TY  - JOUR
AU  - Bošnjak, Srđan
AU  - Zrnić, Nenad
AU  - Momčilović, Dejan
AU  - Gnjatović, Nebojša
AU  - Milenović, Ivan Lj.
PY  - 2020
UR  - http://rims.institutims.rs/handle/123456789/391
AB  - Tie-rods of the bucket wheel and counterweight booms are vital parts of the bucket wheel excavator slewing superstructure. This paper is dedicated to the problem of identifying the stress state of the critical cross-section ('net section') of the eye plates on these tie-rods. It presents the results of the experimental and numerical investigations carried out on the eyebar model. The results show the appearance of a plastic deformation in the zone near the contour of the hole even when the eye is subjected to the loads within the range of the permissible loads prescribed by the standard DIN 22261-2. Plastification in the eye net section occurs across the full thickness of the plate, but it does not jeopardize the integrity of the structure. The stress value in the eye net section, calculated in accordance with the standard DIN 22261-2, is significantly lower than the actual stress values around the hole and serves only as a comparative value for the static strength proof for the eye.
PB  - Elsevier Sci Ltd, Oxford
T2  - Engineering Structures
T1  - Tie-rods of the bucket wheel excavator slewing superstructure: A study of the eye plate stress state
VL  - 207
DO  - 10.1016/j.engstruct.2020.110233
ER  - 

@article{
author = "Bošnjak, Srđan and Zrnić, Nenad and Momčilović, Dejan and Gnjatović, Nebojša and Milenović, Ivan Lj.",
year = "2020",
abstract = "Tie-rods of the bucket wheel and counterweight booms are vital parts of the bucket wheel excavator slewing superstructure. This paper is dedicated to the problem of identifying the stress state of the critical cross-section ('net section') of the eye plates on these tie-rods. It presents the results of the experimental and numerical investigations carried out on the eyebar model. The results show the appearance of a plastic deformation in the zone near the contour of the hole even when the eye is subjected to the loads within the range of the permissible loads prescribed by the standard DIN 22261-2. Plastification in the eye net section occurs across the full thickness of the plate, but it does not jeopardize the integrity of the structure. The stress value in the eye net section, calculated in accordance with the standard DIN 22261-2, is significantly lower than the actual stress values around the hole and serves only as a comparative value for the static strength proof for the eye.",
publisher = "Elsevier Sci Ltd, Oxford",
journal = "Engineering Structures",
title = "Tie-rods of the bucket wheel excavator slewing superstructure: A study of the eye plate stress state",
volume = "207",
doi = "10.1016/j.engstruct.2020.110233"
}

Bošnjak, S., Zrnić, N., Momčilović, D., Gnjatović, N.,& Milenović, I. Lj.. (2020). Tie-rods of the bucket wheel excavator slewing superstructure: A study of the eye plate stress state. in Engineering Structures
Elsevier Sci Ltd, Oxford., 207.
https://doi.org/10.1016/j.engstruct.2020.110233

Bošnjak S, Zrnić N, Momčilović D, Gnjatović N, Milenović IL. Tie-rods of the bucket wheel excavator slewing superstructure: A study of the eye plate stress state. in Engineering Structures. 2020;207.
doi:10.1016/j.engstruct.2020.110233 .

Bošnjak, Srđan, Zrnić, Nenad, Momčilović, Dejan, Gnjatović, Nebojša, Milenović, Ivan Lj., "Tie-rods of the bucket wheel excavator slewing superstructure: A study of the eye plate stress state" in Engineering Structures, 207 (2020),
https://doi.org/10.1016/j.engstruct.2020.110233 . .

TY  - JOUR
AU  - Bošnjak, Srđan
AU  - Zrnić, Nenad
AU  - Momčilović, Dejan
AU  - Gnjatović, Nebojša
AU  - Milenović, Ivan
PY  - 2020
UR  - http://rims.institutims.rs/handle/123456789/451
AB  - An original method for validation of the number of buckets on the working device of a bucket wheel excavator based on the dynamic response of its slewing superstructure (SS) is presented. A set of 16 seemingly acceptable solutions which satisfied the rigid design restrictions, based on the preservation of the existing (a) bucket wheel drivetrain, (b) theoretical capacity, (c) characteristics of the excavated soil and (d) position of the superstructure centre of gravity (CoG), was analysed. Already on the basis of the limiting vertical and lateral accelerations of the bucket wheel centre, which represents a well-grounded indicator of its dynamic behaviour prescribed by the code
DIN 22261-2, 14 out of 16 analysed design variants have been discarded, reducing the set of possible solutions to only two – the originally-designed variant (with 17 buckets), and the variant with 20 buckets. Conclusions on the validity of these two design variants were derived on the basis of the dynamic response analysis of the referent points of the SS. The analysis of the impact of soiling on the dynamic response of the SS has shown that negative dynamic effects, observed in the preceding analysis of the originally-designed solution, increase with the amount
of the adhered material. Although the redesigned variant with 20 buckets has proven as the only suitable solution from the standpoint of dynamic behaviour of the SS, the results have to be assessed carefully due to the fact that the reduction of the mass of the bucket wheel steel structure by more than 14% leads to the appearance of unfavourable dynamic effects, even though the SS CoG position is preserved.
T2  - Engineering Structures
T1  - Bucket wheel excavators_Dynamic response as a criterion for validation of the total number of buckets
VL  - 207
DO  - 10.1016/j.engstruct.2020.110233
ER  - 

@article{
author = "Bošnjak, Srđan and Zrnić, Nenad and Momčilović, Dejan and Gnjatović, Nebojša and Milenović, Ivan",
year = "2020",
abstract = "An original method for validation of the number of buckets on the working device of a bucket wheel excavator based on the dynamic response of its slewing superstructure (SS) is presented. A set of 16 seemingly acceptable solutions which satisfied the rigid design restrictions, based on the preservation of the existing (a) bucket wheel drivetrain, (b) theoretical capacity, (c) characteristics of the excavated soil and (d) position of the superstructure centre of gravity (CoG), was analysed. Already on the basis of the limiting vertical and lateral accelerations of the bucket wheel centre, which represents a well-grounded indicator of its dynamic behaviour prescribed by the code
DIN 22261-2, 14 out of 16 analysed design variants have been discarded, reducing the set of possible solutions to only two – the originally-designed variant (with 17 buckets), and the variant with 20 buckets. Conclusions on the validity of these two design variants were derived on the basis of the dynamic response analysis of the referent points of the SS. The analysis of the impact of soiling on the dynamic response of the SS has shown that negative dynamic effects, observed in the preceding analysis of the originally-designed solution, increase with the amount
of the adhered material. Although the redesigned variant with 20 buckets has proven as the only suitable solution from the standpoint of dynamic behaviour of the SS, the results have to be assessed carefully due to the fact that the reduction of the mass of the bucket wheel steel structure by more than 14% leads to the appearance of unfavourable dynamic effects, even though the SS CoG position is preserved.",
journal = "Engineering Structures",
title = "Bucket wheel excavators_Dynamic response as a criterion for validation of the total number of buckets",
volume = "207",
doi = "10.1016/j.engstruct.2020.110233"
}

Bošnjak, S., Zrnić, N., Momčilović, D., Gnjatović, N.,& Milenović, I.. (2020). Bucket wheel excavators_Dynamic response as a criterion for validation of the total number of buckets. in Engineering Structures, 207.
https://doi.org/10.1016/j.engstruct.2020.110233

Bošnjak S, Zrnić N, Momčilović D, Gnjatović N, Milenović I. Bucket wheel excavators_Dynamic response as a criterion for validation of the total number of buckets. in Engineering Structures. 2020;207.
doi:10.1016/j.engstruct.2020.110233 .

