Kojić, Miloš

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  • Kojić, Miloš (4)
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Author's Bibliography

Preparation and modeling of three-layered PCL/PLGA/PCL fibrous scaffolds for prolonged drug release

Milosević, Miljan; Stojanović, Dušica; Simić, Vladimir; Grković, Mirjana; Bjelović, Miloš; Uskoković, Petar; Kojić, Miloš

(Nature Publishing Group, London, 2020)

TY  - JOUR
AU  - Milosević, Miljan
AU  - Stojanović, Dušica
AU  - Simić, Vladimir
AU  - Grković, Mirjana
AU  - Bjelović, Miloš
AU  - Uskoković, Petar
AU  - Kojić, Miloš
PY  - 2020
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/4388
AB  - The authors present the preparation procedure and a computational model of a three-layered fibrous scaffold for prolonged drug release. The scaffold, produced by emulsion/sequential electrospinning, consists of a poly(d,l-lactic-co-glycolic acid) (PLGA) fiber layer sandwiched between two poly(epsilon -caprolactone) (PCL) layers. Experimental results of drug release rates from the scaffold are compared with the results of the recently introduced computational finite element (FE) models for diffusive drug release from nanofibers to the three-dimensional (3D) surrounding medium. Two different FE models are used: (1) a 3D discretized continuum and fibers represented by a simple radial one-dimensional (1D) finite elements, and (2) a 3D continuum discretized by composite smeared finite elements (CSFEs) containing the fiber smeared and surrounding domains. Both models include the effects of polymer degradation and hydrophobicity (as partitioning) of the drug at the fiber/surrounding interface. The CSFE model includes a volumetric fraction of fibers and diameter distribution, and is additionally enhanced by using correction function to improve the accuracy of the model. The computational results are validated on Rhodamine B (fluorescent drug l) and other hydrophilic drugs. Agreement with experimental results proves that numerical models can serve as efficient tools for drug release to the surrounding porous medium or biological tissue. It is demonstrated that the introduced three-layered scaffold delays the drug release process and can be used for the time-controlled release of drugs in postoperative therapy.
PB  - Nature Publishing Group, London
T2  - Scientific Reports
T1  - Preparation and modeling of three-layered PCL/PLGA/PCL fibrous scaffolds for prolonged drug release
IS  - 1
VL  - 10
DO  - 10.1038/s41598-020-68117-9
ER  - 
@article{
author = "Milosević, Miljan and Stojanović, Dušica and Simić, Vladimir and Grković, Mirjana and Bjelović, Miloš and Uskoković, Petar and Kojić, Miloš",
year = "2020",
abstract = "The authors present the preparation procedure and a computational model of a three-layered fibrous scaffold for prolonged drug release. The scaffold, produced by emulsion/sequential electrospinning, consists of a poly(d,l-lactic-co-glycolic acid) (PLGA) fiber layer sandwiched between two poly(epsilon -caprolactone) (PCL) layers. Experimental results of drug release rates from the scaffold are compared with the results of the recently introduced computational finite element (FE) models for diffusive drug release from nanofibers to the three-dimensional (3D) surrounding medium. Two different FE models are used: (1) a 3D discretized continuum and fibers represented by a simple radial one-dimensional (1D) finite elements, and (2) a 3D continuum discretized by composite smeared finite elements (CSFEs) containing the fiber smeared and surrounding domains. Both models include the effects of polymer degradation and hydrophobicity (as partitioning) of the drug at the fiber/surrounding interface. The CSFE model includes a volumetric fraction of fibers and diameter distribution, and is additionally enhanced by using correction function to improve the accuracy of the model. The computational results are validated on Rhodamine B (fluorescent drug l) and other hydrophilic drugs. Agreement with experimental results proves that numerical models can serve as efficient tools for drug release to the surrounding porous medium or biological tissue. It is demonstrated that the introduced three-layered scaffold delays the drug release process and can be used for the time-controlled release of drugs in postoperative therapy.",
publisher = "Nature Publishing Group, London",
journal = "Scientific Reports",
title = "Preparation and modeling of three-layered PCL/PLGA/PCL fibrous scaffolds for prolonged drug release",
number = "1",
volume = "10",
doi = "10.1038/s41598-020-68117-9"
}
Milosević, M., Stojanović, D., Simić, V., Grković, M., Bjelović, M., Uskoković, P.,& Kojić, M.. (2020). Preparation and modeling of three-layered PCL/PLGA/PCL fibrous scaffolds for prolonged drug release. in Scientific Reports
Nature Publishing Group, London., 10(1).
https://doi.org/10.1038/s41598-020-68117-9
Milosević M, Stojanović D, Simić V, Grković M, Bjelović M, Uskoković P, Kojić M. Preparation and modeling of three-layered PCL/PLGA/PCL fibrous scaffolds for prolonged drug release. in Scientific Reports. 2020;10(1).
doi:10.1038/s41598-020-68117-9 .
Milosević, Miljan, Stojanović, Dušica, Simić, Vladimir, Grković, Mirjana, Bjelović, Miloš, Uskoković, Petar, Kojić, Miloš, "Preparation and modeling of three-layered PCL/PLGA/PCL fibrous scaffolds for prolonged drug release" in Scientific Reports, 10, no. 1 (2020),
https://doi.org/10.1038/s41598-020-68117-9 . .
52
17
46

