Structure behavior analysis and diagnostic

U radu je dat opis primene razvijene metodologije analize i dijagnostike ponašanja strukture. Osnova analize predstavlja statički, dinamički i termički proračun primenom metode konačnih elemenata. Navedena metodologija obuhvata funkcije raspodele opterećenja, napona i energije deformisanja pri statičkom i termičkom proračunu. Pri dinamičkom proračun prisutna je raspodela potencijalne i kinetičke energije po glavnim oblicima oscilovanja. Razvijeni sopstveni softver KOMIPS (oko 30000 instrukcija) na PC platformi ima navedene proračune i funkcije. U radu je dat kratak opis matričnih jednačina navedenih analiza, kao i njihova primena.The paper describes application of developed methodology for analysis and diagnostic of structure behavior. The basement of the analysis represents static, dynamic and thermal estimation by FME. Presented methodology has functions of load, stress and deformation energy distribution in the structure at static and thermal calculation. Kinetic and potential energy distribution on main oscillating modes is determined at dynamic calculation. Own developed software KOMIPS (about 30000 computer lines) installed on PC platform support developed methodology. Paper gives brief description of matrix equations and their application in developed methodology

Structure behavior analysis and diagnostic

U radu je dat opis primene razvijene metodologije analize i dijagnostike ponašanja strukture. Osnova analize predstavlja statički, dinamički i termički proračun primenom metode konačnih elemenata. Navedena metodologija obuhvata funkcije raspodele opterećenja, napona i energije deformisanja pri statičkom i termičkom proračunu. Pri dinamičkom proračun prisutna je raspodela potencijalne i kinetičke energije po glavnim oblicima oscilovanja. Razvijeni sopstveni softver KOMIPS (oko 30000 instrukcija) na PC platformi ima navedene proračune i funkcije. U radu je dat kratak opis matričnih jednačina navedenih analiza, kao i njihova primena.The paper describes application of developed methodology for analysis and diagnostic of structure behavior. The basement of the analysis represents static, dynamic and thermal estimation by FME. Presented methodology has functions of load, stress and deformation energy distribution in the structure at static and thermal calculation. Kinetic and potential energy distribution on main oscillating modes is determined at dynamic calculation. Own developed software KOMIPS (about 30000 computer lines) installed on PC platform support developed methodology. Paper gives brief description of matrix equations and their application in developed methodology

Validation numerical modeling with 3D optical measurement of deformations of foldable plastic packaging buckling failure

Ovaj rad opisuje numeričku i eksperimentalnu metodologiju radi analize karakteristika iskrivljenosti površine materijala plastične ambalaže koja je tipičan predstavnik svoje snage u stvarnom životu. Eksperimenti su izvedeni sa 'GOM' opremom i 'ARAMIS' softverskom aplikacijom za moderno optičko 3D merenje deformacija. Numerička analiza je izvedena primenom konačnih elemenata korišćenjem 'KOMIPS' softvera. Osnovno pitanje na koje je trebalo da se odgovori se odnosi na mehanizam deformacije sklopive ambalaže - da li iskrivljenost prethodi plastičnosti ili obrnuto? Ovaj članak će pokazati kako eksperimentalni rezultati mogu da se predvide pomoću analize konačnih elemenata; nađeno je da je ovo veoma snažna alatka u obrazovanju koja će omogućiti projektantima da poboljšaju konstruktivnu čvrstoću novih proizvoda u budućnosti. Rezultati eksperimentalne i numeričke analize do danas su pokazali visok stepen korelacije. Ovaj rad opisuje pristup koji dozvoljava dijagnosticiranje ponašanja stvarne konstrukcije; pouzdano očekivanje za reagovanje konstrukcije prilikom korišćenja, dobijene elemente radi različitih odlučivanja (radni režim, adaptacija, rekonstrukcije, revitalizacije, optimizacija, potvrđivanje prema odabiru promenjivih rešenja i tako dalje), definisanje uzoraka sa lošim performansama ili popuštanje konstrukcija, procena veka trajanja konstrukcije i slično. Pristup opisanoj razvijenoj dijagnozi je pokazan u rešenim primerima.This paper describes the numerical and experimental methodology for analysis of plastic packaging buckling characteristics that are representative of its strength in the real life. The experiments were executed with 'GOM' equipment and 'ARAMIS' software application for modern optical 3D measurement of deformations. Numerical analysis was conducted by the application of finite elements using 'KOMIPS' software. The fundamental question to be answered is related to the mechanism of failure of foldable packaging - does the buckling precede plasticity or vice versa? This article will show how experimental results can be predicted by means of finite element analysis; this is found a very strong learning tool that would enable designers to improve the structural strength of the new products in future. Experimental and numerical analysis results to date have shown high degree of correlation. This paper describes the access that allows real structure behavior diagnostic, reliable prospect for structure in exploitation reacting, elements receiving for different decision making (operating regime, rehabilitation, reconstructions, revitalizations, optimization, confirmation to variable solution selection and so on), poor performance sample defining or structure loosening, structure life time estimation and similar. The described developed diagnosis access is shown in solved examples