Bošnjak, Srđan, Zrnić, Nenad, Momčilović, Dejan, Gnjatović, Nebojša, Milenović, Ivan, "Bucket wheel excavators_Dynamic response as a criterion for validation of the total number of buckets" in Engineering Structures, 207 (2020),
https://doi.org/10.1016/j.engstruct.2020.110233 . .

TY  - JOUR
AU  - Arsić, Miodrag
AU  - Bošnjak, Srđan
AU  - Sedmak, Simon
AU  - Vistać, Brane
AU  - Savić, Zoran
PY  - 2019
UR  - http://rims.institutims.rs/handle/123456789/361
AB  - During the revitalization of the hydroelectric generating station A4 at the hydro power plant 'Djerdap 1', all of its parts are subjected to non-destructive testing. Cracks are detected in cast part of generator rotor hub, in the flange area toward the turbine shaft. Cracks were 10-500 mm long (determined by magnetic particle tests) and 60-100 mm deep (ultrasonic tests). The generator rotor hub is made of cast steel 25L, in accordance with the standard 977-75. The welding/surface welding repair technology in the detected crack zones of the cast part of generator rotor hub includes a large number of details, due to the structural solution and generator rotor function in service. It was also necessary to provide the carefully undertaken activities in order to enable safe operation and continuous use of the rotor hub. Failing to notice, underestimation or incorrect perception of important details could cause significant problems in hydroelectric generating station operation. The paper, due to specifics of reparation technology, contains arranged preparatory activities for the procedure apart from the welding/surface welding technology. It is of importance to mention a huge amount of money savings, The manufacture of a new generator rotor would cost over 4 million EUR (generator mass is over 300 tonnes), not taking into account the time needed for its making (6-12 months), which is directly related to the amount of energy a hydroelectric generating station can produce during that period. This technology of repair welding is also applicable for other components and structures of the turbine and the hydromechanical equipment subjected to various causes of damage during exploitation.
PB  - Institut za ispitivanje materijala, Beograd
T2  - Structural Integrity and Life
T1  - Repair of cracks detected in cast components of vertical Kaplan turbine rotor hub
EP  - 250
IS  - 3
SP  - 243
VL  - 19
UR  - https://hdl.handle.net/21.15107/rcub_rims_361
ER  - 

@article{
author = "Arsić, Miodrag and Bošnjak, Srđan and Sedmak, Simon and Vistać, Brane and Savić, Zoran",
year = "2019",
abstract = "During the revitalization of the hydroelectric generating station A4 at the hydro power plant 'Djerdap 1', all of its parts are subjected to non-destructive testing. Cracks are detected in cast part of generator rotor hub, in the flange area toward the turbine shaft. Cracks were 10-500 mm long (determined by magnetic particle tests) and 60-100 mm deep (ultrasonic tests). The generator rotor hub is made of cast steel 25L, in accordance with the standard 977-75. The welding/surface welding repair technology in the detected crack zones of the cast part of generator rotor hub includes a large number of details, due to the structural solution and generator rotor function in service. It was also necessary to provide the carefully undertaken activities in order to enable safe operation and continuous use of the rotor hub. Failing to notice, underestimation or incorrect perception of important details could cause significant problems in hydroelectric generating station operation. The paper, due to specifics of reparation technology, contains arranged preparatory activities for the procedure apart from the welding/surface welding technology. It is of importance to mention a huge amount of money savings, The manufacture of a new generator rotor would cost over 4 million EUR (generator mass is over 300 tonnes), not taking into account the time needed for its making (6-12 months), which is directly related to the amount of energy a hydroelectric generating station can produce during that period. This technology of repair welding is also applicable for other components and structures of the turbine and the hydromechanical equipment subjected to various causes of damage during exploitation.",
publisher = "Institut za ispitivanje materijala, Beograd",
journal = "Structural Integrity and Life",
title = "Repair of cracks detected in cast components of vertical Kaplan turbine rotor hub",
pages = "250-243",
number = "3",
volume = "19",
url = "https://hdl.handle.net/21.15107/rcub_rims_361"
}

Arsić, M., Bošnjak, S., Sedmak, S., Vistać, B.,& Savić, Z.. (2019). Repair of cracks detected in cast components of vertical Kaplan turbine rotor hub. in Structural Integrity and Life
Institut za ispitivanje materijala, Beograd., 19(3), 243-250.
https://hdl.handle.net/21.15107/rcub_rims_361

Arsić M, Bošnjak S, Sedmak S, Vistać B, Savić Z. Repair of cracks detected in cast components of vertical Kaplan turbine rotor hub. in Structural Integrity and Life. 2019;19(3):243-250.
https://hdl.handle.net/21.15107/rcub_rims_361 .

Arsić, Miodrag, Bošnjak, Srđan, Sedmak, Simon, Vistać, Brane, Savić, Zoran, "Repair of cracks detected in cast components of vertical Kaplan turbine rotor hub" in Structural Integrity and Life, 19, no. 3 (2019):243-250,
https://hdl.handle.net/21.15107/rcub_rims_361 .

TY  - CONF
AU  - Arsić, Miodrag
AU  - Bošnjak, Srđan
AU  - Gnjatović, Nebojša
AU  - Sedmak, Simon
AU  - Arsić, D.
AU  - Savić, Zoran
PY  - 2018
UR  - http://rims.institutims.rs/handle/123456789/334
AB  - This paper presents a methodological approach for the assessment of service life of vital welded structures of a bucket-wheel excavator Sch Rs 650/5x24 ('Thyssen Krupp', Germany) boom, subjected to cyclic loading with a variable amplitude through the use of experimental tests carried out in order to determine operational strength and growth of a fatigue crack. Realized researches and results presented in this paper offer great possibilities for the analyses of behaviour of vital welded structures of the bucket-wheel boom. By the application of the measurement device with 8 channels for registration and processing of electric signals HBM Spider 8 and measurement tapes HBM 6/350xXY31 deformations were measured at vital welded structures of the boom in the area of the bucket-wheel, made of steels St 37.2 and St 52.3 in accordance with standard DIN 17100, or steels S235J2G3 and S355J2G3 in accordance with standard EN 10025-2. The objective of the test is to determine if there is a possibility of occurrence of plastic deformations or initial cracks due to fatigue at vital welded structures. Tests that refer to the growth of the fatigue crack located at the welded joint have been carried out by bending at three points with asymmetric load R = 0.5 (R = sigma(min) / sigma(max)) at the specimen with a single edge notch. Tests were performed through the use of controlled force, ranging between F-max and F-min at the high frequency pulsator 'Cracktronic', while obtainment of data regarding the crack growth was carried out through the use of measurement gauge ARM A-10.
PB  - Elsevier Science Bv, Amsterdam
C3  - ECF22 - Loading and Environmental Effects on Structural Integrity
T1  - Determination of Residual Fatigue Life of Welded Structures at Bucket-Wheel Excavators through the Use of Fracture Mechanics
EP  - 84
SP  - 79
VL  - 13
DO  - 10.1016/j.prostr.2018.12.014
ER  - 

