wide spreading. Nondestructive penetrant testing is effective, and in some cases it is the only possible method of accidents prevention at high-risk sites. A brief review of check sample necessary for quality evaluation of penetrant materials is considered. There was offered a way of making agents for quality of penetrant materials testing according to different liquid penetrant testing sensibility classes