A Computational Model for Drug Release from PLGA Implant

Milosević, Miljan; Stojanović, Dušica; Simić, Vladimir; Milicević, Bogdan; Radisavljević, Anđela; Uskoković, Petar; Kojić, Miloš

(MDPI, Basel, 2018)

TY  - JOUR
AU  - Milosević, Miljan
AU  - Stojanović, Dušica
AU  - Simić, Vladimir
AU  - Milicević, Bogdan
AU  - Radisavljević, Anđela
AU  - Uskoković, Petar
AU  - Kojić, Miloš
PY  - 2018
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/3912
AB  - Due to the relative ease of producing nanofibers with a core-shell structure, emulsion electrospinning has been investigated intensively in making nanofibrous drug delivery systems for controlled and sustained release. Predictions of drug release rates from the poly (D, L-lactic-co-glycolic acid) (PLGA) produced via emulsion electrospinning can be a very difficult task due to the complexity of the system. A computational finite element methodology was used to calculate the diffusion mass transport of Rhodamine B (fluorescent drug model). Degradation effects and hydrophobicity (partitioning phenomenon) at the fiber/surrounding interface were included in the models. The results are validated by experiments where electrospun PLGA nanofiber mats with different contents were used. A new approach to three-dimensional (3D) modeling of nanofibers is presented in this work. The authors have introduced two original models for diffusive drug release from nanofibers to the 3D surrounding medium discretized by continuum 3D finite elements: (1) A model with simple radial one-dimensional (1D) finite elements, and (2) a model consisting of composite smeared finite elements (CSFEs). Numerical solutions, compared to experiments, demonstrate that both computational models provide accurate predictions of the diffusion process and can therefore serve as efficient tools for describing transport inside a polymer fiber network and drug release to the surrounding porous medium.
PB  - MDPI, Basel
T2  - Materials
T1  - A Computational Model for Drug Release from PLGA Implant
IS  - 12
VL  - 11
DO  - 10.3390/ma11122416
ER  - 
@article{
author = "Milosević, Miljan and Stojanović, Dušica and Simić, Vladimir and Milicević, Bogdan and Radisavljević, Anđela and Uskoković, Petar and Kojić, Miloš",
year = "2018",
abstract = "Due to the relative ease of producing nanofibers with a core-shell structure, emulsion electrospinning has been investigated intensively in making nanofibrous drug delivery systems for controlled and sustained release. Predictions of drug release rates from the poly (D, L-lactic-co-glycolic acid) (PLGA) produced via emulsion electrospinning can be a very difficult task due to the complexity of the system. A computational finite element methodology was used to calculate the diffusion mass transport of Rhodamine B (fluorescent drug model). Degradation effects and hydrophobicity (partitioning phenomenon) at the fiber/surrounding interface were included in the models. The results are validated by experiments where electrospun PLGA nanofiber mats with different contents were used. A new approach to three-dimensional (3D) modeling of nanofibers is presented in this work. The authors have introduced two original models for diffusive drug release from nanofibers to the 3D surrounding medium discretized by continuum 3D finite elements: (1) A model with simple radial one-dimensional (1D) finite elements, and (2) a model consisting of composite smeared finite elements (CSFEs). Numerical solutions, compared to experiments, demonstrate that both computational models provide accurate predictions of the diffusion process and can therefore serve as efficient tools for describing transport inside a polymer fiber network and drug release to the surrounding porous medium.",
publisher = "MDPI, Basel",
journal = "Materials",
title = "A Computational Model for Drug Release from PLGA Implant",
number = "12",
volume = "11",
doi = "10.3390/ma11122416"
}
Milosević, M., Stojanović, D., Simić, V., Milicević, B., Radisavljević, A., Uskoković, P.,& Kojić, M.. (2018). A Computational Model for Drug Release from PLGA Implant. in Materials
MDPI, Basel., 11(12).
https://doi.org/10.3390/ma11122416
Milosević M, Stojanović D, Simić V, Milicević B, Radisavljević A, Uskoković P, Kojić M. A Computational Model for Drug Release from PLGA Implant. in Materials. 2018;11(12).
doi:10.3390/ma11122416 .
Milosević, Miljan, Stojanović, Dušica, Simić, Vladimir, Milicević, Bogdan, Radisavljević, Anđela, Uskoković, Petar, Kojić, Miloš, "A Computational Model for Drug Release from PLGA Implant" in Materials, 11, no. 12 (2018),
https://doi.org/10.3390/ma11122416 . .
20
11
18