@conference{
author = "Arsić, Miodrag and Bošnjak, Srđan and Gnjatović, Nebojša and Sedmak, Simon and Arsić, D. and Savić, Zoran",
year = "2018",
abstract = "This paper presents a methodological approach for the assessment of service life of vital welded structures of a bucket-wheel excavator Sch Rs 650/5x24 ('Thyssen Krupp', Germany) boom, subjected to cyclic loading with a variable amplitude through the use of experimental tests carried out in order to determine operational strength and growth of a fatigue crack. Realized researches and results presented in this paper offer great possibilities for the analyses of behaviour of vital welded structures of the bucket-wheel boom. By the application of the measurement device with 8 channels for registration and processing of electric signals HBM Spider 8 and measurement tapes HBM 6/350xXY31 deformations were measured at vital welded structures of the boom in the area of the bucket-wheel, made of steels St 37.2 and St 52.3 in accordance with standard DIN 17100, or steels S235J2G3 and S355J2G3 in accordance with standard EN 10025-2. The objective of the test is to determine if there is a possibility of occurrence of plastic deformations or initial cracks due to fatigue at vital welded structures. Tests that refer to the growth of the fatigue crack located at the welded joint have been carried out by bending at three points with asymmetric load R = 0.5 (R = sigma(min) / sigma(max)) at the specimen with a single edge notch. Tests were performed through the use of controlled force, ranging between F-max and F-min at the high frequency pulsator 'Cracktronic', while obtainment of data regarding the crack growth was carried out through the use of measurement gauge ARM A-10.",
publisher = "Elsevier Science Bv, Amsterdam",
journal = "ECF22 - Loading and Environmental Effects on Structural Integrity",
title = "Determination of Residual Fatigue Life of Welded Structures at Bucket-Wheel Excavators through the Use of Fracture Mechanics",
pages = "84-79",
volume = "13",
doi = "10.1016/j.prostr.2018.12.014"
}

Arsić, M., Bošnjak, S., Gnjatović, N., Sedmak, S., Arsić, D.,& Savić, Z.. (2018). Determination of Residual Fatigue Life of Welded Structures at Bucket-Wheel Excavators through the Use of Fracture Mechanics. in ECF22 - Loading and Environmental Effects on Structural Integrity
Elsevier Science Bv, Amsterdam., 13, 79-84.
https://doi.org/10.1016/j.prostr.2018.12.014

Arsić M, Bošnjak S, Gnjatović N, Sedmak S, Arsić D, Savić Z. Determination of Residual Fatigue Life of Welded Structures at Bucket-Wheel Excavators through the Use of Fracture Mechanics. in ECF22 - Loading and Environmental Effects on Structural Integrity. 2018;13:79-84.
doi:10.1016/j.prostr.2018.12.014 .

Arsić, Miodrag, Bošnjak, Srđan, Gnjatović, Nebojša, Sedmak, Simon, Arsić, D., Savić, Zoran, "Determination of Residual Fatigue Life of Welded Structures at Bucket-Wheel Excavators through the Use of Fracture Mechanics" in ECF22 - Loading and Environmental Effects on Structural Integrity, 13 (2018):79-84,
https://doi.org/10.1016/j.prostr.2018.12.014 . .

TY  - JOUR
AU  - Sedmak, Aleksandar
AU  - Bošnjak, Srđan
AU  - Arsić, Miodrag
AU  - Sedmak, S.A.
AU  - Savić, Zoran
PY  - 2016
UR  - http://rims.institutims.rs/handle/123456789/304
AB  - This paper presents integrity and life estimation of turbine runner cover in a vertical pipe turbines, Kaplan 200 MW nominal output power, produced in Russia, and built in six hydro-generation units of hydroelectric power plant „Đerdap 1” in Serbia. Fatigue and corrosion-fatigue interaction have been taken into account using experimentally obtained material properties, as well as analytical and numerical calculations of stress state, to estimate appropriate safety factors. Fatigue crack growth rate, da/dN, was also calculated, indicated that internal defects of circular or elliptical shape, found out by ultrasonic testing, do not affect reliable operation of runner cover.
PB  - Gruppo Italiano Frattura
T2  - Frattura ed Integrita Strutturale
T1  - Integrity and life estimation of turbine runner cover in a hydro power plant
EP  - 68
IS  - 36
SP  - 63
VL  - 10
DO  - 10.3221/IGF-ESIS.36.07
ER  - 

@article{
author = "Sedmak, Aleksandar and Bošnjak, Srđan and Arsić, Miodrag and Sedmak, S.A. and Savić, Zoran",
year = "2016",
abstract = "This paper presents integrity and life estimation of turbine runner cover in a vertical pipe turbines, Kaplan 200 MW nominal output power, produced in Russia, and built in six hydro-generation units of hydroelectric power plant „Đerdap 1” in Serbia. Fatigue and corrosion-fatigue interaction have been taken into account using experimentally obtained material properties, as well as analytical and numerical calculations of stress state, to estimate appropriate safety factors. Fatigue crack growth rate, da/dN, was also calculated, indicated that internal defects of circular or elliptical shape, found out by ultrasonic testing, do not affect reliable operation of runner cover.",
publisher = "Gruppo Italiano Frattura",
journal = "Frattura ed Integrita Strutturale",
title = "Integrity and life estimation of turbine runner cover in a hydro power plant",
pages = "68-63",
number = "36",
volume = "10",
doi = "10.3221/IGF-ESIS.36.07"
}

Sedmak, A., Bošnjak, S., Arsić, M., Sedmak, S.A.,& Savić, Z.. (2016). Integrity and life estimation of turbine runner cover in a hydro power plant. in Frattura ed Integrita Strutturale
Gruppo Italiano Frattura., 10(36), 63-68.
https://doi.org/10.3221/IGF-ESIS.36.07

Sedmak A, Bošnjak S, Arsić M, Sedmak S, Savić Z. Integrity and life estimation of turbine runner cover in a hydro power plant. in Frattura ed Integrita Strutturale. 2016;10(36):63-68.
doi:10.3221/IGF-ESIS.36.07 .

Sedmak, Aleksandar, Bošnjak, Srđan, Arsić, Miodrag, Sedmak, S.A., Savić, Zoran, "Integrity and life estimation of turbine runner cover in a hydro power plant" in Frattura ed Integrita Strutturale, 10, no. 36 (2016):63-68,
https://doi.org/10.3221/IGF-ESIS.36.07 . .

TY  - JOUR
AU  - Arsić, Miodrag
AU  - Bošnjak, Srđan
AU  - Sedmak, Simon
AU  - Šarkočević, Živče
AU  - Savić, Zoran
AU  - Radu, D.
PY  - 2016
UR  - http://rims.institutims.rs/handle/123456789/298
AB  - Results of non-destructive testing of the Kaplan turbine runner manhole welded structure are presented, on the basis of which the repair methodology is defined. During repair, the welding technology for elements of the manhole is modified along with the proposal given for the modification of its structural design, because the finite element method calculation proved that the rectangular welded structure of the manhole was significantly better than round welded structure when it comes to integrity and service life.
PB  - Institut za ispitivanje materijala, Beograd
T2  - Structural Integrity and Life
T1  - Determination of damage and repair methodology for the runner manhole of Kaplan turbine at the hydro power plant 'Djerdap 1'
EP  - 153
IS  - 3
SP  - 149
VL  - 16
UR  - https://hdl.handle.net/21.15107/rcub_rims_298
ER  - 

@article{
author = "Arsić, Miodrag and Bošnjak, Srđan and Sedmak, Simon and Šarkočević, Živče and Savić, Zoran and Radu, D.",
year = "2016",
abstract = "Results of non-destructive testing of the Kaplan turbine runner manhole welded structure are presented, on the basis of which the repair methodology is defined. During repair, the welding technology for elements of the manhole is modified along with the proposal given for the modification of its structural design, because the finite element method calculation proved that the rectangular welded structure of the manhole was significantly better than round welded structure when it comes to integrity and service life.",
publisher = "Institut za ispitivanje materijala, Beograd",
journal = "Structural Integrity and Life",
title = "Determination of damage and repair methodology for the runner manhole of Kaplan turbine at the hydro power plant 'Djerdap 1'",
pages = "153-149",
number = "3",
volume = "16",
url = "https://hdl.handle.net/21.15107/rcub_rims_298"
}

Arsić, M., Bošnjak, S., Sedmak, S., Šarkočević, Ž., Savić, Z.,& Radu, D.. (2016). Determination of damage and repair methodology for the runner manhole of Kaplan turbine at the hydro power plant 'Djerdap 1'. in Structural Integrity and Life
Institut za ispitivanje materijala, Beograd., 16(3), 149-153.
https://hdl.handle.net/21.15107/rcub_rims_298

Arsić M, Bošnjak S, Sedmak S, Šarkočević Ž, Savić Z, Radu D. Determination of damage and repair methodology for the runner manhole of Kaplan turbine at the hydro power plant 'Djerdap 1'. in Structural Integrity and Life. 2016;16(3):149-153.
https://hdl.handle.net/21.15107/rcub_rims_298 .

Arsić, Miodrag, Bošnjak, Srđan, Sedmak, Simon, Šarkočević, Živče, Savić, Zoran, Radu, D., "Determination of damage and repair methodology for the runner manhole of Kaplan turbine at the hydro power plant 'Djerdap 1'" in Structural Integrity and Life, 16, no. 3 (2016):149-153,
https://hdl.handle.net/21.15107/rcub_rims_298 .

TY  - JOUR
AU  - Arsić, Miodrag
AU  - Savić, Zoran
AU  - Sedmak, Aleksandar
AU  - Bošnjak, Srđan
AU  - Sedmak, Simon
PY  - 2016
UR  - http://rims.institutims.rs/handle/123456789/296
AB  - This paper presents results of experimental examinations of stress concentration influence to fatigue life of butt welded joints with K-groove, produced from the most frequently used structural steel S355J2+N. One group of experiments comprised examinations carried out on the K-groove specimens with stress concentrators of edged notch type. Specimens with short cracks (limited length of initial crack), defined on the basis of the experience from fracture mechanics by the three points bending examinations, have been examined according to standard for the determination of S-N curve, and aimed to determine fatigue strengths for different lengths of initial crack and Relationship between fatigue strength and crack length. Other group of experiments comprised examinations of specimens with edge notch, prepared in accordance with ASTM E 399 for three points bending, in order to establish regularity between crack growth and range of exerted stress intensity factor aimed to determine resistance of welded joint to initial crack growth, namely fatigue threshold (ΔKth).
PB  - Gruppo Italiano Frattura
T2  - Frattura ed Integrita Strutturale
T1  - Experimental examination of fatigue life of welded joint with stress concentration
EP  - 35
IS  - 36
SP  - 27
VL  - 10
DO  - 10.3221/IGF-ESIS.36.03
ER  - 

@article{
author = "Arsić, Miodrag and Savić, Zoran and Sedmak, Aleksandar and Bošnjak, Srđan and Sedmak, Simon",
year = "2016",
abstract = "This paper presents results of experimental examinations of stress concentration influence to fatigue life of butt welded joints with K-groove, produced from the most frequently used structural steel S355J2+N. One group of experiments comprised examinations carried out on the K-groove specimens with stress concentrators of edged notch type. Specimens with short cracks (limited length of initial crack), defined on the basis of the experience from fracture mechanics by the three points bending examinations, have been examined according to standard for the determination of S-N curve, and aimed to determine fatigue strengths for different lengths of initial crack and Relationship between fatigue strength and crack length. Other group of experiments comprised examinations of specimens with edge notch, prepared in accordance with ASTM E 399 for three points bending, in order to establish regularity between crack growth and range of exerted stress intensity factor aimed to determine resistance of welded joint to initial crack growth, namely fatigue threshold (ΔKth).",
publisher = "Gruppo Italiano Frattura",
journal = "Frattura ed Integrita Strutturale",
title = "Experimental examination of fatigue life of welded joint with stress concentration",
pages = "35-27",
number = "36",
volume = "10",
doi = "10.3221/IGF-ESIS.36.03"
}

Arsić, M., Savić, Z., Sedmak, A., Bošnjak, S.,& Sedmak, S.. (2016). Experimental examination of fatigue life of welded joint with stress concentration. in Frattura ed Integrita Strutturale
Gruppo Italiano Frattura., 10(36), 27-35.
https://doi.org/10.3221/IGF-ESIS.36.03

Arsić M, Savić Z, Sedmak A, Bošnjak S, Sedmak S. Experimental examination of fatigue life of welded joint with stress concentration. in Frattura ed Integrita Strutturale. 2016;10(36):27-35.
doi:10.3221/IGF-ESIS.36.03 .

Arsić, Miodrag, Savić, Zoran, Sedmak, Aleksandar, Bošnjak, Srđan, Sedmak, Simon, "Experimental examination of fatigue life of welded joint with stress concentration" in Frattura ed Integrita Strutturale, 10, no. 36 (2016):27-35,
https://doi.org/10.3221/IGF-ESIS.36.03 . .

TY  - JOUR
AU  - Sedmak, Simon
AU  - Arsić, Miodrag
AU  - Bošnjak, Srđan
AU  - Malešević, Zoranka
AU  - Savić, Zoran
AU  - Radu, D.
PY  - 2016
UR  - http://rims.institutims.rs/handle/123456789/288
AB  - This paper presents the integrity and reliability evaluation of the heating system as a whole, based on results of metallographic tests performed on parent material and the ultrasonic measurement of wall thickness of elbows made of steel St 35.8.
PB  - Institut za ispitivanje materijala, Beograd
T2  - Structural Integrity and Life
T1  - Effect of locally damaged elbow segments on the integrity and reliability of the heating system
EP  - 170
IS  - 3
SP  - 167
VL  - 16
UR  - https://hdl.handle.net/21.15107/rcub_rims_288
ER  - 

@article{
author = "Sedmak, Simon and Arsić, Miodrag and Bošnjak, Srđan and Malešević, Zoranka and Savić, Zoran and Radu, D.",
year = "2016",
abstract = "This paper presents the integrity and reliability evaluation of the heating system as a whole, based on results of metallographic tests performed on parent material and the ultrasonic measurement of wall thickness of elbows made of steel St 35.8.",
publisher = "Institut za ispitivanje materijala, Beograd",
journal = "Structural Integrity and Life",
title = "Effect of locally damaged elbow segments on the integrity and reliability of the heating system",
pages = "170-167",
number = "3",
volume = "16",
url = "https://hdl.handle.net/21.15107/rcub_rims_288"
}

Sedmak, S., Arsić, M., Bošnjak, S., Malešević, Z., Savić, Z.,& Radu, D.. (2016). Effect of locally damaged elbow segments on the integrity and reliability of the heating system. in Structural Integrity and Life
Institut za ispitivanje materijala, Beograd., 16(3), 167-170.
https://hdl.handle.net/21.15107/rcub_rims_288

Sedmak S, Arsić M, Bošnjak S, Malešević Z, Savić Z, Radu D. Effect of locally damaged elbow segments on the integrity and reliability of the heating system. in Structural Integrity and Life. 2016;16(3):167-170.
https://hdl.handle.net/21.15107/rcub_rims_288 .