The influence of the nonlinear temperature field on the behavior of the metallic plate induced by two electromagnetic waves obtained by GSP

U radu su prikazani rezultati istraživanja ponašanja elastične metalne ploče proizvedenog pomoću dva harmonijska elektromagnetna ravna talasa (jedan sa donje, a drugi sa gornje površi ploče). Pravci prostiranja oba talasa su upravni na ravan ploče (osa x3). U rezultatu vremenske promene elektromagnetnog polja javlja se struja. Temperaturno polje je pretpostavljeno u vidu nelinearne funkcije po koordinati u pravcu debljine ploče. Ponašanje sistema je opisano pomoću sistema od tri spregnute jednačine, koje su rešene za stacionarno stanje korišćenjem integralnih transformacija (dvostrukih konačnih Fourier-ovih transformacija). Polje napona i deformacija je dobijeno korišćenjem MKE za neke slučajeve. Razmotrene su strukture koje imaju simetrična svojstva i problem je analiziran korišćenjem grupne supermatrične procedure korišćenjem GSP metode koju je razvio Zloković. Upoređivani su rezultati dobijeni pomoću GSP kao i MKE analize.In the paper the behavior of the elastic metallic plate produced by two harmonic electromagnetic plane waves (one at the upper and the other at the lower surface) is considered. Direction of the propagation of the both waves is normal on the surfaces of the plate (axe x3). As a result of time-changing electromagnetic field conducting currents appear. Distribution of the power of the eddy-current losses across the plate thickness is obtained using complex calculation. It is of exponential type and depends of the plate thickness, wave frequency, electric conductivity, magnetic permeability and magnetic intensity. In further consideration that power is treated as a volume heat source. So, temperature field across the plate thickness is assumed in nonlinear form as è(x1,x2,t)= ô0(x1,x2,t) ô1(x1,x2,t)x3+ ô2(x1,x2,t)x3 2 and the system of three coupled differential equations governing temperature field is formed. Equations are solved in analytical form for the stationary state using by integral transform technique (Double Finite Fourier transform). Strain and stress fields are obtained using by FEM for several cases of support position. As the considered structure has symmetry properties, the problem is analyzed using by group supermatrix procedure in the direct stiffness method (GSP) developed by Zlokovic. Performances of GSP are compared with those of the standard finite element analysis (FEM)

The influence of the nonlinear temperature field on the behavior of the metallic plate induced by two electromagnetic waves obtained by GSP

U radu su prikazani rezultati istraživanja ponašanja elastične metalne ploče proizvedenog pomoću dva harmonijska elektromagnetna ravna talasa (jedan sa donje, a drugi sa gornje površi ploče). Pravci prostiranja oba talasa su upravni na ravan ploče (osa x3). U rezultatu vremenske promene elektromagnetnog polja javlja se struja. Temperaturno polje je pretpostavljeno u vidu nelinearne funkcije po koordinati u pravcu debljine ploče. Ponašanje sistema je opisano pomoću sistema od tri spregnute jednačine, koje su rešene za stacionarno stanje korišćenjem integralnih transformacija (dvostrukih konačnih Fourier-ovih transformacija). Polje napona i deformacija je dobijeno korišćenjem MKE za neke slučajeve. Razmotrene su strukture koje imaju simetrična svojstva i problem je analiziran korišćenjem grupne supermatrične procedure korišćenjem GSP metode koju je razvio Zloković. Upoređivani su rezultati dobijeni pomoću GSP kao i MKE analize.In the paper the behavior of the elastic metallic plate produced by two harmonic electromagnetic plane waves (one at the upper and the other at the lower surface) is considered. Direction of the propagation of the both waves is normal on the surfaces of the plate (axe x3). As a result of time-changing electromagnetic field conducting currents appear. Distribution of the power of the eddy-current losses across the plate thickness is obtained using complex calculation. It is of exponential type and depends of the plate thickness, wave frequency, electric conductivity, magnetic permeability and magnetic intensity. In further consideration that power is treated as a volume heat source. So, temperature field across the plate thickness is assumed in nonlinear form as è(x1,x2,t)= ô0(x1,x2,t) ô1(x1,x2,t)x3+ ô2(x1,x2,t)x3 2 and the system of three coupled differential equations governing temperature field is formed. Equations are solved in analytical form for the stationary state using by integral transform technique (Double Finite Fourier transform). Strain and stress fields are obtained using by FEM for several cases of support position. As the considered structure has symmetry properties, the problem is analyzed using by group supermatrix procedure in the direct stiffness method (GSP) developed by Zlokovic. Performances of GSP are compared with those of the standard finite element analysis (FEM)

