TY  - JOUR
AU  - Bošnjak, Srđan
AU  - Arsić, Miodrag
AU  - Savićević, Sreten
AU  - Milojević, Goran
AU  - Arsić, Dušan
PY  - 2016
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2433
AB  - This paper presents the results of the pulley fracture analysis. Experimental investigations confirmed that the chemical composition and basic mechanical properties of the pulley material, except the impact energy at a temperature of - 20 degrees C, meet the requirements of the corresponding standard. The impact energy value at the temperature of - 20 degrees C is for approximate to 45% lower than the prescribed value which has considerable influence on the appearance of the brittle fracture, especially having in mind the fact that the bucket wheel excavators operate at low temperatures. Metallographic examinations as well as magnetic particle inspections indicated that initial cracks in the welded joints occurred during the manufacture of the pulleys. Characteristic levels of the rope load cycle are obtained by using in-house software which includes the dynamic effects of the resistance-to-excavation. The FEA results pointed out that in the representative load cases the combinations of the mean stress and the alternating stress in the pulley critical zone lie considerably below the limit line of the modified Goodman's diagram. The conclusion, based on the presented results, is that the fracture of the pulley appeared as the result of the 'manufacturing-in' defects.
PB  - Polish Maintenance Soc, Lublin
T2  - Eksploatacja I Niezawodnosc-Maintenance and Reliability
T1  - Fracture analysis of the pulley of a bucket wheel boom hoist system
EP  - 163
IS  - 2
SP  - 155
VL  - 18
DO  - 10.17531/ein.2016.2.1
ER  - 

@article{
author = "Bošnjak, Srđan and Arsić, Miodrag and Savićević, Sreten and Milojević, Goran and Arsić, Dušan",
year = "2016",
abstract = "This paper presents the results of the pulley fracture analysis. Experimental investigations confirmed that the chemical composition and basic mechanical properties of the pulley material, except the impact energy at a temperature of - 20 degrees C, meet the requirements of the corresponding standard. The impact energy value at the temperature of - 20 degrees C is for approximate to 45% lower than the prescribed value which has considerable influence on the appearance of the brittle fracture, especially having in mind the fact that the bucket wheel excavators operate at low temperatures. Metallographic examinations as well as magnetic particle inspections indicated that initial cracks in the welded joints occurred during the manufacture of the pulleys. Characteristic levels of the rope load cycle are obtained by using in-house software which includes the dynamic effects of the resistance-to-excavation. The FEA results pointed out that in the representative load cases the combinations of the mean stress and the alternating stress in the pulley critical zone lie considerably below the limit line of the modified Goodman's diagram. The conclusion, based on the presented results, is that the fracture of the pulley appeared as the result of the 'manufacturing-in' defects.",
publisher = "Polish Maintenance Soc, Lublin",
journal = "Eksploatacja I Niezawodnosc-Maintenance and Reliability",
title = "Fracture analysis of the pulley of a bucket wheel boom hoist system",
pages = "163-155",
number = "2",
volume = "18",
doi = "10.17531/ein.2016.2.1"
}

Bošnjak, S., Arsić, M., Savićević, S., Milojević, G.,& Arsić, D.. (2016). Fracture analysis of the pulley of a bucket wheel boom hoist system. in Eksploatacja I Niezawodnosc-Maintenance and Reliability
Polish Maintenance Soc, Lublin., 18(2), 155-163.
https://doi.org/10.17531/ein.2016.2.1

Bošnjak S, Arsić M, Savićević S, Milojević G, Arsić D. Fracture analysis of the pulley of a bucket wheel boom hoist system. in Eksploatacja I Niezawodnosc-Maintenance and Reliability. 2016;18(2):155-163.
doi:10.17531/ein.2016.2.1 .

Bošnjak, Srđan, Arsić, Miodrag, Savićević, Sreten, Milojević, Goran, Arsić, Dušan, "Fracture analysis of the pulley of a bucket wheel boom hoist system" in Eksploatacja I Niezawodnosc-Maintenance and Reliability, 18, no. 2 (2016):155-163,
https://doi.org/10.17531/ein.2016.2.1 . .

