BEGIN:VCALENDAR VERSION:2.0 PRODID:-//CERN//INDICO//EN BEGIN:VEVENT SUMMARY:Computational and experimental modal analysis of the Lasta aircraf t DTSTART;VALUE=DATE-TIME:20101208T170000Z DTEND;VALUE=DATE-TIME:20101208T180000Z DTSTAMP;VALUE=DATE-TIME:20261009T233403Z UID:indico-event-38@indico.ipb.ac.rs DESCRIPTION:During designing and development of an aircraft prototype it i s required to be confirm that the aircraft is free from flutter in the ran ge of the designed speed. Wing\, ailerons\, stabilizer\, or whole aircraft flutter is a phenomenon of self-induced undamped oscillations begins of c oupling aerodynamic\, elastic and inertial forces at high flight speeds. F lutter is very dangerous because it can cause aircraft construction crash. This presentation presents Computational and Experimental Modal Analysis procedures that are applied during designing and examination of the LASTA prototype aircraft.\n\nComputational Modal Analysis is done by using Finit e Element Method. Main assemblies of the aircraft wing\, fuselage and stab ilizers are modeled and analyzed separate. While modeling main assemblies we took care of the real construction elastic and inertial characteristics representation. This presentation gives the results of Modal Analysis of the LASTA aircraft. Critical flutter speeds calculation is done according to these results.\n\nAfter the prototype manufacturing\, Experimental Moda l Analysis is required to obtain data that are more precise for further cr itical flutter speed calculation. Aircraft preparation\, testing method\, excitation position\, data acquisition and processing are presented in the presentation. Obtained results – modal frequencies\, damping and mode s hapes are presented\, too. According to these results final critical flutt er speed calculation is done. In addition\, the aircraft finite element mo del will be verified and fit (according to these results) for further use in the analysis of the aeroelastic phenomena and aircraft dynamic response .\n\n- - - - - - - - - - \n\nU procesu projektovanja i razvoja letelica zn ačajno mesto zauzima zadovoljenje zahteva da letelica bude bezbedna od po jave flatera u okviru upotrebnih brzina. Flater krila\, krilaca\, repova\, ili celog aviona je pojava samopobudnih neprigušenih oscilacija nastalih sprezanjem aerodinamičkih\, elastičnih i inercijalnih sila pri velikim brzinama leta. Flater je veoma opasan jer može da izazove lom konstrukcij e aviona. Da bi se kritične brzine flatera mogle pouzdano proceniti neoph odni su podaci modalne analize letelice. U ovoj prezentacije će biti pre dstavljeni postupci računske i eksperimentalne modalne analize koji su pr imenjeni u toku projektovanja i ispitivanja prototipa aviona LASTA.\n\nRa čunska modalna analiza je obavljena primenom metode konačnih elemenata. Posebno su modelirani i analizirani osnovni sklopovi konstrukcije aviona k rilo\, trup i repovi\, a zatim je od njih formiran model kompletnog aviona . Pri modeliranju osnovnih sklopova se vodilo računa da oni i po elastič nim i po inercijalnim karakteristikama predstave realnu konstrukciju. U pr ezentaciji su prikazani rezultati modalne analize kompletnog modela aviona . Na osnovu njih je dalje obavljen proračun kritičnih brzina flatera.\n\ nPosle izrade prototipa\, da bi se dobili što tačniji podaci za proraču n kritičnih brzina flatera\, obavezno se obavlja eksperimentalna modalna analiza. U prezentaciji je prikazana priprema aviona za ispitivanje\, izbo r metode ispitivanja\, način pobuđivanje\, prikupljanja i obrade podatak a. Predstavljeni su dobijeni rezultati - sopstvene frekvencije\, prigušen ja i sopstveni oblici oscilovanja. Na osnovu ovih rezultata se radi završ ni proračun kritičnih brzina flatera kao i podešavanje modela konačnih elemenata aviona kako bi on mogao da se koristi za dalje analize aeroelas tičnih pojava i dinamičkog odziva aviona.\n\nReferences\n\n[1] FELIPPA\, C.A.: Introduction to Finite Element Methods\, Department of Aerospace Eng ineering Sciences\, September 2006. \n[2] BATHE\,K.J.\, WILSON\,E.L.: Nume rical Methods in Finite Element Analysis\, Prentice-hall\, inc.\, Englewoo d Cliffs\, New Jersey\, 1976. \n[3] WILSON\,E.L.: Numerical Methods in Off shore Engineering\, John Wiley & Sons\, 1987. \n[4] WILKINSON\,J.H.: The A lgebric Eigenvalue Problem\, Clarendon press\, Oxford\, 1965. \n[5] OJALVO \,I.U.: Proper Use of Lanczos Vectors for Large Eigenvalue Problems\, Comp uters & Structures\, vol. 20\, No. 1-3\, 1985. \n[6] HUGHES\,T.J.R.: The F inite Element Method\, Static and Dynamic Finite Element Analysis\, Prenti ce Hall\, 1987. \n[7] FEDERAL AVIATION ADMINISTRATION: Advisory Circular\, Means of Compliance With Section 23.629-1B\, Flutter\, 2004 \n[8] HUTIN\, C.: Modal Analysis Using Appropriated Excitation Techniques\, Data Physics SA\, Voisins le Bretonneux\, France\, 2000. \n[9] WELARANTA\,S.: Advanced Data Acquisition and Signal Analysis Packages Can Enable Effective Ground Vibration Testing\, Aerospace Testing International\, May 2003. \n[10] PE ETERS\,B.\, HENDRICX\,W.\, DEBILLE\,J.\, CLIMENT\,H.: Modern Solutions for Ground Vibration Testing of Large Aircraft\, LMS International\, Leuven\, Belgium and EADS CASA\, Getafe\, Spain\, January 2009. \n[11] KOVAČEVIĆ \,P.\, DIMITRIJEVIĆ\,J.\, DEJANOVIĆ\, N.\, BANOVIĆ\,N.: Ispitivanje vib racija na zemlji aviona Lasta P1\, Vojnotehnički institut VS\, maj 2010. \n[12] KOVAČEVIĆ\,P.\, DIMITRIJEVIĆ\,J.: Obrada podataka sa ispitivanja vibracija na zemlji aviona Lasta P1\, Vojnotehnički institut VS\, maj 20 10.\n\nhttps://events.saifa.rs/event/38/ LOCATION:Mathematical Institute 301 F URL:https://events.saifa.rs/event/38/ END:VEVENT END:VCALENDAR