Razvijena procedura za strukturalnu dinamičku reanalizu

Structural dynamic modification techniques can be defined as methods by which dynamic behavior of a structure is improved by predicting the modified behavior brought about by adding modifications like those of lumped masses, rigid links, dampers, beams etc. or by variations in the configuration parameters of the structure itself. The methods of structural dynamic modification, especially those with their roots in finite element models, have often been described as reanalysis. The present paper deals with the problem of improving of dynamic characteristics some structures. New dynamic modification procedure is given as using distribution of potential and kinetic energy in every finite element is used for analysis. The main goal of dynamic modification is to increase natural frequencies and to increase the difference between them. Some information should be prepared, before setting up the FE model. The first pack of information includes referent peaces of information about the structure: size, material, and boundary conditions.U ovom radu je razvijena procedura za popravljanje dinamičkog ponašanja strojarskih konstrukcija u eksploataciji. U osnovi ove procedure je distribucija kinetičke i potencijalne energije na glavnim oblicima osciliranja konstrukcije. Inače, tehnika strukturne dinamičke modifikacije može se definirati kao skup metoda pomoću kojih se dinamičko ponašanje konstrukcije može popraviti procjenom modificiranog ponašanja dobivenog dodavanjem modifikacija kao na primjer koncentriranih masa, krutih veza, prigušenja, novih elemenata, i sl. ili promjenom konfiguracijskih parametara u samoj strukturi. Takve metode kod kojih je osnova metoda konačnih elemenata često se nazivaju metode reanalize. Jedan od osnovnih ciljeva u ovom radu, s obzirom na gore spomenuto, jest da se u metode reanalize ugradi još jedna s jasno predstavljenom procedurom korištenja

Temperature loading of a thin metallic plate subjected transversal to law-frequency electromagnetic field

Pošto mnoge konstrukcije tipa magnetskih kola elektromotora, generatora, induktora ili transformatora rade pod uticajem elektromagnetskih polja, u radu je prikazano određivanje Džulove toplote kao termičkog opterećenja tanke metalne ploče. Ploča je postavljena transverzalno u odnosu na homogeno vremenski promenljivo elektromagnetsko polje. Pravac prostiranja polja je upravan na srednju ravan ploče. Debljina ploče je mala u poređenju sa dubinom prodiranja magnetnog polja. Vremenski promenljivo elektromagnetno polje dovodi do pojave kondukcionih struja u materijalu ploče. Problem je rešen u analitičkom obliku kao unutrašnji Dirihleov granični problem. Intenzitet toplotnog opterećenja ploče određen je u dinamičkom obliku primenom tehnike integralnih transformacija (dvostruke konačne sinusne Furijeove transformacije i Laplasove transformacije). On zavisi od debljine ploče, električne provodnosti materijala, magnetske permeabilnosti, frekvencije i indukcije spoljašnjeg magnetnog polja, impulsnog ciklusa... Razmatran je uticaj dimenzija ploče, frekvencije polja i karakterističnih vremena impulsa na dinamičko termičko opterećenje ploče. Tako definisano termičko opterećenje predstavlja ulazni podatak za određivanje ponašanja ploče (napon, deformacija), koje se uobičajeno određuje primenom metode konačnih elemenata.Since many devices (such as magnetic circuits of motors, generators, inductors, transformers) work under the influence of the electromagnetic fields, obtaining Joule's heat as a thermal loading of the thin metallic plate subjected transversal in homogenous, time-varying electromagnetic field is presented in this paper. The direction of the field propagation is normal to the surfaces of the plate. Plate thickness is small compared to the depth of penetration of the magnetic field. Time-varying electromagnetic field is the reason of the conducting currents appearance in the material. The problem is solved in analytical form as the interior Dirichlet boundary problem. The intensity of thermal loading of the plate is obtained in dynamic form using the integral-transformation technique (Double Fourier finite-sine transformation and Laplace transformation). It depends on the plate thickness, electric conductivity, magnetic permeability, frequency and magnetic intensity of the external electromagnetic field, impulse's cycle... The influence of the plate thickness, field frequency and characteristic times of an impulse on the dynamic thermal loading are considered. Thermal loading is the entrance for the further calculation of the behavior of the plate, which is usually done by FEM

