TY  - JOUR
AU  - Sedmak, Aleksandar
AU  - Grbović, Aleksandar
AU  - Petrovski, Blagoj
AU  - Sghayer, Abulgasem
AU  - Sedmak, Simon
AU  - Berto, Filippo
AU  - Đurđević, A.
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3813
AB  - Fatigue crack growth in different panels, made of AA6156 T6, was investigated experimentally and numerically. Three different types of panels were used, simple one, so-called base metal (BM), panel with 4 welded stringers and panel with 4 welded stringers and 3 welded clips. Experimental investigation indicated benefits of stringers, especially in respect to residual life, since the number of cycles were more than doubled (420 Kcyc vs 195 Kcyc for initial crack length 14 mm), but that was not the case for panels with clips (220 Kcyc). Experimental investigation was also performed on panels with longer cracks (75 mm) to check the effect of initial crack length in the case of BM and panels with 4 stringers, showing practically the same effect of stringers on residual life (95 Kcyc vs 50 Kcyc). Then, fatigue crack growth in panels was simulated numerically using xFEM. Numerical simulation indicated the same trend and effectiveness of stringers, with sufficient agreement with experimental results for BM and panels with stringers only. Anyhow in the case of clips panels with 4 stringers and 3 clips, number of cycles for panel with additional 3-clips was higher than for panel with just 4-stringer, (278 Kcyc vs 265 Kcyc), improving fatigue life for cca 5 %, contrary to experimental results.
PB  - Elsevier Ltd
T2  - International Journal of Fatigue
T1  - The effects of welded clips on fatigue crack growth in AA6156 T6 panels
VL  - 165
DO  - 10.1016/j.ijfatigue.2022.107162
ER  - 

@article{
author = "Sedmak, Aleksandar and Grbović, Aleksandar and Petrovski, Blagoj and Sghayer, Abulgasem and Sedmak, Simon and Berto, Filippo and Đurđević, A.",
year = "2022",
abstract = "Fatigue crack growth in different panels, made of AA6156 T6, was investigated experimentally and numerically. Three different types of panels were used, simple one, so-called base metal (BM), panel with 4 welded stringers and panel with 4 welded stringers and 3 welded clips. Experimental investigation indicated benefits of stringers, especially in respect to residual life, since the number of cycles were more than doubled (420 Kcyc vs 195 Kcyc for initial crack length 14 mm), but that was not the case for panels with clips (220 Kcyc). Experimental investigation was also performed on panels with longer cracks (75 mm) to check the effect of initial crack length in the case of BM and panels with 4 stringers, showing practically the same effect of stringers on residual life (95 Kcyc vs 50 Kcyc). Then, fatigue crack growth in panels was simulated numerically using xFEM. Numerical simulation indicated the same trend and effectiveness of stringers, with sufficient agreement with experimental results for BM and panels with stringers only. Anyhow in the case of clips panels with 4 stringers and 3 clips, number of cycles for panel with additional 3-clips was higher than for panel with just 4-stringer, (278 Kcyc vs 265 Kcyc), improving fatigue life for cca 5 %, contrary to experimental results.",
publisher = "Elsevier Ltd",
journal = "International Journal of Fatigue",
title = "The effects of welded clips on fatigue crack growth in AA6156 T6 panels",
volume = "165",
doi = "10.1016/j.ijfatigue.2022.107162"
}

Sedmak, A., Grbović, A., Petrovski, B., Sghayer, A., Sedmak, S., Berto, F.,& Đurđević, A.. (2022). The effects of welded clips on fatigue crack growth in AA6156 T6 panels. in International Journal of Fatigue
Elsevier Ltd., 165.
https://doi.org/10.1016/j.ijfatigue.2022.107162

Sedmak A, Grbović A, Petrovski B, Sghayer A, Sedmak S, Berto F, Đurđević A. The effects of welded clips on fatigue crack growth in AA6156 T6 panels. in International Journal of Fatigue. 2022;165.
doi:10.1016/j.ijfatigue.2022.107162 .

Sedmak, Aleksandar, Grbović, Aleksandar, Petrovski, Blagoj, Sghayer, Abulgasem, Sedmak, Simon, Berto, Filippo, Đurđević, A., "The effects of welded clips on fatigue crack growth in AA6156 T6 panels" in International Journal of Fatigue, 165 (2022),
https://doi.org/10.1016/j.ijfatigue.2022.107162 . .

TY  - JOUR
AU  - Grbović, Aleksandar
AU  - Sedmak, Aleksandar
AU  - Sghayer, Abulgasem
AU  - Čolić, Katarina
PY  - 2022
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3756
AB  - Relevantne lokalne karakteristike zamornog opterećenja su najveći amplitudni napon i odgovrajauća srednja vrednost napona, koje treba odrediti za celu komponentu. Relevantna svojtva materijala se onda upoređuju sa dobijenim naponima, na osnovu čega je procenjen integritet i vek panela od Al legure sa zavarenim ukrućenjem. Za određivanje najvećih napona korišćena je metoda konačnih elemenata.
AB  - Relevant local characteristics of fatigue loading are the largest stress amplitudes in the related mean stress values. They should be determined for the whole components. The relevant material properties are then compared with the stresses to assess integrity and life of a panel, made of Al allow, with welded stringers. To determine the maximum stresses the Finite Element Method was used.
PB  - DUZS - Društvo za unapređivanje zavarivanja u Srbiji, Beograd
T2  - Zavarivanje i zavarene konstrukcije
T1  - Procena integriteta i veka zavarenog panela primenom lokalnih napona
T1  - Assessment of the integrity and life of welded panel using local stresses
EP  - 19
IS  - 1
SP  - 11
VL  - 67
DO  - 10.5937/zzk2201011G
ER  - 

@article{
author = "Grbović, Aleksandar and Sedmak, Aleksandar and Sghayer, Abulgasem and Čolić, Katarina",
year = "2022",
abstract = "Relevantne lokalne karakteristike zamornog opterećenja su najveći amplitudni napon i odgovrajauća srednja vrednost napona, koje treba odrediti za celu komponentu. Relevantna svojtva materijala se onda upoređuju sa dobijenim naponima, na osnovu čega je procenjen integritet i vek panela od Al legure sa zavarenim ukrućenjem. Za određivanje najvećih napona korišćena je metoda konačnih elemenata., Relevant local characteristics of fatigue loading are the largest stress amplitudes in the related mean stress values. They should be determined for the whole components. The relevant material properties are then compared with the stresses to assess integrity and life of a panel, made of Al allow, with welded stringers. To determine the maximum stresses the Finite Element Method was used.",
publisher = "DUZS - Društvo za unapređivanje zavarivanja u Srbiji, Beograd",
journal = "Zavarivanje i zavarene konstrukcije",
title = "Procena integriteta i veka zavarenog panela primenom lokalnih napona, Assessment of the integrity and life of welded panel using local stresses",
pages = "19-11",
number = "1",
volume = "67",
doi = "10.5937/zzk2201011G"
}

Grbović, A., Sedmak, A., Sghayer, A.,& Čolić, K.. (2022). Procena integriteta i veka zavarenog panela primenom lokalnih napona. in Zavarivanje i zavarene konstrukcije
DUZS - Društvo za unapređivanje zavarivanja u Srbiji, Beograd., 67(1), 11-19.
https://doi.org/10.5937/zzk2201011G

Grbović A, Sedmak A, Sghayer A, Čolić K. Procena integriteta i veka zavarenog panela primenom lokalnih napona. in Zavarivanje i zavarene konstrukcije. 2022;67(1):11-19.
doi:10.5937/zzk2201011G .

Grbović, Aleksandar, Sedmak, Aleksandar, Sghayer, Abulgasem, Čolić, Katarina, "Procena integriteta i veka zavarenog panela primenom lokalnih napona" in Zavarivanje i zavarene konstrukcije, 67, no. 1 (2022):11-19,
https://doi.org/10.5937/zzk2201011G . .

