17 KB399 KB16 KB200020262007Bonfoh, NapoLipinski, PaulTiem, Sonnouštevilka:24 straniletnik:41str. 77-80ISSN:1580-2949COBISSID:603050URN:URN:NBN:SI:doc-82IA2GBLenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijemehanske lastnostiplastičnostpolikristalni materialiutrjevanjeAnisotropic hardening of materials by non-shearable particles| Utrditev anizotropnih materialov z delci|A new description of the hardening of polycrystalline materials is proposed. This hardening is mainly induced by non-shearable particles. Anisotropic and kinematic hardening of this kind of material has been mentioned in a previous paper (Bonfoh et al., 2003). In contrast to this initial investigation, the proposed modified formulation introduces a non-linear hardening for the single crystal without particles and better renders the material behaviour at finite deformations. The micromechanical modelling is based on a two-level homogenization approach: a micro-mesoscopic transition is firstly performed to derive the equivalent behaviour of a single crystal containing a volume fraction of intra-crystalline particles. Then, a second transition to the macroscopic scale leads to the elastic-plastic behaviour of the polycrystalline material. The numerical results of the model are analysed in terms of the internal stress developed during plastic loading. The material behaviour, when subjected to a multiaxial loading, is also studied through the concept of the yield surface. Some other aspects, such as the influence of particles size, shape and volume fraction, are also investigatedPredložen je nov opis utrditve polikristalnih materialov. To utrditev povzročajo nestrižni delci. V prejšnjem delu je bila opisana anizotropična in kinematična utrditev materiala te vrste (Bonfoh in dr., 2003). Nasprotno od te začetne raziskave predložena modificirana formulacija uvaja nelinearno mikromehansko modeliranje za nanokristal brez delcev in bolje opisuje vedenje materiala pri končni deformaciji. Mikromehansko modeliranje temelji na približku dvostopenjske homogenizacije: mikro-mezoskopska tranzicija je uporabljena za opis ekvivalentnega vedenja monokristala, ki vsebuje neki prostorninski delež intrakristalnih delcev, nato pa tranzicija na makroskopsko merilo vodi v elasto- plastično vedenje polikristalnega materiala. Numerični rezultati modela so analizirani s stališča notranjih napetosti, ki nastanejo pri plastični obremenitvi. Vedenje materiala pri večosni obremenitvi je analizirano s stališča plastičnega popuščanja površine.Analizirani so tudi drugi vidiki, npr. vpliv velikosti oblike in prostorninskega deleža delcevTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije