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Vrednotenje termomehansko obremenjenih izdelkov z deformacijskim pristopom
Rosa, Uroš (Author), Nagode, Marko (Author), Fajdiga, Matija (Author)

URLURL - Presentation file, Visit http://www.dlib.si/details/URN:NBN:SI:doc-MSMM12QG New window

Abstract
Deformacijski pristop sodi med najbolj uveljavljene metode vrednotenja izdelkov, izpostavljenih utrujanju. Za njegovo uporabo pri termomehanskih obremenilnih stanjih in modeliranje lokalnih temperaturno-napetostno-deformacijskih stanj je uporabljen napetostno nadzorovan reološki model vzmet - drsnik s Prandtlovim operatorjem, ki omogoča modeliranje elastoplastičnih materialnih lastnosti. Postopek je razsirjen za uporabo na zahtevnih izdelkih v kombinaciji z metodo končnih elementov (MKE). Predstavljeni postopek vrednotenja se uvrsča med deljene postopke, pri katerih se ločeno določi napetostno-deformacijska stanja in ločeno izračuna poskodba. Za izračun je bil razvit program za izračun poškodbe(PIP), ki ima možnost uvoza rezultatov, pridobljenih z linearno ali nelinearno MKE analizo. Kritična mesta so določena z uporabo deformacijskih zdržljivostnih krivulj in Skeltonovega energijskega postopka. Materialni podatki so za neizmerjene temperature interpolirani z linearno ali odsekoma kubično Hermit-ovo metodo. Uporaba razvitega modela je prikazana na primeru dveh standardiziranih oblik preizkušancev za deformacijsko nadzorovane preizkuse pri nespremenljivem temperaturnem polju in za kombinacijo naključnega poteka temperaturne in mehanske obremenitve. Raziskana je tudi temperaturna odvisnost parametra Kp, ki je uporabljen v Neuberjevi formuli za oceno elastoplastičnih napetostno-deformacijskih stanj iz rezultatov linearne MKE analize. Predstavljen postopek omogoča računsko hitro vrednotenje izdelkov, obremenjenih z naključno kombinacijo temperaturne in mehanske obremenitve.

Language:Slovenian
Keywords:termomehansko utrujanje, poškodbe, deformacijski postopki vrednotenja, metode končnih elementov
Work type:Not categorized (r6)
Tipology:1.01 - Original Scientific Article
Organization:FS - Faculty of Mechanical Engineering
Year:2007
Publisher:Association of Mechanical Engineers and Technicians of Slovenia et al.
Number of pages:str. 605-620
Numbering:Letn. 53, št. 10
UDC:620.178.3
ISSN on article:0039-2480
COBISS.SI-ID:10330651 Link is opened in a new window
Views:464
Downloads:141
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Record is a part of a journal

Title:Strojniški vestnik
Shortened title:Stroj. vestn.
Publisher:Zveza strojnih inženirjev in tehnikov Slovenije [et al.], = Association of Mechanical Engineers and Technicians of Slovenia [et al.]
ISSN:0039-2480
COBISS.SI-ID:762116 New window

Secondary language

Language:English
Title:Evaluating thermo-mechanically loaded components using a strain-life approach
Abstract:
The strain-life approach is one of the most commonly used methods for evaluating component fatigue. In its application for thermo-mechanically load states and for modelling local temperature stress-strain states, we use a stress-controlled rheological spring-slider model with an operator of the Prandtl type, which makes it possible to model the elasto-plastic material properties. The approach is used to evaluate complex components in combination with the finite-element method (FEM). The described evaluation approach is classified as one of the non-unified procedures, where we can determine separately the stress-strain states and separately calculate the damage. For the damage calculation a Damage Calculation Program (DCP) was developed. It has the possibility to import the results acquired by linear or nonlinear FEM analysis. The critical areas are determined by using a deformation endurance curve and the Skelton approach. The material data on non-measured temperatures is interpolated with the linear or cubic Hermite method. The application of the developed model is shown on two standard-shapedtest specimens for deformation control tests in a constant temperature field and for a combination of the random temperature history and the mechanical load. The temperature dependence of the Kp parameter used in the Neuber formula for estimating the elasto-plastic stress-strain states fromthe results of the linear FEM analysis is also included in the research. The described procedure enables a fast numerical validation with a random combination of temperature and mechanical load.

Keywords:thermo-mechanical fatigue, damages, strain-life approach, finite element methods

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