Biomaterijali

Balać, Igor; Bugarski, Branko; Ćosić, Irena; Dramićanin, Miroslav; Đorđević, Drago; Filipović, Nenad D.; Ignjatović, Nenad; Janaćković, Đorđe; Kojić, Miloš; Manojlović, Verica; Marković, Zoran; Obradović, Bojana; Pajić-Lijaković, Ivana; Pavlović, Miodrag; Plavšić, Milenko B.; Raković, Dejan; Ranković, Vladimir; Stojanović, Boban; Trajković, Vladimir; Uskoković, Dragan; Uskoković, Petar; Veljković, Dejan; Vlastelica, Ivo; Vunjak-Novaković, Gordana

(Beograd : Institut tehničkih nauka Srpske akademije nauka i umetnosti; Društvo za istraživanje materijala, 2010)

TY  - BOOK
AU  - Balać, Igor
AU  - Bugarski, Branko
AU  - Ćosić, Irena
AU  - Dramićanin, Miroslav
AU  - Đorđević, Drago
AU  - Filipović, Nenad D.
AU  - Ignjatović, Nenad
AU  - Janaćković, Đorđe
AU  - Kojić, Miloš
AU  - Manojlović, Verica
AU  - Marković, Zoran
AU  - Obradović, Bojana
AU  - Pajić-Lijaković, Ivana
AU  - Pavlović, Miodrag
AU  - Plavšić, Milenko B.
AU  - Raković, Dejan
AU  - Ranković, Vladimir
AU  - Stojanović, Boban
AU  - Trajković, Vladimir
AU  - Uskoković, Dragan
AU  - Uskoković, Petar
AU  - Veljković, Dejan
AU  - Vlastelica, Ivo
AU  - Vunjak-Novaković, Gordana
PY  - 2010
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/1535
AB  - Početak XXI veka nesumnjivo je obeležen interdisciplinarnim i multidisciplinarnim naporima istraživača u različitim oblastima nauke. Jedna od najizrazitijih tendencija ovog tipa uočava se u biomedicinskim istraživanjima, gde se združuju napori lekara, biologa, genetičara i biohemičara, s jedne strane, i biofizičara i inženjera, s druge strane – sa ciljem dubljeg razumevanja zdravlja i bolesti, i primene ovih saznanja u biomedicinskoj praksi, tako važnoj u svakodnevnom životu ljudi. Kao rezultat ovih svetskih trendova, u Srbiji već više godina na nekoliko fakulteta postoji nastava iz oblasti biomedicinskog inženjerstva, sa ciljem da osposobi inženjere ovih usmerenja za multidisciplinarno povezivanje znanja iz oblasti tehnike sa biomedicinskim znanjima. Jedan od bazičnih predmeta ovih usmerenja jesu Biomaterijali, kojima je i posvećen naš udžbenik, čiji je cilj da predstavi pregled teorije i prakse biomaterijala u biomedicinskoj nauci. Nauka o biomaterijalima je nesumnjivo najmultidisciplinarnija od svih nauka, jer zahteva ovladavanje znanjima iz mnogih oblasti nauke i tehnologije, inženjerstva i medicine, kako bi naučnici iz oblasti biomaterijala mogli da se uhvate u koštac sa ovom profesijom. Zato posle uvodnog dela, udžbenik iz Biomaterijala sadrži četiri celine: (I) Osnovni biomedicinski koncepti i reakcije organizma na biomaterijale, (II) Struktura, fizičko-mehanička karakterizacija i modeliranje biomaterijala i tkiva, (III) Savremeni biomaterijali i tehnologije, (IV) Perspektive biomaterijala i tehnologija, iza kojih slede Zadaci sa rešenjima, Ispitna test pitanja i Ispitna teorijska pitanja, koji pomažu studentima da lakše savladaju veoma obimno i kompleksno gradivo. Na kraju svakog poglavlja data su pitanja za rekapitulaciju, kao i spisak dopunske literature za opcionu detaljniju obradu pojedinih oblasti. Grupa od dvadeset četiri profesionalca sa univerziteta i naučnih instituta, pod okriljem Instituta tehničkih nauka Srpske akademije nauka i umetnosti, Beograd, i Društva za istraživanje materijala Srbije (MRS Srbija) doprinela je pisanju ovog kapitalnog udžbenika o biomaterijalima, prvog do sada na srpskom jeziku. Mada uključivanje veće grupe autora nužno dovodi do stilske neujednačenosti, ipak je oblast biomaterijala toliko multidisciplinarna da je ovakav pristup bio neophodan, kako uostalom pokazuju slična svetska iskustva sa uključivanjem i preko pedeset autora. Ipak urednici su se potrudili da koliko je to moguće stilski i pedagoški ujednače udžbenik, kako bi bio korisna literatura za sve studente diplomskih, master i doktorskih studija iz biomedicinskog inženjerstva u Srbiji i okruženju.
PB  - Beograd : Institut tehničkih nauka Srpske akademije nauka i umetnosti; Društvo za istraživanje materijala
T1  - Biomaterijali
UR  - https://hdl.handle.net/21.15107/rcub_vinar_7344
ER  - 
@book{
author = "Balać, Igor and Bugarski, Branko and Ćosić, Irena and Dramićanin, Miroslav and Đorđević, Drago and Filipović, Nenad D. and Ignjatović, Nenad and Janaćković, Đorđe and Kojić, Miloš and Manojlović, Verica and Marković, Zoran and Obradović, Bojana and Pajić-Lijaković, Ivana and Pavlović, Miodrag and Plavšić, Milenko B. and Raković, Dejan and Ranković, Vladimir and Stojanović, Boban and Trajković, Vladimir and Uskoković, Dragan and Uskoković, Petar and Veljković, Dejan and Vlastelica, Ivo and Vunjak-Novaković, Gordana",
year = "2010",
abstract = "Početak XXI veka nesumnjivo je obeležen interdisciplinarnim i multidisciplinarnim naporima istraživača u različitim oblastima nauke. Jedna od najizrazitijih tendencija ovog tipa uočava se u biomedicinskim istraživanjima, gde se združuju napori lekara, biologa, genetičara i biohemičara, s jedne strane, i biofizičara i inženjera, s druge strane – sa ciljem dubljeg razumevanja zdravlja i bolesti, i primene ovih saznanja u biomedicinskoj praksi, tako važnoj u svakodnevnom životu ljudi. Kao rezultat ovih svetskih trendova, u Srbiji već više godina na nekoliko fakulteta postoji nastava iz oblasti biomedicinskog inženjerstva, sa ciljem da osposobi inženjere ovih usmerenja za multidisciplinarno povezivanje znanja iz oblasti tehnike sa biomedicinskim znanjima. Jedan od bazičnih predmeta ovih usmerenja jesu Biomaterijali, kojima je i posvećen naš udžbenik, čiji je cilj da predstavi pregled teorije i prakse biomaterijala u biomedicinskoj nauci. Nauka o biomaterijalima je nesumnjivo najmultidisciplinarnija od svih nauka, jer zahteva ovladavanje znanjima iz mnogih oblasti nauke i tehnologije, inženjerstva i medicine, kako bi naučnici iz oblasti biomaterijala mogli da se uhvate u koštac sa ovom profesijom. Zato posle uvodnog dela, udžbenik iz Biomaterijala sadrži četiri celine: (I) Osnovni biomedicinski koncepti i