TY  - CONF
AU  - Grbović, Aleksandar
AU  - Sedmak, Aleksandar
AU  - Petrovski, Blagoj
AU  - Sghayer, Abulgasem
AU  - Sedmak, Simon
AU  - Razavi, J.
AU  - Berto, Filippo
PY  - 2021
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3657
AB  - Fatigue crack growth in a panel with 4 stringers and 3-clips, made of AA6156 T6, was modelled numerically using xFEM. The central crack of the length a=17 mm was propagated in the total of 91 steps (in each step crack length increased by 2 mm) and after 14 steps the first clip began to deform. At the same time, crack continued to grow through the base plate, reaching the right and left stringers after 91 steps and beginning to grow along those stringers. Number of cycles for panel with additional 3-clips was higher than for panel with just 4-stringer, (278476 cycles vs. 2649587) cycles, improving fatigue life for cca 5%.
PB  - Elsevier B.V.
C3  - Procedia Structural Integrity
T1  - Numerical simulation of fatigue crack growth in AA6156 T6 panels
EP  - 791
IS  - C
SP  - 786
VL  - 39
DO  - 10.1016/j.prostr.2022.03.155
ER  - 

@conference{
author = "Grbović, Aleksandar and Sedmak, Aleksandar and Petrovski, Blagoj and Sghayer, Abulgasem and Sedmak, Simon and Razavi, J. and Berto, Filippo",
year = "2021",
abstract = "Fatigue crack growth in a panel with 4 stringers and 3-clips, made of AA6156 T6, was modelled numerically using xFEM. The central crack of the length a=17 mm was propagated in the total of 91 steps (in each step crack length increased by 2 mm) and after 14 steps the first clip began to deform. At the same time, crack continued to grow through the base plate, reaching the right and left stringers after 91 steps and beginning to grow along those stringers. Number of cycles for panel with additional 3-clips was higher than for panel with just 4-stringer, (278476 cycles vs. 2649587) cycles, improving fatigue life for cca 5%.",
publisher = "Elsevier B.V.",
journal = "Procedia Structural Integrity",
title = "Numerical simulation of fatigue crack growth in AA6156 T6 panels",
pages = "791-786",
number = "C",
volume = "39",
doi = "10.1016/j.prostr.2022.03.155"
}

Grbović, A., Sedmak, A., Petrovski, B., Sghayer, A., Sedmak, S., Razavi, J.,& Berto, F.. (2021). Numerical simulation of fatigue crack growth in AA6156 T6 panels. in Procedia Structural Integrity
Elsevier B.V.., 39(C), 786-791.
https://doi.org/10.1016/j.prostr.2022.03.155

Grbović A, Sedmak A, Petrovski B, Sghayer A, Sedmak S, Razavi J, Berto F. Numerical simulation of fatigue crack growth in AA6156 T6 panels. in Procedia Structural Integrity. 2021;39(C):786-791.
doi:10.1016/j.prostr.2022.03.155 .

Grbović, Aleksandar, Sedmak, Aleksandar, Petrovski, Blagoj, Sghayer, Abulgasem, Sedmak, Simon, Razavi, J., Berto, Filippo, "Numerical simulation of fatigue crack growth in AA6156 T6 panels" in Procedia Structural Integrity, 39, no. C (2021):786-791,
https://doi.org/10.1016/j.prostr.2022.03.155 . .

TY  - JOUR
AU  - Grbović, Aleksandar
AU  - Sedmak, Aleksandar
AU  - Kastratović, Gordana
AU  - Petrašinović, Danilo
AU  - Vidanović, Nenad
AU  - Sghayer, Abulgasem
PY  - 2019
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/3135
AB  - In this paper, numerical analyses of fatigue crack growth in integral skin-stringer panel produced by means of laser beam welding (LBW) are presented along with fatigue results verified by previously conducted experiments. Skin-stringer panel is fail-safe structure widely used in aircraft industry, which requires a good estimate of fatigue life after crack initiation. In the past, experimental work was the only successful method for fatigue life estimation of complex damaged structure, but nowadays researches have powerful numerical tools, such as extended finite element method (XFEM), for three-dimensional crack growth analysis. In research presented here, XFEM was initially used for crack growth simulation in simple flat plate made of aluminium 6156 T6 and 6156 T4 for the purpose of procedure verification, since fatigue life for simple plate was known from experiment. Then, XFEM was used to simulate fatigue crack growth in the panel reinforced with four stringers. Fatigue life obtained on the basis of calculated stress intensity factors (SIFS) along the crack fronts on LBW skin-stringer panels was, as expected, significantly longer than experimentally measured life of simple flat plate. Finally, several numerical simulations were performed in order to analyse the influence of mesh size on accuracy of estimated fatigue life of damaged LBW skin panels. For that purpose, average element sizes of 1, 2 and 4 mm were used.
PB  - Pergamon-Elsevier Science Ltd, Oxford
T2  - Engineering Failure Analysis
T1  - Effect of laser beam welded reinforcement on integral skin panel fatigue life
EP  - 393
SP  - 383
VL  - 101
DO  - 10.1016/j.engfailanal.2019.03.029
ER  - 

