1677 KB37 KB199920252016Duran, DenizKaradogan, Celalettinletnik:62številka:nr. 4str. 243-251ISSN:0039-2480COBISSID_HOST:14595355URN:URN:NBN:SI:doc-PSQ2Y5LEenZveza strojnih inženirjev in tehnikov Slovenije etc.Strojniški vestnikdigitalna analiza posnetkovkoeficient Coulombovega trenjapreizkus s stiskanjem valjaspremenjena kontaktna površinaDetermination of coulomb's friction coefficient directly from cylinder compression tests|In this paper, a new method is proposed for the determination of Coulomb's friction coefficient directly from cylinder compression tests. It is based on measuring the immigrated contact area (ICA), which is defined as the lateral surface that comes into contact with the platens after deformation. Preliminary sensitivity analyses showed that ICA is only a function of friction and the strain-hardening exponent at room temperature when a power law relation between the true stress and the true plastic strain is considered. Through intensive numerical simulations by using a code-driven simulation environment, an inverse calculation is done which makes the determination of the friction coefficient possible by using ICA and the strain-hardening exponent of the investigated material. At the end of compression, ICA is usually clearly visible without any precautions; thus, a simplified script is supplied which calculates ICA through digital image analysis made on the end faces of the compressed specimens. This paper includes the complete procedure to determine Coulomb's friction coefficient and a script in which the proposed method is embedded entirely. In addition, practical case studies demonstrated the ease of applicability of the proposed method by employing different materialsRazvita je bila nova metoda za neposredno določitev koeficienta Coulombovega trenja pri aplikacijah kovanja v hladnem s preizkusi stiskanja valja. Pri klasičnem pristopu se meri deformirana neenakomerna oblika stisnjenega preizkušanca in meritve se nato primerjajo z rezultati kalibracijskih simulacij, ki pokrivajo različne koeficiente trenja. Klasični pristop je zelo zamuden in zahteva vnaprejšnje poznavanje krivulj tečenja materiala. Težave nastopijo zaradi nehomogene porazdelitve spremenljivk polja, ki so posledica trenja na stiku med ploščo in preizkušancem. Nova metoda odpravlja potrebo po podrobnem poznavanju krivulje tečenja ter lahko zamenja kalibracijske simulacije za vse materiale in koeficiente trenja s preprostim polinomskim metamodelomTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaUniverza v Ljubljani, Fakulteta za strojništvo