reakcije organizma na biomaterijale, (II) Struktura, fizičko-mehanička karakterizacija i modeliranje biomaterijala i tkiva, (III) Savremeni biomaterijali i tehnologije, (IV) Perspektive biomaterijala i tehnologija, iza kojih slede Zadaci sa rešenjima, Ispitna test pitanja i Ispitna teorijska pitanja, koji pomažu studentima da lakše savladaju veoma obimno i kompleksno gradivo. Na kraju svakog poglavlja data su pitanja za rekapitulaciju, kao i spisak dopunske literature za opcionu detaljniju obradu pojedinih oblasti. Grupa od dvadeset četiri profesionalca sa univerziteta i naučnih instituta, pod okriljem Instituta tehničkih nauka Srpske akademije nauka i umetnosti, Beograd, i Društva za istraživanje materijala Srbije (MRS Srbija) doprinela je pisanju ovog kapitalnog udžbenika o biomaterijalima, prvog do sada na srpskom jeziku. Mada uključivanje veće grupe autora nužno dovodi do stilske neujednačenosti, ipak je oblast biomaterijala toliko multidisciplinarna da je ovakav pristup bio neophodan, kako uostalom pokazuju slična svetska iskustva sa uključivanjem i preko pedeset autora. Ipak urednici su se potrudili da koliko je to moguće stilski i pedagoški ujednače udžbenik, kako bi bio korisna literatura za sve studente diplomskih, master i doktorskih studija iz biomedicinskog inženjerstva u Srbiji i okruženju.",
publisher = "Beograd : Institut tehničkih nauka Srpske akademije nauka i umetnosti; Društvo za istraživanje materijala",
title = "Biomaterijali",
url = "https://hdl.handle.net/21.15107/rcub_vinar_7344"
}
Balać, I., Bugarski, B., Ćosić, I., Dramićanin, M., Đorđević, D., Filipović, N. D., Ignjatović, N., Janaćković, Đ., Kojić, M., Manojlović, V., Marković, Z., Obradović, B., Pajić-Lijaković, I., Pavlović, M., Plavšić, M. B., Raković, D., Ranković, V., Stojanović, B., Trajković, V., Uskoković, D., Uskoković, P., Veljković, D., Vlastelica, I.,& Vunjak-Novaković, G.. (2010). Biomaterijali. 
Beograd : Institut tehničkih nauka Srpske akademije nauka i umetnosti; Društvo za istraživanje materijala..
https://hdl.handle.net/21.15107/rcub_vinar_7344
Balać I, Bugarski B, Ćosić I, Dramićanin M, Đorđević D, Filipović ND, Ignjatović N, Janaćković Đ, Kojić M, Manojlović V, Marković Z, Obradović B, Pajić-Lijaković I, Pavlović M, Plavšić MB, Raković D, Ranković V, Stojanović B, Trajković V, Uskoković D, Uskoković P, Veljković D, Vlastelica I, Vunjak-Novaković G. Biomaterijali. 2010;.
https://hdl.handle.net/21.15107/rcub_vinar_7344 .
Balać, Igor, Bugarski, Branko, Ćosić, Irena, Dramićanin, Miroslav, Đorđević, Drago, Filipović, Nenad D., Ignjatović, Nenad, Janaćković, Đorđe, Kojić, Miloš, Manojlović, Verica, Marković, Zoran, Obradović, Bojana, Pajić-Lijaković, Ivana, Pavlović, Miodrag, Plavšić, Milenko B., Raković, Dejan, Ranković, Vladimir, Stojanović, Boban, Trajković, Vladimir, Uskoković, Dragan, Uskoković, Petar, Veljković, Dejan, Vlastelica, Ivo, Vunjak-Novaković, Gordana, "Biomaterijali" (2010),
https://hdl.handle.net/21.15107/rcub_vinar_7344 .

