Aerodynamic-structural optimization of aircraft lifting surfaces

Istraživanjem tokom izrade ove disertacije sprovedena je multidisciplinarna studija kojom je izvršeno numeričko modeliranje interakcije fluid-struktura uzgonskih poršina letelica. Numeričko modeliranje fenomena interakcije na relaciji fluid-struktura sprovedeno je posrednim sprezanjem aerodinamičkih i strukturalnih proračuna, a sa visokim stepenom pouzdanosti numeričkog predviđanja. Primenom predloženog algoritma postignuta je veća tačnost aerodinamičko-strukturalnih analiza u odnosu na postojeće postavke, dok je sama pouzdanost numeričkih proračuna utvrđena u odnosu na sprovedene aerodinamičke i strukturalne eksperimente. U okviru definisanih karakterističnih (kritičnih) režima tokom procesa eksploatacije, izvršen je izbor optimalnog aerodinamičkog oblika koji ispunjava taktičko-tehničke zahteve projektovanja, kao i propisana ograničenja, a na osnovu čega su aerodinamičko-strukturalne karakteristike letelice unapređene. Postupak optimizacije je baziran na korišćenju aproksimativnog modela, koji je opisan statističkim metodima, dok je sam optimajzer evolucionog tipa. Predloženo modularno okruženje predstavlja osnovni metod multidisciplinarne optimizacije opslužen od strane jedinstvenog optimajzera. U okviru kreiranog monolitičkog okruženja sprovedena je optimizacija krila balističkog projektila kratkog dometa. Metodom meta-modeliranja prostora pretrage značajno je povećan broj mogućih optimalnih geometrija koje zadovoljavaju i ciljeve i ogreničenja. Osnovni doprinos predstavlja aerodinamičko-strukturalno unapređivanje inicijalne geometrije analiziranog, realnog balističkog projektila. Optimizacijom su postojeće karakteristike i performanse projektila podignute na viši nivo, čime je u okviru realnih režima eksploatacije ostvareno povećanje finese, a time i dometa projektila, dok je sa aspekta sigurnosti pouzdanost samog projektila poboljšana. Ceo postupak je doprineo da troškovi razvojnog programa budu značajno umanjeni, a što se posebno ogleda u uštedama na polju eksperimentalnih i numeričkih resursa. Ostvarenim rezultatima analizirane letelice postignuti su realni uslovi za potencijalni razvoj jednog takvog raketnog sistema, a sam razvojni program je u mnogome unapređen i može poslužiti za razvoj i drugih letelica. Kreiranje numeričkog okruženja koje omogućava ovakav vid analize predstavlja značajan naučni i praktični doprinos pri spregnutom modeliranju ponašanja strukture izložene dejstvu fluida.In this research a multidisciplinary study of numerical modeling of fluidstructure interaction phenomenon was carried out. Numerical modeling of fluidstructure interaction of lifting surfaces was accomplished thru closely coupled aerodynamic and structural computational domains, with high computational reliability and accuracy which were established regarding conducted aerodynamic and structural experiments. The proposed algorithm gives better numerical accuracy of aerodynamicstructural analysis compared to existing similar methods. Multipoint and multidiscipline aerodynamic shape optimization, with respect to predefined objectives and constrains, was carried out in order to achieve the improvement of initial aerodynamic-structural performances of aircraft. The multidisciplinary feasible method proposed in this thesis, is a single level method driven by meta-modeling based evolutionary optimizer. The proposed monolithic environment was used for optimization of a realistic short range ballistic missile fin. This kind of analysis enabled increased number of feasible optimal geometries of fin, while its special feature was the overall improvement of ballistic missile initial geometry. Within realistic multipoint regimes, the initial performances of missile were optimized and upgraded, especially the missile fitness, and therefore range. At the same time, the reliability of missile overall behavior was improved. The whole procedure significantly decreased the costs of developing program, especially in use of experimental and numerical resources. The achieved results, regarding the ballistic missile, provide real conditions for potential development of such and similar aircrafts, with upgraded developing program. The established multimodular design optimization environment which enabled this kind of analysis presents significant scientific and practical contribution of fluid-structure interaction numerical modeling

Simulacija širenja prsline u titanijumskim mini dentalnim implantima (MDI)