TY  - JOUR
AU  - Bošnjak, Srđan
AU  - Gnjatović, Nebojša
AU  - Savićević, Sreten
AU  - Pantelić, Milorad P.
AU  - Milenović, Ivan Lj.
PY  - 2016
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2424
AB  - Determining a bucket wheel excavator (BWE)'s slewing superstructure weight and its center of gravity (COG) is of extreme importance not only in the design phase, but also after the completion of the erection process and during the operation of the machine. This paper presents a critical comparative analysis of the basic parameters of the static stability of a BWE 1600 superstructure, with the parameters being obtained by both analytical and experimental procedures. The analysis shows that a relatively small difference in superstructure mass, obtained by calculation, leads to a relatively large unfavorable shifting of its COG, necessitating a significant increase in counterweight mass for balancing. A procedure for superstructure 3D model mass correction is presented based on results obtained by weighing after the completion of the erection process. The developed model provides enough accuracy to determine the superstructure's COG in the entire domain of the bucket wheel boom inclination angle, and enables accurate load analysis of the superstructure's vital parts. The importance of this analysis is reinforced by the finding that the procedure prescribed by standard DIN 22261-2 gives results which are not on the side of safety, as shown by an example of strength analysis of a bucket wheel boom stays' end eyes.
PB  - Zhejiang Univ, Hangzhou
T2  - Journal of Zhejiang University-Science A
T1  - Basic parameters of the static stability, loads and strength of the vital parts of a bucket wheel excavator's slewing superstructure
EP  - 365
IS  - 5
SP  - 353
VL  - 17
DO  - 10.1631/jzus.A1500037
ER  - 

@article{
author = "Bošnjak, Srđan and Gnjatović, Nebojša and Savićević, Sreten and Pantelić, Milorad P. and Milenović, Ivan Lj.",
year = "2016",
abstract = "Determining a bucket wheel excavator (BWE)'s slewing superstructure weight and its center of gravity (COG) is of extreme importance not only in the design phase, but also after the completion of the erection process and during the operation of the machine. This paper presents a critical comparative analysis of the basic parameters of the static stability of a BWE 1600 superstructure, with the parameters being obtained by both analytical and experimental procedures. The analysis shows that a relatively small difference in superstructure mass, obtained by calculation, leads to a relatively large unfavorable shifting of its COG, necessitating a significant increase in counterweight mass for balancing. A procedure for superstructure 3D model mass correction is presented based on results obtained by weighing after the completion of the erection process. The developed model provides enough accuracy to determine the superstructure's COG in the entire domain of the bucket wheel boom inclination angle, and enables accurate load analysis of the superstructure's vital parts. The importance of this analysis is reinforced by the finding that the procedure prescribed by standard DIN 22261-2 gives results which are not on the side of safety, as shown by an example of strength analysis of a bucket wheel boom stays' end eyes.",
publisher = "Zhejiang Univ, Hangzhou",
journal = "Journal of Zhejiang University-Science A",
title = "Basic parameters of the static stability, loads and strength of the vital parts of a bucket wheel excavator's slewing superstructure",
pages = "365-353",
number = "5",
volume = "17",
doi = "10.1631/jzus.A1500037"
}

Bošnjak, S., Gnjatović, N., Savićević, S., Pantelić, M. P.,& Milenović, I. Lj.. (2016). Basic parameters of the static stability, loads and strength of the vital parts of a bucket wheel excavator's slewing superstructure. in Journal of Zhejiang University-Science A
Zhejiang Univ, Hangzhou., 17(5), 353-365.
https://doi.org/10.1631/jzus.A1500037

Bošnjak S, Gnjatović N, Savićević S, Pantelić MP, Milenović IL. Basic parameters of the static stability, loads and strength of the vital parts of a bucket wheel excavator's slewing superstructure. in Journal of Zhejiang University-Science A. 2016;17(5):353-365.
doi:10.1631/jzus.A1500037 .

Bošnjak, Srđan, Gnjatović, Nebojša, Savićević, Sreten, Pantelić, Milorad P., Milenović, Ivan Lj., "Basic parameters of the static stability, loads and strength of the vital parts of a bucket wheel excavator's slewing superstructure" in Journal of Zhejiang University-Science A, 17, no. 5 (2016):353-365,
https://doi.org/10.1631/jzus.A1500037 . .