Sedmak, Simon, Arsić, Miodrag, Bošnjak, Srđan, Malešević, Zoranka, Savić, Zoran, Radu, D., "Effect of locally damaged elbow segments on the integrity and reliability of the heating system" in Structural Integrity and Life, 16, no. 3 (2016):167-170,
https://hdl.handle.net/21.15107/rcub_rims_288 .

TY  - JOUR
AU  - Bošnjak, Srđan
AU  - Gnjatović, Nebojša
AU  - Momčilović, Dejan
AU  - Milenović, Ivan Lj.
AU  - Gašić, V.M.
PY  - 2015
UR  - http://rims.institutims.rs/handle/123456789/276
AB  - This paper presents an investigation of the accident which occurred during startup of the extending structure from the transport position. In order to clarify the causes of crack occurrence along almost the entire surface of the lever cross-section, the authors performed visual, experimental (chemical composition, tensile properties, microhardness) as well as metallographic examinations. Stress states in the critical zone are defined by applying the finite element method (FEM). Based on the investigation results it was concluded that the lever breakdown is predominantly caused by both the 'operating-in' defect (the malfunction of the limit switch) and the 'manufacturing-in' defect (poor weld quality). The investigation results presented in this paper are important because same or similar problems could arise in supporting structures of various types of transportation, construction and mining machines.
PB  - Elsevier Ltd
T2  - Case Studies in Engineering Failure Analysis
T1  - Failure analysis of the mobile elevating work platform
EP  - 87
SP  - 80
VL  - 3
DO  - 10.1016/j.csefa.2015.03.005
ER  - 

@article{
author = "Bošnjak, Srđan and Gnjatović, Nebojša and Momčilović, Dejan and Milenović, Ivan Lj. and Gašić, V.M.",
year = "2015",
abstract = "This paper presents an investigation of the accident which occurred during startup of the extending structure from the transport position. In order to clarify the causes of crack occurrence along almost the entire surface of the lever cross-section, the authors performed visual, experimental (chemical composition, tensile properties, microhardness) as well as metallographic examinations. Stress states in the critical zone are defined by applying the finite element method (FEM). Based on the investigation results it was concluded that the lever breakdown is predominantly caused by both the 'operating-in' defect (the malfunction of the limit switch) and the 'manufacturing-in' defect (poor weld quality). The investigation results presented in this paper are important because same or similar problems could arise in supporting structures of various types of transportation, construction and mining machines.",
publisher = "Elsevier Ltd",
journal = "Case Studies in Engineering Failure Analysis",
title = "Failure analysis of the mobile elevating work platform",
pages = "87-80",
volume = "3",
doi = "10.1016/j.csefa.2015.03.005"
}

Bošnjak, S., Gnjatović, N., Momčilović, D., Milenović, I. Lj.,& Gašić, V.M.. (2015). Failure analysis of the mobile elevating work platform. in Case Studies in Engineering Failure Analysis
Elsevier Ltd., 3, 80-87.
https://doi.org/10.1016/j.csefa.2015.03.005

Bošnjak S, Gnjatović N, Momčilović D, Milenović IL, Gašić V. Failure analysis of the mobile elevating work platform. in Case Studies in Engineering Failure Analysis. 2015;3:80-87.
doi:10.1016/j.csefa.2015.03.005 .

Bošnjak, Srđan, Gnjatović, Nebojša, Momčilović, Dejan, Milenović, Ivan Lj., Gašić, V.M., "Failure analysis of the mobile elevating work platform" in Case Studies in Engineering Failure Analysis, 3 (2015):80-87,
https://doi.org/10.1016/j.csefa.2015.03.005 . .

TY  - CONF
AU  - Arsić, Miodrag
AU  - Vistać, Brane
AU  - Bošnjak, Srđan
AU  - Grabulov, Vencislav
AU  - Savić, Zoran
PY  - 2014
UR  - http://rims.institutims.rs/handle/123456789/248
AB  - Vertical Kaplan turbines, manufactured in Russia and with nominal power of 200 MW, have been installed in 6 hydroelectric generating units at ’Djerdap 1’. During the refurbishment of hydropower plant experimental non-destructive tests were performed in order to determine the state of turbine components. During the course of testing damage was detected at sleeves and welded shields of guide vanes, which occurred as a consequence of turbine shaft vibrations. 1782 mm long guide vane sleeves were made of cast steel 25L (GOST standard), 260 mm long sleeve was made of forged steel St 25 (GOST standard), while welded shields of guide vanes were made of austenitic steel 08X18H10T (GOST standard). Results of experimental tests and methodology for reparation of damaged surfaces of sleeves and welded shields of guide vanes are presented in this paper. It was necessary, due to the structural solution used for the design of guide vanes and their function during service, to define a large number of details, carefully reconsider them and carry out all activities with extreme care in order to enable the safe operation and continuous use of vanes through the use of reparation methodology for welding/surface welding of sleeves and welded shields. Overlooking, underestimation or incorrect perception of important details could cause significant problems during turbine operation.
PB  - Trans Tech Publications Ltd
C3  - Advanced Materials Research
T1  - Methodology for reparation of damaged sleeves and welded shield sections of guide vanes at hydropower plant DJERDAP 1
EP  - 13
SP  - 8
VL  - 1029
DO  - 10.4028/www.scientific.net/AMR.1029.8
ER  - 

@conference{
author = "Arsić, Miodrag and Vistać, Brane and Bošnjak, Srđan and Grabulov, Vencislav and Savić, Zoran",
year = "2014",
abstract = "Vertical Kaplan turbines, manufactured in Russia and with nominal power of 200 MW, have been installed in 6 hydroelectric generating units at ’Djerdap 1’. During the refurbishment of hydropower plant experimental non-destructive tests were performed in order to determine the state of turbine components. During the course of testing damage was detected at sleeves and welded shields of guide vanes, which occurred as a consequence of turbine shaft vibrations. 1782 mm long guide vane sleeves were made of cast steel 25L (GOST standard), 260 mm long sleeve was made of forged steel St 25 (GOST standard), while welded shields of guide vanes were made of austenitic steel 08X18H10T (GOST standard). Results of experimental tests and methodology for reparation of damaged surfaces of sleeves and welded shields of guide vanes are presented in this paper. It was necessary, due to the structural solution used for the design of guide vanes and their function during service, to define a large number of details, carefully reconsider them and carry out all activities with extreme care in order to enable the safe operation and continuous use of vanes through the use of reparation methodology for welding/surface welding of sleeves and welded shields. Overlooking, underestimation or incorrect perception of important details could cause significant problems during turbine operation.",
publisher = "Trans Tech Publications Ltd",
journal = "Advanced Materials Research",
title = "Methodology for reparation of damaged sleeves and welded shield sections of guide vanes at hydropower plant DJERDAP 1",
pages = "13-8",
volume = "1029",
doi = "10.4028/www.scientific.net/AMR.1029.8"
}

Arsić, M., Vistać, B., Bošnjak, S., Grabulov, V.,& Savić, Z.. (2014). Methodology for reparation of damaged sleeves and welded shield sections of guide vanes at hydropower plant DJERDAP 1. in Advanced Materials Research
Trans Tech Publications Ltd., 1029, 8-13.
https://doi.org/10.4028/www.scientific.net/AMR.1029.8

Arsić M, Vistać B, Bošnjak S, Grabulov V, Savić Z. Methodology for reparation of damaged sleeves and welded shield sections of guide vanes at hydropower plant DJERDAP 1. in Advanced Materials Research. 2014;1029:8-13.
doi:10.4028/www.scientific.net/AMR.1029.8 .