Analiza stanja, dijagnostika ponašanja, procena preostale čvrstoće i radnog veka, revitalizacija - integritet konstrukcije

Integritet konstrukcije je relativno nova naučna i inženjerska disciplina, koja obuhvata analizu stanja i dijagnostiku ponašanja i popuštanja, procenu preostale čvrstoće i radnog veka i revitalizaciju konstrukcije. Analiza stanja i dijagnostika ponašanja konstrukcije objekta izvodi se na računaru primenom numeričke metode konačnih elemenata razvijenim sistemom kompjuterskog modeliranja i proračuna struktura 'KOMIPS'. Ovaj pristup omogućava određivanje stvarnog ponašanja konstrukcije objekta, pouzdanu prognozu reagovanja konstrukcije u eksploataciji, dobijanje parametara izbora i odluka, određivanje uzroka lošeg ponašanja ili popuštanja konstrukcije, procenu eksploatacionog veka i vremena pouzdanog rada konstrukcije. Problemi nastali u eksploataciji opreme prvenstveno potiču od nedovoljno dobro projektovane geometrije. Osim toga, oni su često posledica nedovoljne otpornosti materijala, a posebno zavarenih spojeva, na nastanak i rast prslina. Takođe, čest je slučaj da su oba navedena faktora prisutna. U inženjerskoj analizi nosećih konstrukcija primena izložene metodologije nameće sa kao neminovnost. Ona ima opravdanja zbog vrlo niskih troškova primene uz vrlo visok nivo rezultata

Stress Analysis of a Pipeline as a Hydropower Plant Structural Element

This paper describes pipeline stress analysis, primarilybranch junctions, as a structural element in hydro-power plants. Pipelines are exposed to internal pressure,which is present under working conditions. Analysis of stresses in the pipeline of the hydropower plant is based on analytical, numerical, and experimental methods In this paper, we will define the critical elements of the pipeline. After that, we will determine critical areas in the branch junction, under experimental conditions, where strain gauges should be installed. The obtained resultsshow that a boiler formula can be efficiently applied in the stress analysis. Also, a correlation between the internal pressure and the maximum circumferential stresses in the elastic zone is given. In the final sections of the paper, the limit value of the internal pressure as a load for which stress in the zone of plasticity appears and the safety factor of the branch junction in the exploitation conditions are determined. The contribution of this work is the unification and deepening of the topic related to the problem of the testing othydro-power structural elements

Stress Analysis of a Pipeline as a Hydropower Plant Structural Element

This paper describes pipeline stress analysis, primarilybranch junctions, as a structural element in hydro-power plants. Pipelines are exposed to internal pressure,which is present under working conditions. Analysis of stresses in the pipeline of the hydropower plant is based on analytical, numerical, and experimental methods In this paper, we will define the critical elements of the pipeline. After that, we will determine critical areas in the branch junction, under experimental conditions, where strain gauges should be installed. The obtained resultsshow that a boiler formula can be efficiently applied in the stress analysis. Also, a correlation between the internal pressure and the maximum circumferential stresses in the elastic zone is given. In the final sections of the paper, the limit value of the internal pressure as a load for which stress in the zone of plasticity appears and the safety factor of the branch junction in the exploitation conditions are determined. The contribution of this work is the unification and deepening of the topic related to the problem of the testing othydro-power structural elements