Micromechanism of ductile fracture initiation: Void nucleation and growth

Rakin, Marko; Cvijović, Zorica; Grabulov, Vencislav; Kojić, Miloš

(University of Niš, 2000)

TY  - JOUR
AU  - Rakin, Marko
AU  - Cvijović, Zorica
AU  - Grabulov, Vencislav
AU  - Kojić, Miloš
PY  - 2000
UR  - http://TechnoRep.tmf.bg.ac.rs/handle/123456789/319
AB  - Micromechanism of ductile fracture of most metals and alloys includes void nucleation, growth and coalescence. The voids nucleate at the second phase particles and non-metallic inclusions. Application of so-called global criteria of fracture mechanics such as COD and J-integral in characterization of ductile fracture onset does not provide satisfactory results for all cases of external loading. The problems arising in solving the phenomenon of severe plastic strain at crack tips and application of the results obtained to describe behaviour of various structures of different geometry are not insignificant. In present paper micromechanical model based on a particular criterion of flow in a porous solid has been applied. The model was initially established by Gurson, and later on modified by Tvergaard and Needleman. Unlike traditional flow criteria (for instance, with metals widely applied Von Mises criterion), established flow introduces volume fraction (f) variable. Through application of this model, by combining experimental and numerical procedures, an effort is made to predict ductile fracture of metals. In present paper fracture initiation of smooth specimen has been analyzed; described model was incorporated into finite element (FE) program, so that one of the results for each Gauss point may be void volume fraction as well. Probably the most difficult part of such a characterization of ductile fracture is to present physically void nucleation as accurately as possible. An approach to void nucleation, suggested by Chu and Needleman, has been discussed in this paper; the model is based on hypothesis that void nucleation follows a normal distribution of void formation predominantly around coarser non-metallic inclusions in steel. It is particularly problematic to examine secondary voids nucleation around smaller non-metallic inclusions and second phase particles, and to realize their effects on further growth of the existing (primary) voids, and especially on their coalescence resulting in fracture. This has been accompanied by adequate metallographic analysis of non-metallic inclusions and their volume fraction, which represents starting results for elastic-plastic analysis of a porous solid using FE method. The results obtained suggest that applied micromechanical model can be used for characterization of initiation of ductile fracture in steel on geometries -without precracks, and that metallurgical analysis is necessary to describe physically the first phase - void nucleation. Special contribution should represent application of the results obtained with a simple geometry to the precrached structures, which should be confirmed in work to follow. .
AB  - U radu su, polazeći od rezultata dobijenih numeričkim putem, koristeći pretpostavku o elastično-plastičnom telu, na standardnom kružnom uzorku od nisko legiranog čelika za sudove pod pritiskom, izvedeni sledeći zaključci: -razlika između GTN modela sa udelom zapreminske poroznosti uključenim u kriterijum strujanja i tradicionalnog Von Mises-ovog je mala: oba proračuna daju rezultate bliske eksperimentalnim -FE proračun koji koristi elemente sa osam čvorova omogućuje da se približno odredi dijagram zavisnosti tačke koalescencije pora od smanjenja prečnika -određivanje zapreminskog kritičnog udela poroznosti fc -procedura bi se trebalo proveriti kod oblika sa predprskotinama. .
PB  - University of Niš
T2  - Facta universitatis - series: Mechanical Engineering
T1  - Micromechanism of ductile fracture initiation: Void nucleation and growth
T1  - Mikromehanizam inicijalizacije daktilnih fraktura - nukleacija prskotina i njihov rast
EP  - 833
IS  - 7
SP  - 825
VL  - 1
UR  - https://hdl.handle.net/21.15107/rcub_technorep_319
ER  - 
@article{
author = "Rakin, Marko and Cvijović, Zorica and Grabulov, Vencislav and Kojić, Miloš",
year = "2000",