Arsić, Miodrag, Vistać, Brane, Bošnjak, Srđan, Grabulov, Vencislav, Savić, Zoran, "Methodology for reparation of damaged sleeves and welded shield sections of guide vanes at hydropower plant DJERDAP 1" in Advanced Materials Research, 1029 (2014):8-13,
https://doi.org/10.4028/www.scientific.net/AMR.1029.8 . .

TY  - CONF
AU  - Arsić, Miodrag
AU  - Bošnjak, Srđan
AU  - Grabulov, Vencislav
AU  - Veljović, Aleksandar
AU  - Savić, Zoran
PY  - 2014
UR  - http://rims.institutims.rs/handle/123456789/238
AB  - Stable supply tank, with volume V = 250 m3 and operating pressure p = 1,5 MPa, of generation unit 6 at thermal power plant 'Nikola Tesla A' in Obrenovac, is designed for water-steam working fluid. It was made of steel Č 1204 as a single-part welded structure with a single wall. Cylindrical tank shell consists of 8 segments, while torispherical deep bottoms consist of 3 segments. The tank is in the horizontal position and it lays on 4 supports. There are five manometers installed at the tank for pressure control, as well as 5 spring-loaded safety valves. In this paper results of non-destructive tests performed on the tank are presented. Mechanical damages on parent material, up to 1.5 mm deep, were detected at the outer surface of the cylindrical section of the right bottom (as seen from the boiler) and on the inner surface of the shell, as well as sporadic pitting corrosion, up to 0.5 mm deep, and 2 mm misalignment of sheet metals in areas where shell segments are joined. Crack type linear indications were detected on the surface of welded joints through the use of magnetic particle testing. Through ultrasonic and radiographic testing it was determined that the homogeneity of welded joints is satisfactory. Hardness testing was performed on all segments of the tank, and obtained values were in the range between 118 and 130 HB. Metallographic examination, performed on specimens of all segments of the tank, showed that microstructure of material is either fine-grained or striped ferrite-pearlite. On the basis of test results the repair technology for shell and bottom segments was made, while on the basis of the analytical calculation of tank strength the integrity evaluation was carried out for the upcoming period of service, depending on the category of the vessel.
PB  - Trans Tech Publications Ltd
C3  - Advanced Materials Research
T1  - Analysis of current state and integrity evaluation for the supply tank of generation unit 6 of thermal power plant Nikola Tesla ”A”, Obrenovac
EP  - 19
SP  - 14
VL  - 1029
DO  - 10.4028/www.scientific.net/AMR.1029.14
ER  - 

@conference{
author = "Arsić, Miodrag and Bošnjak, Srđan and Grabulov, Vencislav and Veljović, Aleksandar and Savić, Zoran",
year = "2014",
abstract = "Stable supply tank, with volume V = 250 m3 and operating pressure p = 1,5 MPa, of generation unit 6 at thermal power plant 'Nikola Tesla A' in Obrenovac, is designed for water-steam working fluid. It was made of steel Č 1204 as a single-part welded structure with a single wall. Cylindrical tank shell consists of 8 segments, while torispherical deep bottoms consist of 3 segments. The tank is in the horizontal position and it lays on 4 supports. There are five manometers installed at the tank for pressure control, as well as 5 spring-loaded safety valves. In this paper results of non-destructive tests performed on the tank are presented. Mechanical damages on parent material, up to 1.5 mm deep, were detected at the outer surface of the cylindrical section of the right bottom (as seen from the boiler) and on the inner surface of the shell, as well as sporadic pitting corrosion, up to 0.5 mm deep, and 2 mm misalignment of sheet metals in areas where shell segments are joined. Crack type linear indications were detected on the surface of welded joints through the use of magnetic particle testing. Through ultrasonic and radiographic testing it was determined that the homogeneity of welded joints is satisfactory. Hardness testing was performed on all segments of the tank, and obtained values were in the range between 118 and 130 HB. Metallographic examination, performed on specimens of all segments of the tank, showed that microstructure of material is either fine-grained or striped ferrite-pearlite. On the basis of test results the repair technology for shell and bottom segments was made, while on the basis of the analytical calculation of tank strength the integrity evaluation was carried out for the upcoming period of service, depending on the category of the vessel.",
publisher = "Trans Tech Publications Ltd",
journal = "Advanced Materials Research",
title = "Analysis of current state and integrity evaluation for the supply tank of generation unit 6 of thermal power plant Nikola Tesla ”A”, Obrenovac",
pages = "19-14",
volume = "1029",
doi = "10.4028/www.scientific.net/AMR.1029.14"
}

Arsić, M., Bošnjak, S., Grabulov, V., Veljović, A.,& Savić, Z.. (2014). Analysis of current state and integrity evaluation for the supply tank of generation unit 6 of thermal power plant Nikola Tesla ”A”, Obrenovac. in Advanced Materials Research
Trans Tech Publications Ltd., 1029, 14-19.
https://doi.org/10.4028/www.scientific.net/AMR.1029.14

Arsić M, Bošnjak S, Grabulov V, Veljović A, Savić Z. Analysis of current state and integrity evaluation for the supply tank of generation unit 6 of thermal power plant Nikola Tesla ”A”, Obrenovac. in Advanced Materials Research. 2014;1029:14-19.
doi:10.4028/www.scientific.net/AMR.1029.14 .

Arsić, Miodrag, Bošnjak, Srđan, Grabulov, Vencislav, Veljović, Aleksandar, Savić, Zoran, "Analysis of current state and integrity evaluation for the supply tank of generation unit 6 of thermal power plant Nikola Tesla ”A”, Obrenovac" in Advanced Materials Research, 1029 (2014):14-19,
https://doi.org/10.4028/www.scientific.net/AMR.1029.14 . .

TY  - JOUR
AU  - Arsić, Miodrag
AU  - Vistać, Brane
AU  - Bošnjak, Srđan
AU  - Bošković, Goran
AU  - Savić, Zoran
PY  - 2014
UR  - http://rims.institutims.rs/handle/123456789/245
AB  - Turbine and hydromechanical equipment at hydro power plant 'Đerdap 1' is subjected to service conditions which lead to degradation of materials and structures. Taking into account the frequency of failure occurrence and experience accumulated through long term testing and determination of state, it can be concluded that basic causes of equipment degradation are: oscillations, fatigue, corrosion, erosion and cavitation. It is the responsibility of manufacturers of turbine and hydromechanical equipment to make sure that all vital parts and supporting structures are made in compliance with technical requirements, suitable standards and european directives that refer to structural integrity. Applicability of Pressure Equipment Directive 97/23/EC and Machinery Directive 98/37/EEC is especially relevant, due to the fact that certain parts and structures of turbine regulation system, lubrication system, turbine runner and measurement system are subject to one of the above mentioned directives. This paper contains the overview and basic parameters of new and general approach to standardization and technical harmonization of hydro power plant equipment that refers to structural integrity.
PB  - Institut IMK "14. oktobar", Kruševac
T2  - IMK-14 - Istraživanje i razvoj
T1  - Guidelines for technical regulations and standardization of turbine and hydromechanical equipment during production and exploitation
EP  - 7
IS  - 1
SP  - 1
VL  - 20
DO  - 10.5937/IMK1401001A
ER  - 

