Seminar
MECHANICS OF MACHINES AND MECHANISMS - MODELS AND MATHEMATICAL METHODS

 

PROGRAM

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Plan rada Seminara Mehanika mašina i mehanizama - modeli i matematičke metode za JANUAR 2019.

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UTORAK, 22.01.2019. u 17:00, Sala 301f, MI SANU, Kneza Mihaila 36
Gordana Kastratović, Faculty of Transport and Traffic Engineering, University of Belgrade, Serbia
NUMERICAL COMPUTATION OF STRESS INTENSITY FACTORS OF SUPPORTING AERO STRUCTURES WITH MULTIPLE SITE DAMAGE
Multiple site damage (MSD) represents the simultaneous development of fatigue cracks at multiple sites in the same structural element. It often occurs in longitudinal and circumferential riveted lap joints in wings and fuselages, and can be very serious, because of possible link up of adjacent cracks creating one large crack that can cause catastrophic failure. The prediction of crack-growth rate, residual strength and fatigue life in the presence of MSD, requires accurate calculation of the Stress Intensity Factors (SIFs) at each crack tip. The problem becomes more difficult when crack propagation has to be treated and therefore successive calculations are required. As technology and computer sciences became more available, numerical computational methods had become an indispensable tool for SIFs determination, but they remain a challenging problem in computational fracture mechanics. This presentation embodies an effort to explore and to demonstrate the capacity, performances and difficulties of SIFs determination by usage of some widely available numerical computational methods. The stress intensity factors for several aero structural configurations with MSD were considered by using three different computational methods: finite element method (FEM) with singularity elements, extended finite element method (X-FEM), and the approximate method based on superposition. This talk represents a review of investigations carried out in cooperation with A. Grbovic, N. Vidanovic and A. Sedmak.

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UTORAK, 29.01.2019. u 17:00, Sala 301f, MI SANU, Kneza Mihaila 36
Stevan Maksimović, Military Technical Institute, Belgrade, Serbia
TOTAL FATIGUE LIFE ESTIMATION OF AIRCRAFT STRUCTURAL COMPONENTS UNDER LOAD SPECTRUM
This work is focused on developing computation procedure for strength analysis of aircraft structures with respects to fracture mechanics and total fatigue life estimation. For that purpose here will be considered computation procedures for total fatigue life estimation of constructions under cyclic loads of constant amplitude and load spectrum. The finite element method (FEM) allowed the prediction of the point of crack initiation and the crack propagation using the orientations of the maximum principal stresses. Stress intensity factor (SIF) is the base parameter in strength analysis regarding fracture mechanics. For correct determination SIF in this work special singular finite elements will be used. An special aspect of this investigation is based on application of Strain Energy Density (SED) method in residual life estimation of structural components with initial cracks. Verification of computation procedures for life estimations will be supported with corresponding experimental tests for determination low cyclic fatigue properties of materials and corresponding parameters of fracture mechanics including fatigue tests of representative aircraft structural components.

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Seminar Mehanika mašina i mehanizama - modeli i matematičke metode započeo je sa radom u junu 2018.god. Seminar se održava do dva puta mesečno, utorkom u periodu od 17.00 - 19.00 u Matematičkom institutu SANU.

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