Title Određivanje opterećenja osnosimetričnih ljuski inverznom metodom
Title (english) Load determination for axisymmetric shell using inverse procedure
Author Ivan Badurina
Mentor Ivica Kožar (mentor)
Committee member Silvija Mrakovčić (predsjednik povjerenstva)
Committee member Neira Torić Malić (član povjerenstva)
Committee member Ivica Kožar (član povjerenstva)
Granter University of Rijeka Faculty of Civil Engineering Rijeka
Defense date and country 2018-09-24, Croatia
Scientific / art field, discipline and subdiscipline TECHNICAL SCIENCES Civil Engineering Supporting Structures
Abstract Ovim radom se želi ustanoviti utjecaj greške u mjerenjima pomaka konstrukcije na greške u određivanju opterećenja koje djeluju po visini nekog cjevastog stupa. Utvrđivanjem utjecaja greške mogu se provoditi pouzdanija određivanja intenziteta vanjskog opterećenja koja mogu djelovati u nekoj točki stupa i to na osnovi podataka o pomacima, geometriji i materijalu konstrukcije.
U radu se promatra slučaj osnosimetrične ljuske koji čini stup vjetroagregata. U te svrhe, cjelokupni rad je zasnovan u programskom paketu Mathcad. Ovdje će se primijeniti bitno drugačiji pristup problemu u odnosu na uobičajenu paradigmu u inženjerstvu; gdje se poznavajući opterećenja koja djeluju u nekom sistemu, računaju pomaci i deformacije istog sistema. Ovdje će se na temelju izmjerenih pomaka u odabranim točkama konstrukcije, odrediti opterećenja umnoškom pseudoinverza vektora mjerenja s vektorom izmjerenih pomaka konstrukcije.
Rezultati određivanja opterećenja bit će tako u određenim odstupanjima od stvarnih opterećenja; s kojima se prvotno provodi analiza ljuske kako bi se dobio podatak o pomacima modela ljuske. Modelski pomaci su ovdje bitni jer se na temelju njih formira vektor mjerenja. Dok se dodavanjem šuma u vrijednostima pomaka modela simuliraju izmjereni pomaci sa slučajnom greškom. Veličina slučajne greške u pomacima će tako dati različite vrijednosti opterećenja koja će biti u različitim odstupanjima od referentnih, tj. stvarnih opterećenja.
Opterećenje u pitanju je djelovanje vjetra koje je po svojoj naravi nesimetrična vrsta opterećenja čime se analiza ljuske proširuje s ortogonalnim funkcijama i razlaganjem na članove Fourierovog reda.
Najbolje korelacije sa stvarnim opterećenjem će pokazati ona rješenja koja imaju malu slučajnu grešku u pomacima kao i ona koja imaju veći broj točaka mjerenja te su pritom otpornija na veće devijacije slučajne greške.
Abstract (english) This work seeks to establish the impact of the errors in measurements of structural displacement in determination of the loads acting at the height of a cylinder pillar. By determining the impact of the error, more reliable determinations of the intensity of an external load can be made, all on the basis of data on displacements, geometry and construction material that act at some point on a pillar.
The thesis is examining the case of an axisymmetric shell that forms a wind turbine pillar. For this purpose, the entire work is based on the Mathcad program package. In this work, a substantially different approach to the problem is going to be taken compared to the usual paradigm in engineering; where the loads that act in a system are known, and where output data are displacements and deformations of the said system. Here, based on the measured displacements in selected points of the structure, loads will be determined by multiplying the pseudoinverse of the measurement vector with the vector array of measured displacements of the structure.
The results of the load determination will thus be in certain deviations from the actual loads; with which a shell analysis is initially carried out in order to get the data on the model displacements of the shell. Model displacements are essential here because, on their basis, the measurement vector is being formed. While simulated measured displacements with random error are made by adding a noise in model displacement values. The size of the random error in displacement will thus provide different load values that will be in different deviations from the reference, i.e. actual loads.
The load in question is the effect of wind activity, which is by its very nature an asymmetric load type, that requires the shell analysis to be expanded by the use of orthogonal functions and by decoupling them into Fourier series terms.
The load solutions that have small random displacement error will show the best correlations with the actual loads, as well as those that have larger amount of measurement data points, that are also more resistant to greater random error deviations.
Keywords
osnosimetrične ljuske
pseudoinverz
inverzna metoda
ortogonalne funkcije
Fourierov red
vjetroagregat
Keywords (english)
axisymmetric shells
pseudoinverse
inverse method
orthogonal functions
Fourier series
wind turbine
Language croatian
URN:NBN urn:nbn:hr:157:828378
Project Number: IPA 2007/HR/16 IPO/001-04051 Title: Centar izvrsnosti za procjenu stanja konstrukcija Acronym: CEEStructHealth Leader: Zdenko Tonković Jurisdiction: Croatia Funder: SAFU
Study programme Title: Civil Engineering; specializations in: Geotechnical Engineering, Hydraulic Engineering, Engineering Modelling, Structural Engineering, Transportation Engineering, Urban Engineering Course: Structural Engineering Study programme type: university Study level: graduate Academic / professional title: magistar/magistra inženjer/inženjerka građevinarstva (magistar/magistra inženjer/inženjerka građevinarstva)
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Created on 2018-11-22 08:46:14