@article{
author = "Arsić, Miodrag and Vistać, Brane and Bošnjak, Srđan and Bošković, Goran and Savić, Zoran",
year = "2014",
abstract = "Turbine and hydromechanical equipment at hydro power plant 'Đerdap 1' is subjected to service conditions which lead to degradation of materials and structures. Taking into account the frequency of failure occurrence and experience accumulated through long term testing and determination of state, it can be concluded that basic causes of equipment degradation are: oscillations, fatigue, corrosion, erosion and cavitation. It is the responsibility of manufacturers of turbine and hydromechanical equipment to make sure that all vital parts and supporting structures are made in compliance with technical requirements, suitable standards and european directives that refer to structural integrity. Applicability of Pressure Equipment Directive 97/23/EC and Machinery Directive 98/37/EEC is especially relevant, due to the fact that certain parts and structures of turbine regulation system, lubrication system, turbine runner and measurement system are subject to one of the above mentioned directives. This paper contains the overview and basic parameters of new and general approach to standardization and technical harmonization of hydro power plant equipment that refers to structural integrity.",
publisher = "Institut IMK "14. oktobar", Kruševac",
journal = "IMK-14 - Istraživanje i razvoj",
title = "Guidelines for technical regulations and standardization of turbine and hydromechanical equipment during production and exploitation",
pages = "7-1",
number = "1",
volume = "20",
doi = "10.5937/IMK1401001A"
}

Arsić, M., Vistać, B., Bošnjak, S., Bošković, G.,& Savić, Z.. (2014). Guidelines for technical regulations and standardization of turbine and hydromechanical equipment during production and exploitation. in IMK-14 - Istraživanje i razvoj
Institut IMK "14. oktobar", Kruševac., 20(1), 1-7.
https://doi.org/10.5937/IMK1401001A

Arsić M, Vistać B, Bošnjak S, Bošković G, Savić Z. Guidelines for technical regulations and standardization of turbine and hydromechanical equipment during production and exploitation. in IMK-14 - Istraživanje i razvoj. 2014;20(1):1-7.
doi:10.5937/IMK1401001A .

Arsić, Miodrag, Vistać, Brane, Bošnjak, Srđan, Bošković, Goran, Savić, Zoran, "Guidelines for technical regulations and standardization of turbine and hydromechanical equipment during production and exploitation" in IMK-14 - Istraživanje i razvoj, 20, no. 1 (2014):1-7,
https://doi.org/10.5937/IMK1401001A . .

TY  - JOUR
AU  - Bošnjak, Srđan
AU  - Momčilović, Dejan
AU  - Petković, Zoran D.
AU  - Pantelić, Milorad P.
AU  - Gnjatović, Nebojša
PY  - 2013
UR  - http://rims.institutims.rs/handle/123456789/218
AB  - The high mobility of open pit machines in heavy duty conditions provides fertile ground for the occurrence of various failures of the traveling mechanisms' vital parts such as chain links. The goal of the study presented in this paper was to diagnose the cause of the damage of the bucket wheel excavator crawler chain links. In order to identify the reasons behind chain link failures, stress state calculations were performed as well as experimental investigations which, given the nature of the failure, included visual and metallographic examinations, chemical composition analysis and tests of mechanical properties. Based on the results of the numerical-experimental analyses, it was concluded that the chain link breakdowns are caused by 'manufacturing-in' defects. The results of the presented analyses also emphasize the importance of a comprehensive quality control of chain links.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Engineering Failure Analysis
T1  - Failure investigation of the bucket wheel excavator crawler chain link
EP  - 469
SP  - 462
VL  - 35
DO  - 10.1016/j.engfailanal.2013.04.025
ER  - 

@article{
author = "Bošnjak, Srđan and Momčilović, Dejan and Petković, Zoran D. and Pantelić, Milorad P. and Gnjatović, Nebojša",
year = "2013",
abstract = "The high mobility of open pit machines in heavy duty conditions provides fertile ground for the occurrence of various failures of the traveling mechanisms' vital parts such as chain links. The goal of the study presented in this paper was to diagnose the cause of the damage of the bucket wheel excavator crawler chain links. In order to identify the reasons behind chain link failures, stress state calculations were performed as well as experimental investigations which, given the nature of the failure, included visual and metallographic examinations, chemical composition analysis and tests of mechanical properties. Based on the results of the numerical-experimental analyses, it was concluded that the chain link breakdowns are caused by 'manufacturing-in' defects. The results of the presented analyses also emphasize the importance of a comprehensive quality control of chain links.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Engineering Failure Analysis",
title = "Failure investigation of the bucket wheel excavator crawler chain link",
pages = "469-462",
volume = "35",
doi = "10.1016/j.engfailanal.2013.04.025"
}

Bošnjak, S., Momčilović, D., Petković, Z. D., Pantelić, M. P.,& Gnjatović, N.. (2013). Failure investigation of the bucket wheel excavator crawler chain link. in Engineering Failure Analysis
Pergamon-Elsevier Science Ltd, Oxford., 35, 462-469.
https://doi.org/10.1016/j.engfailanal.2013.04.025

Bošnjak S, Momčilović D, Petković ZD, Pantelić MP, Gnjatović N. Failure investigation of the bucket wheel excavator crawler chain link. in Engineering Failure Analysis. 2013;35:462-469.
doi:10.1016/j.engfailanal.2013.04.025 .

Bošnjak, Srđan, Momčilović, Dejan, Petković, Zoran D., Pantelić, Milorad P., Gnjatović, Nebojša, "Failure investigation of the bucket wheel excavator crawler chain link" in Engineering Failure Analysis, 35 (2013):462-469,
https://doi.org/10.1016/j.engfailanal.2013.04.025 . .

TY  - CONF
AU  - Arsić, Miodrag
AU  - Odanović, Zoran
AU  - Bošnjak, Srđan
AU  - Mladenović, Mladen
AU  - Savić, Zoran
PY  - 2013
UR  - http://rims.institutims.rs/handle/123456789/209
AB  - During the refurbishment of the hydroelectric generating set A6 on HPP "Djerdap 1", for the state analysis and assessment of the level and causes of degradation of the structure of the vertical Kaplan turbine runner guide vane apparatus non-destructive tests and inspections, as well as destructive tests of base material and welded joints, have been carried out after 40 years of service. Results of non-destructive tests performed on welded joints are presented in this paper (magnetic particle and ultrasonic inspection), as well as results of destructive tests of the base material and welded joints (testing of tensile properties, impact testing, metallographic analyses of the structure). A large number of crack type line indications were detected by magnetic particle inspections, while the occurrence of partial penetration in roots of welded joints was detected by ultrasonic inspections, as well as lamellar tearing of the base material. Tensile properties of tested samples taken in longitudinal and transverse direction fulfilled the requirements of the standard with certain deviations, which does not stand for samples taken in z-direction with significantly lower values of contraction of the cross-section than minimum prescribed values, which proves that base material is not resistant to the occurrence of lamellar cracks. Metallographic tests performed on specimens taken from the base material in longitudinal and transverse direction showed that the microstructure is stripe-shaped and ferrite-pearlite with non-metallic inclusions of oxide, sulphide, silicate and aluminate type, while metallographic tests performed on specimens taken from welded joints showed that their microstructure is stripe-shaped and ferrite-pearlite with non-metallic inclusions of oxide type. A large number of micro- and macro-cracks were detected in the microstructure as well. Experimental tests enabled the determination of the causes of occurrence of lamellar tearing in base material and crack type defects in welded joints, while analytical calculation that refers to the stress state enabled integrity of welded structure of the upper ring of the turbine runner guide vane apparatus.
PB  - Trans Tech Publications Ltd, Durnten-Zurich
C3  - Structural Integrity of Welded Structures
T1  - State Analysis and Integrity of Welded Structures of the Upper Ring of the Turbine Runner Guide Vane Apparatus of Hydroelectric Generating Set A6 on Hydro Power Plant Djerdap 1
EP  - +
SP  - 7
VL  - 814
DO  - 10.4028/www.scientific.net/AMR.814.7
ER  - 