abstract = "Micromechanism of ductile fracture of most metals and alloys includes void nucleation, growth and coalescence. The voids nucleate at the second phase particles and non-metallic inclusions. Application of so-called global criteria of fracture mechanics such as COD and J-integral in characterization of ductile fracture onset does not provide satisfactory results for all cases of external loading. The problems arising in solving the phenomenon of severe plastic strain at crack tips and application of the results obtained to describe behaviour of various structures of different geometry are not insignificant. In present paper micromechanical model based on a particular criterion of flow in a porous solid has been applied. The model was initially established by Gurson, and later on modified by Tvergaard and Needleman. Unlike traditional flow criteria (for instance, with metals widely applied Von Mises criterion), established flow introduces volume fraction (f) variable. Through application of this model, by combining experimental and numerical procedures, an effort is made to predict ductile fracture of metals. In present paper fracture initiation of smooth specimen has been analyzed; described model was incorporated into finite element (FE) program, so that one of the results for each Gauss point may be void volume fraction as well. Probably the most difficult part of such a characterization of ductile fracture is to present physically void nucleation as accurately as possible. An approach to void nucleation, suggested by Chu and Needleman, has been discussed in this paper; the model is based on hypothesis that void nucleation follows a normal distribution of void formation predominantly around coarser non-metallic inclusions in steel. It is particularly problematic to examine secondary voids nucleation around smaller non-metallic inclusions and second phase particles, and to realize their effects on further growth of the existing (primary) voids, and especially on their coalescence resulting in fracture. This has been accompanied by adequate metallographic analysis of non-metallic inclusions and their volume fraction, which represents starting results for elastic-plastic analysis of a porous solid using FE method. The results obtained suggest that applied micromechanical model can be used for characterization of initiation of ductile fracture in steel on geometries -without precracks, and that metallurgical analysis is necessary to describe physically the first phase - void nucleation. Special contribution should represent application of the results obtained with a simple geometry to the precrached structures, which should be confirmed in work to follow. ., U radu su, polazeći od rezultata dobijenih numeričkim putem, koristeći pretpostavku o elastično-plastičnom telu, na standardnom kružnom uzorku od nisko legiranog čelika za sudove pod pritiskom, izvedeni sledeći zaključci: -razlika između GTN modela sa udelom zapreminske poroznosti uključenim u kriterijum strujanja i tradicionalnog Von Mises-ovog je mala: oba proračuna daju rezultate bliske eksperimentalnim -FE proračun koji koristi elemente sa osam čvorova omogućuje da se približno odredi dijagram zavisnosti tačke koalescencije pora od smanjenja prečnika -određivanje zapreminskog kritičnog udela poroznosti fc -procedura bi se trebalo proveriti kod oblika sa predprskotinama. .",
publisher = "University of Niš",
journal = "Facta universitatis - series: Mechanical Engineering",
title = "Micromechanism of ductile fracture initiation: Void nucleation and growth, Mikromehanizam inicijalizacije daktilnih fraktura - nukleacija prskotina i njihov rast",
pages = "833-825",
number = "7",
volume = "1",
url = "https://hdl.handle.net/21.15107/rcub_technorep_319"
}
Rakin, M., Cvijović, Z., Grabulov, V.,& Kojić, M.. (2000). Micromechanism of ductile fracture initiation: Void nucleation and growth. in Facta universitatis - series: Mechanical Engineering
University of Niš., 1(7), 825-833.
https://hdl.handle.net/21.15107/rcub_technorep_319
Rakin M, Cvijović Z, Grabulov V, Kojić M. Micromechanism of ductile fracture initiation: Void nucleation and growth. in Facta universitatis - series: Mechanical Engineering. 2000;1(7):825-833.
https://hdl.handle.net/21.15107/rcub_technorep_319 .
Rakin, Marko, Cvijović, Zorica, Grabulov, Vencislav, Kojić, Miloš, "Micromechanism of ductile fracture initiation: Void nucleation and growth" in Facta universitatis - series: Mechanical Engineering, 1, no. 7 (2000):825-833,
https://hdl.handle.net/21.15107/rcub_technorep_319 .