Developments in mini dental implants (MDI) manufacturing are aimed at making them more biocompatible and, at the same time, lighter, more durable and simultaneously safer than the existing implants. But, occasionally, during installation the failure of MDI may occur or cracks may appear, which could lead to the later failure of MDI. In order to understand and assess crack growth in titanium MDI, Finite Element (FE) software packages ANSYS v13 and FRANC3D v5 have been used. Using FRANC3D software different crack sizes and shapes have been modeled and simulations of crack propagations in three-dimensional model of MDI have been performed. Based on simulation results, the approximate fatigue life of damaged MDI was calculated.Unapređenja u proizvodnji mini dentalnih implantata (MDI) su uglavnom usmerena ka povećanju njihove biokompatibilnosti i, u isto vreme, izdržljivosti i bezbednosti, ali i ka smanjenju njihovih dimenzija u odnosu na postojeće implantate. Međutim, tokom ugradnje MDI-a može doći do njegovog loma ili nastanka prsline koja kasnije može prouzrokovati lom. Da bi se analiziralo širenje prsline u titanijumskom MDI-u, korišćeni su softveri za primenu metode konačnih elemenata (MKE) ANSYS v13 i FRANC3D v5. Korišćenjem FRANC3D programa izmodelirane su prsline različitih veličina i oblika na 3D geometriji MDI-a i izvršeno je simuliranje njihovog širenja. Na osnovu rezultata simulacije izračunat je približan zamorni vek oštećenog MDI-a

Aerodynamic-structural optimization of aircraft lifting surfaces

Istraživanjem tokom izrade ove disertacije sprovedena je multidisciplinarna studija kojom je izvršeno numeričko modeliranje interakcije fluid-struktura uzgonskih poršina letelica. Numeričko modeliranje fenomena interakcije na relaciji fluid-struktura sprovedeno je posrednim sprezanjem aerodinamičkih i strukturalnih proračuna, a sa visokim stepenom pouzdanosti numeričkog predviđanja. Primenom predloženog algoritma postignuta je veća tačnost aerodinamičko-strukturalnih analiza u odnosu na postojeće postavke, dok je sama pouzdanost numeričkih proračuna utvrđena u odnosu na sprovedene aerodinamičke i strukturalne eksperimente. U okviru definisanih karakterističnih (kritičnih) režima tokom procesa eksploatacije, izvršen je izbor optimalnog aerodinamičkog oblika koji ispunjava taktičko-tehničke zahteve projektovanja, kao i propisana ograničenja, a na osnovu čega su aerodinamičko-strukturalne karakteristike letelice unapređene. Postupak optimizacije je baziran na korišćenju aproksimativnog modela, koji je opisan statističkim metodima, dok je sam optimajzer evolucionog tipa. Predloženo modularno okruženje predstavlja osnovni metod multidisciplinarne optimizacije opslužen od strane jedinstvenog optimajzera. U okviru kreiranog monolitičkog okruženja sprovedena je optimizacija krila balističkog projektila kratkog dometa. Metodom meta-modeliranja prostora pretrage značajno je povećan broj mogućih optimalnih geometrija koje zadovoljavaju i ciljeve i ogreničenja. Osnovni doprinos predstavlja aerodinamičko-strukturalno unapređivanje inicijalne geometrije analiziranog, realnog balističkog projektila. Optimizacijom su postojeće karakteristike i performanse projektila podignute na viši nivo, čime je u okviru realnih režima eksploatacije ostvareno povećanje finese, a time i dometa projektila, dok je sa aspekta sigurnosti pouzdanost samog projektila poboljšana. Ceo postupak je doprineo da troškovi razvojnog programa budu značajno umanjeni, a što se posebno ogleda u uštedama na polju eksperimentalnih i numeričkih resursa. Ostvarenim rezultatima analizirane letelice postignuti su realni uslovi za potencijalni razvoj jednog takvog raketnog sistema, a sam razvojni program je u mnogome unapređen i može poslužiti za razvoj i drugih letelica. Kreiranje numeričkog okruženja koje omogućava ovakav vid analize predstavlja značajan naučni i praktični doprinos pri spregnutom modeliranju ponašanja strukture izložene dejstvu fluida.In this research a multidisciplinary study of numerical modeling of fluidstructure interaction phenomenon was carried out. Numerical modeling of fluidstructure interaction of lifting surfaces was accomplished thru closely coupled aerodynamic and structural computational domains, with high computational reliability and accuracy which were established regarding conducted aerodynamic and structural experiments. The proposed algorithm gives better numerical accuracy of aerodynamicstructural analysis compared to existing similar methods. Multipoint and multidiscipline aerodynamic shape optimization, with respect to predefined objectives and constrains, was carried out in order to achieve the improvement of initial aerodynamic-structural performances of aircraft. The multidisciplinary feasible method proposed in this thesis, is a single level method driven by meta-modeling based evolutionary optimizer. The proposed monolithic environment was used for optimization of a realistic short range ballistic missile fin. This kind of analysis enabled increased number of feasible optimal geometries of fin, while its special feature was the overall improvement of ballistic missile initial geometry. Within realistic multipoint regimes, the initial performances of missile were optimized and upgraded, especially the missile fitness, and therefore range. At the same time, the reliability of missile overall behavior was improved. The whole procedure significantly decreased the costs of developing program, especially in use of experimental and numerical resources. The achieved results, regarding the ballistic missile, provide real conditions for potential development of such and similar aircrafts, with upgraded developing program. The established multimodular design optimization environment which enabled this kind of analysis presents significant scientific and practical contribution of fluid-structure interaction numerical modeling