TY  - JOUR
AU  - Bošnjak, Srđan
AU  - Savićević, Sreten
AU  - Gnjatović, Nebojša
AU  - Milenović, Ivan Lj.
AU  - Pantelić, Milorad P.
PY  - 2015
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2224
AB  - A slope failure was the cause of a severe accident of bucket wheel excavator (BWE) Takraf SRs 1200. This paper is dedicated to the engineering challenges that accompanied the process of returning the BWE from its after accident state to the state of full exploitation readiness. After the accident, temporary stabilization of the superstructure was carried out as well as cutting off of severely damaged parts of the bucket wheel boom (BWB) with excavating device. Successful completion of the very delicate BWE rescue and balancing operation was followed by the reconstruction of the heavily damaged slewing platform. The integrity of the slewing platform structure was preserved by removing structural parts which were seriously damaged during long-term exploitation and breakdown, and installing the newly designed elements in critical zones. The redesign of the slewing platform structure produced favorable loads and stiffness distribution while eliminating geometrical stress concentrators. Comparative analyses of the stress states pointed out that the redesigned slewing platform structure meets the strength criterion, unlike the original structure. The redesign solution enabled reconstruction in field conditions. This way the time of the reconstruction realization was drastically cut and losses due to the downtime of the machine were reduced several times over. After completing the slewing platform reconstruction, the newly manufactured BWB structural elements as well as the newly manufactured bucket wheel with drive were installed i.e. a partial revitalization of the BWE was done and by that the BWE's life was essentially prolonged.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Engineering Failure Analysis
T1  - Disaster of the bucket wheel excavator caused by extreme environmental impact: Consequences, rescue and reconstruction
EP  - 374
SP  - 360
VL  - 56
DO  - 10.1016/j.engfailanal.2015.01.002
ER  - 

@article{
author = "Bošnjak, Srđan and Savićević, Sreten and Gnjatović, Nebojša and Milenović, Ivan Lj. and Pantelić, Milorad P.",
year = "2015",
abstract = "A slope failure was the cause of a severe accident of bucket wheel excavator (BWE) Takraf SRs 1200. This paper is dedicated to the engineering challenges that accompanied the process of returning the BWE from its after accident state to the state of full exploitation readiness. After the accident, temporary stabilization of the superstructure was carried out as well as cutting off of severely damaged parts of the bucket wheel boom (BWB) with excavating device. Successful completion of the very delicate BWE rescue and balancing operation was followed by the reconstruction of the heavily damaged slewing platform. The integrity of the slewing platform structure was preserved by removing structural parts which were seriously damaged during long-term exploitation and breakdown, and installing the newly designed elements in critical zones. The redesign of the slewing platform structure produced favorable loads and stiffness distribution while eliminating geometrical stress concentrators. Comparative analyses of the stress states pointed out that the redesigned slewing platform structure meets the strength criterion, unlike the original structure. The redesign solution enabled reconstruction in field conditions. This way the time of the reconstruction realization was drastically cut and losses due to the downtime of the machine were reduced several times over. After completing the slewing platform reconstruction, the newly manufactured BWB structural elements as well as the newly manufactured bucket wheel with drive were installed i.e. a partial revitalization of the BWE was done and by that the BWE's life was essentially prolonged.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Engineering Failure Analysis",
title = "Disaster of the bucket wheel excavator caused by extreme environmental impact: Consequences, rescue and reconstruction",
pages = "374-360",
volume = "56",
doi = "10.1016/j.engfailanal.2015.01.002"
}

Bošnjak, S., Savićević, S., Gnjatović, N., Milenović, I. Lj.,& Pantelić, M. P.. (2015). Disaster of the bucket wheel excavator caused by extreme environmental impact: Consequences, rescue and reconstruction. in Engineering Failure Analysis
Pergamon-Elsevier Science Ltd, Oxford., 56, 360-374.
https://doi.org/10.1016/j.engfailanal.2015.01.002

Bošnjak S, Savićević S, Gnjatović N, Milenović IL, Pantelić MP. Disaster of the bucket wheel excavator caused by extreme environmental impact: Consequences, rescue and reconstruction. in Engineering Failure Analysis. 2015;56:360-374.
doi:10.1016/j.engfailanal.2015.01.002 .