@conference{
author = "Arsić, Miodrag and Odanović, Zoran and Bošnjak, Srđan and Mladenović, Mladen and Savić, Zoran",
year = "2013",
abstract = "During the refurbishment of the hydroelectric generating set A6 on HPP "Djerdap 1", for the state analysis and assessment of the level and causes of degradation of the structure of the vertical Kaplan turbine runner guide vane apparatus non-destructive tests and inspections, as well as destructive tests of base material and welded joints, have been carried out after 40 years of service. Results of non-destructive tests performed on welded joints are presented in this paper (magnetic particle and ultrasonic inspection), as well as results of destructive tests of the base material and welded joints (testing of tensile properties, impact testing, metallographic analyses of the structure). A large number of crack type line indications were detected by magnetic particle inspections, while the occurrence of partial penetration in roots of welded joints was detected by ultrasonic inspections, as well as lamellar tearing of the base material. Tensile properties of tested samples taken in longitudinal and transverse direction fulfilled the requirements of the standard with certain deviations, which does not stand for samples taken in z-direction with significantly lower values of contraction of the cross-section than minimum prescribed values, which proves that base material is not resistant to the occurrence of lamellar cracks. Metallographic tests performed on specimens taken from the base material in longitudinal and transverse direction showed that the microstructure is stripe-shaped and ferrite-pearlite with non-metallic inclusions of oxide, sulphide, silicate and aluminate type, while metallographic tests performed on specimens taken from welded joints showed that their microstructure is stripe-shaped and ferrite-pearlite with non-metallic inclusions of oxide type. A large number of micro- and macro-cracks were detected in the microstructure as well. Experimental tests enabled the determination of the causes of occurrence of lamellar tearing in base material and crack type defects in welded joints, while analytical calculation that refers to the stress state enabled integrity of welded structure of the upper ring of the turbine runner guide vane apparatus.",
publisher = "Trans Tech Publications Ltd, Durnten-Zurich",
journal = "Structural Integrity of Welded Structures",
title = "State Analysis and Integrity of Welded Structures of the Upper Ring of the Turbine Runner Guide Vane Apparatus of Hydroelectric Generating Set A6 on Hydro Power Plant Djerdap 1",
pages = "+-7",
volume = "814",
doi = "10.4028/www.scientific.net/AMR.814.7"
}

Arsić, M., Odanović, Z., Bošnjak, S., Mladenović, M.,& Savić, Z.. (2013). State Analysis and Integrity of Welded Structures of the Upper Ring of the Turbine Runner Guide Vane Apparatus of Hydroelectric Generating Set A6 on Hydro Power Plant Djerdap 1. in Structural Integrity of Welded Structures
Trans Tech Publications Ltd, Durnten-Zurich., 814, 7-+.
https://doi.org/10.4028/www.scientific.net/AMR.814.7

Arsić M, Odanović Z, Bošnjak S, Mladenović M, Savić Z. State Analysis and Integrity of Welded Structures of the Upper Ring of the Turbine Runner Guide Vane Apparatus of Hydroelectric Generating Set A6 on Hydro Power Plant Djerdap 1. in Structural Integrity of Welded Structures. 2013;814:7-+.
doi:10.4028/www.scientific.net/AMR.814.7 .

Arsić, Miodrag, Odanović, Zoran, Bošnjak, Srđan, Mladenović, Mladen, Savić, Zoran, "State Analysis and Integrity of Welded Structures of the Upper Ring of the Turbine Runner Guide Vane Apparatus of Hydroelectric Generating Set A6 on Hydro Power Plant Djerdap 1" in Structural Integrity of Welded Structures, 814 (2013):7-+,
https://doi.org/10.4028/www.scientific.net/AMR.814.7 . .

TY  - JOUR
AU  - Bošnjak, Srđan
AU  - Zrnić, Nenad
AU  - Simonović, Aleksandar
AU  - Momčilović, Dejan
PY  - 2009
UR  - http://rims.institutims.rs/handle/123456789/100
AB  - This paper describes the failure analysis results of the bucket wheel excavator (BWE) portal tie-rod support. The results of finite elements analysis (FEA) point out the occurrence of pronounced stress concentration, whereby multiple stresses in the failure zone exceed the yield stress of the basic material. Experimental investigation on fracture surfaces by scanning electron microscope (SEM) and light microscope (LM) revealed the existence of porosities and inclusions in the weld metal. Moreover, various types of fracture (fatigue, transition, brittle) and their uneven fraction observed on fracture surfaces are induced by structural characteristics of the base metal, welding technology and the construction itself. Based on the presented results it is conclusive that the failure of the support was the consequence of superposition of the negative effects caused by inadequate shaping and dimensioning of the support assembly for given load conditions, as well as influences of mentioned defects of the metal weld structure.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Engineering Failure Analysis
T1  - Failure analysis of the end eye connection of the bucket wheel excavator portal tie-rod support
EP  - 750
IS  - 3
SP  - 740
VL  - 16
DO  - 10.1016/j.engfailanal.2008.06.006
ER  - 

@article{
author = "Bošnjak, Srđan and Zrnić, Nenad and Simonović, Aleksandar and Momčilović, Dejan",
year = "2009",
abstract = "This paper describes the failure analysis results of the bucket wheel excavator (BWE) portal tie-rod support. The results of finite elements analysis (FEA) point out the occurrence of pronounced stress concentration, whereby multiple stresses in the failure zone exceed the yield stress of the basic material. Experimental investigation on fracture surfaces by scanning electron microscope (SEM) and light microscope (LM) revealed the existence of porosities and inclusions in the weld metal. Moreover, various types of fracture (fatigue, transition, brittle) and their uneven fraction observed on fracture surfaces are induced by structural characteristics of the base metal, welding technology and the construction itself. Based on the presented results it is conclusive that the failure of the support was the consequence of superposition of the negative effects caused by inadequate shaping and dimensioning of the support assembly for given load conditions, as well as influences of mentioned defects of the metal weld structure.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Engineering Failure Analysis",
title = "Failure analysis of the end eye connection of the bucket wheel excavator portal tie-rod support",
pages = "750-740",
number = "3",
volume = "16",
doi = "10.1016/j.engfailanal.2008.06.006"
}

Bošnjak, S., Zrnić, N., Simonović, A.,& Momčilović, D.. (2009). Failure analysis of the end eye connection of the bucket wheel excavator portal tie-rod support. in Engineering Failure Analysis
Pergamon-Elsevier Science Ltd, Oxford., 16(3), 740-750.
https://doi.org/10.1016/j.engfailanal.2008.06.006

Bošnjak S, Zrnić N, Simonović A, Momčilović D. Failure analysis of the end eye connection of the bucket wheel excavator portal tie-rod support. in Engineering Failure Analysis. 2009;16(3):740-750.
doi:10.1016/j.engfailanal.2008.06.006 .

Bošnjak, Srđan, Zrnić, Nenad, Simonović, Aleksandar, Momčilović, Dejan, "Failure analysis of the end eye connection of the bucket wheel excavator portal tie-rod support" in Engineering Failure Analysis, 16, no. 3 (2009):740-750,
https://doi.org/10.1016/j.engfailanal.2008.06.006 . .