freeCappuccino - An Open Source Software Library for Computational Continuum Mechanics

The paper describes development of an open-source library (www.github.com/nikola-m/freeCappuccino) for computational fluid dynamics and in general computational continuum mechanics. The code is based on finite volume method on arbitrary unstructured polyhedral meshes. The interfaces to highly abstract data types such as arbitrary order tensor fields on discretized finite volume domains, and scalar and vector sparse linear systems resulting from finite volume discretization of partial differential equations are provided. Explicit manipulation of tensor fields through high level, highly abstract programming syntax is explained. Also, implicit operation over tensor fields pertinent to discretization of partial differential operators is provided and explained. The library is developed in modern version of Fortran. Code parallelization is achieved through domain decomposition and implemented using MPI and OpenMP. While avoiding the usual class syntax of object-oriented programming, the code has essentially object oriented design. Comparison is made with the well-known OpenFOAM library. The purpose of the ongoing development is providing researchers with a tool for easy transfer of mathematical operations of their physical models into functional and efficient simulation software based on finite volume method. The guiding principle of development is exchange of ideas and reproducibility in computational science in general

Numerical aerodynamic-thermal-structural analyses of missile fin configuration during supersonic flight conditions

Attention in this work is focused on aerodynamic heating and aero-thermo-mechanical analysis of fin type structures on the missile at supersonic flight. At high Mach number the heat due to friction between body and flow, i.e. viscous heating must be taken into account because the velocity field is coupled with the temperature field. The flow field around the fins of the missile and especially the temperature distribution on its surface, as well as aerodynamic-thermal-structural analyses are numerically modeled in ANSYS Workbench environment. The investigation was carried out for two Mach numbers (M = 2.3 and M = 3.7). Own available structural experimental results have been used for computational structural mechanics (CSM) validation and verification, in order to assure credibility of numerical fluid-thermal-structure interaction (FTSI). Conducted simulations were carried out to better understand the FTSIs of the missile fin during supersonic flight

Numerical Simulation of Crack Propagation in Seven-Wire Strand

This paper discusses certain aspects of numerical simulation of crack propagation in wire ropes subjected to axial loading, with the aim to explore and to demonstrate the capacity, performances and difficulties of crack propagation modeling by usage of numerical computational methods in such complex structures. For this purpose, the finite element method (FEM) was used, and 3D numerical analyses were performed in Ansys Workbench software. In order to validate and verify performed numerical modeling, crack growth rate based on calculated stress intensity factors (SIFs) along the crack fronts was obtained for the model for which experimental results could be found in the available literature. Finally, using the advanced modeling techniques, the parametric 3D model of seven-wire strand was analyzed. Conducted analysis showed that FEM could be a powerful tool for fatigue life predictions in order to reduce the need for experiments, which are still the only successful method for fatigue life estimation of wire ropes. © Springer Nature Switzerland AG 2020.In: Mitrovic N., Milosevic M., Mladenovic G. (eds) Computational and Experimental Approaches in Materials Science and Engineering. CNNTech 2018. Lecture Notes in Networks and Systems, vol 90. Springer, Cha