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Title:TORZIJSKO ELASTIČNO IZRAVNAVANJE PRI PREOBLIKOVANJU PLOČEVIN Z VISOKO TRDNOSTJO
Authors:ID Deželak, Mihael (Author)
ID Pahole, Ivo (Mentor) More about this mentor... New window
ID Ficko, Mirko (Comentor)
Files:.pdf DR_Dezelak_Mihael_2014.pdf (9,01 MB)
MD5: E935C6A5C976CA5409A0F65863EEA5AA
 
Language:Slovenian
Work type:Dissertation
Typology:2.08 - Doctoral Dissertation
Organization:FS - Faculty of Mechanical Engineering
Abstract:Pojem elastično izravnavanje označuje spremembo geometrije pločevinastega izdelka po končanem preoblikovalnem procesu. Razčlenimo ga na kotno elastično izravnavanje, ukrivljenje stene in torzijsko elastično izravnavanje. Za slednjega, katerega analiza je temelj te disertacije, smo zaradi lažjega odčitavanja podali predlog izboljšane definicije. Glavni razlog torzijskega elastičnega izravnavanja so zaostale membranske napetosti, ki se pri parcialni analizi testnega izdelka (laserski izrez posameznih področij) kažejo kot ukrivljenje stene. Na robustnost končne geometrije izdelkov zaradi variiranja vrednosti torzijskega elastičnega izravnavanja v veliki meri vplivajo stohastične lastnosti pločevin. Simulacije po metodi končnih elementov so danes v fazi načrtovanja preoblikovalnega procesa pločevin nenadomestljivo orodje. Toda natančno napovedovanje elastičnega izravnavanja je kljub temu zelo težavno, saj je izdelek med preoblikovalnim procesom podvržen kompleksnemu razvoju deformacijskega stanja, poleg tega pa določitev vrednosti materialnih, tehnoloških in numeričnih parametrov izrazito vpliva na rezultate simulacij. Za rešitev tega problema je podan predlog metode izboljšanja napovedi na podlagi izvedbe numeričnih eksperimentov in vrednotenja odstopanja rezultatov simulacij od eksperimentalnih vrednosti. Na predstavljen način se je mogoče z računalniško simulacijo torzijskega elastičnega izravnavanja bolj približati rezultatom eksperimentov. Glavni potencial novega pristopa vidimo v podpori pri izvajanju geometrijskih korekcij na dejanskem orodju za doseganje zahtevanih toleranc izdelka.
Keywords:preoblikovanje pločevin, torzijsko elastično izravnavanje, pločevine z visoko trdnostjo, metoda končnih elementov, strojno učenje, metoda izboljšanja napovedi, načrtovanje eksperimentov, stohastična analiza, parcialna analiza
Place of publishing:[Maribor
Publisher:M. Deželak]
Year of publishing:2014
PID:20.500.12556/DKUM-44113 New window
UDC:519.2/.8:539.31:621.98(043.3)
COBISS.SI-ID:274181120 New window
NUK URN:URN:SI:UM:DK:GD6HB4K9
Publication date in DKUM:30.05.2014
Views:2334
Downloads:419
Metadata:XML DC-XML DC-RDF
Categories:KTFMB - FS
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Secondary language

Language:English
Title:TWIST SPRINGBACK AFTER FORMING OF HIGH STRENGTH SHEET METAL
Abstract:The term springback denotes the change of geometry of the sheet metal product after the forming process has been finished. The springback comprises the angular change, the sidewall curl and the twist. For the last one, the analysis of which is the base of this dissertation, we have suggested an improved definition in order to alleviate the reading of the twisting values. Residual in-plane stresses, which can be seen as a sidewall curl during the proposed partial analysis of the test product (laser cutting of specific areas), are the main cause of the twist springback. As the value of the twist springback varies, the robustness of the final geometry of products in a great extent depends on the stochastic characteristics of sheet metals. Today simulations using the finite element method are irreplaceable tools in forming process design. The exact springback prediction is, however, very difficult because the product is subject to complex development of deformation history during the forming process. Besides, the determination of material, technological and numerical parameters has a distinct impact on the simulation results. The proposition of the prediction improvement method on the basis of carrying out the Design of Numerical Experiments and the evaluation of the difference between the simulation results and experimental values is offered to solve this problem. Using a computer simulation of the twist springback the above mentioned method makes it possible to come nearer to the results of the experiments. The main potential of this new approach can be observed as a support to achieve the required tolerance of the product when performing geometrical corrections on physical forming tools.
Keywords:sheet metal forming, twist springback, high strength sheet metal, finite element method, machine learning, prediction improvement method, Design Of Experiments, stochastic analysis, partial analysis


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