Bošnjak, Srđan, Savićević, Sreten, Gnjatović, Nebojša, Milenović, Ivan Lj., Pantelić, Milorad P., "Disaster of the bucket wheel excavator caused by extreme environmental impact: Consequences, rescue and reconstruction" in Engineering Failure Analysis, 56 (2015):360-374,
https://doi.org/10.1016/j.engfailanal.2015.01.002 . .

TY  - JOUR
AU  - Stojadinović, Slavenko
AU  - Tanović, Ljubodrag
AU  - Savićević, Sreten
PY  - 2015
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2131
AB  - The paper contains an experimental study of micro-cutting intended to help the optimization of the grinding process of the silicon nitride ceramic Silinit R (Si3N4 - Al2O3 - AIN - TiN). The investigations were carried out to determine the normal and tangential cutting forces, the critical penetration depth and the specific grinding energy as a function of the grain penetration speed and depth. The micro-cutting process was performed with a single diamond cone-shaped grain (tip angle 120 [degrees] and tip radius 0.2 [min]) at varying depths of cut. The critical grain penetration depth separating ductile flow from brittle fracturing falls within the 6-8 [mu m] range. The specific grinding energy ranges from 135 - 180 [J/mm(3)] in ductile flow and from 60 80 [J/mm(3)] in brittle fracturing.
PB  - Chinese Mechanical Engineering Society
T2  - Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Eng
T1  - Micro-Cutting Mechanisms in Silicon Nitride Ceramics Silinit R Grinding
EP  - 297
IS  - 4
SP  - 291
VL  - 36
UR  - https://hdl.handle.net/21.15107/rcub_machinery_2131
ER  - 

@article{
author = "Stojadinović, Slavenko and Tanović, Ljubodrag and Savićević, Sreten",
year = "2015",
abstract = "The paper contains an experimental study of micro-cutting intended to help the optimization of the grinding process of the silicon nitride ceramic Silinit R (Si3N4 - Al2O3 - AIN - TiN). The investigations were carried out to determine the normal and tangential cutting forces, the critical penetration depth and the specific grinding energy as a function of the grain penetration speed and depth. The micro-cutting process was performed with a single diamond cone-shaped grain (tip angle 120 [degrees] and tip radius 0.2 [min]) at varying depths of cut. The critical grain penetration depth separating ductile flow from brittle fracturing falls within the 6-8 [mu m] range. The specific grinding energy ranges from 135 - 180 [J/mm(3)] in ductile flow and from 60 80 [J/mm(3)] in brittle fracturing.",
publisher = "Chinese Mechanical Engineering Society",
journal = "Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Eng",
title = "Micro-Cutting Mechanisms in Silicon Nitride Ceramics Silinit R Grinding",
pages = "297-291",
number = "4",
volume = "36",
url = "https://hdl.handle.net/21.15107/rcub_machinery_2131"
}

Stojadinović, S., Tanović, L.,& Savićević, S.. (2015). Micro-Cutting Mechanisms in Silicon Nitride Ceramics Silinit R Grinding. in Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Eng
Chinese Mechanical Engineering Society., 36(4), 291-297.
https://hdl.handle.net/21.15107/rcub_machinery_2131

Stojadinović S, Tanović L, Savićević S. Micro-Cutting Mechanisms in Silicon Nitride Ceramics Silinit R Grinding. in Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Eng. 2015;36(4):291-297.
https://hdl.handle.net/21.15107/rcub_machinery_2131 .

Stojadinović, Slavenko, Tanović, Ljubodrag, Savićević, Sreten, "Micro-Cutting Mechanisms in Silicon Nitride Ceramics Silinit R Grinding" in Journal of the Chinese Society of Mechanical Engineers, Transactions of the Chinese Institute of Eng, 36, no. 4 (2015):291-297,
https://hdl.handle.net/21.15107/rcub_machinery_2131 .