@article{
author = "Grbović, Aleksandar and Sedmak, Aleksandar and Kastratović, Gordana and Petrašinović, Danilo and Vidanović, Nenad and Sghayer, Abulgasem",
year = "2019",
abstract = "In this paper, numerical analyses of fatigue crack growth in integral skin-stringer panel produced by means of laser beam welding (LBW) are presented along with fatigue results verified by previously conducted experiments. Skin-stringer panel is fail-safe structure widely used in aircraft industry, which requires a good estimate of fatigue life after crack initiation. In the past, experimental work was the only successful method for fatigue life estimation of complex damaged structure, but nowadays researches have powerful numerical tools, such as extended finite element method (XFEM), for three-dimensional crack growth analysis. In research presented here, XFEM was initially used for crack growth simulation in simple flat plate made of aluminium 6156 T6 and 6156 T4 for the purpose of procedure verification, since fatigue life for simple plate was known from experiment. Then, XFEM was used to simulate fatigue crack growth in the panel reinforced with four stringers. Fatigue life obtained on the basis of calculated stress intensity factors (SIFS) along the crack fronts on LBW skin-stringer panels was, as expected, significantly longer than experimentally measured life of simple flat plate. Finally, several numerical simulations were performed in order to analyse the influence of mesh size on accuracy of estimated fatigue life of damaged LBW skin panels. For that purpose, average element sizes of 1, 2 and 4 mm were used.",
publisher = "Pergamon-Elsevier Science Ltd, Oxford",
journal = "Engineering Failure Analysis",
title = "Effect of laser beam welded reinforcement on integral skin panel fatigue life",
pages = "393-383",
volume = "101",
doi = "10.1016/j.engfailanal.2019.03.029"
}

Grbović, A., Sedmak, A., Kastratović, G., Petrašinović, D., Vidanović, N.,& Sghayer, A.. (2019). Effect of laser beam welded reinforcement on integral skin panel fatigue life. in Engineering Failure Analysis
Pergamon-Elsevier Science Ltd, Oxford., 101, 383-393.
https://doi.org/10.1016/j.engfailanal.2019.03.029

Grbović A, Sedmak A, Kastratović G, Petrašinović D, Vidanović N, Sghayer A. Effect of laser beam welded reinforcement on integral skin panel fatigue life. in Engineering Failure Analysis. 2019;101:383-393.
doi:10.1016/j.engfailanal.2019.03.029 .

Grbović, Aleksandar, Sedmak, Aleksandar, Kastratović, Gordana, Petrašinović, Danilo, Vidanović, Nenad, Sghayer, Abulgasem, "Effect of laser beam welded reinforcement on integral skin panel fatigue life" in Engineering Failure Analysis, 101 (2019):383-393,
https://doi.org/10.1016/j.engfailanal.2019.03.029 . .

TY  - JOUR
AU  - Sghayer, Abulgasem
AU  - Grbović, Aleksandar
AU  - Sedmak, Aleksandar
AU  - Dinulović, Mirko
AU  - Grozdanović, Ines
AU  - Sedmak, Simon
AU  - Petrovski, Blagoj
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2758
AB  - Experimental and numerical analysis of fatigue crack growth in integral skin-stringer panels, produced by means of laser beam welding (LBW), is performed. Since this type of panel is used in airframe construction, fatigue and damage tolerance is of paramount importance, since aircrafts must be tolerant to relatively large fatigue cracks. Firstly, using extended finite element method (XFEM), the fatigue crack growth on the simple flat plate made of AL-AA 6156T6/ 2.8 mm was simulated, and results were compared with values obtained in the experiment. The same approach was taken to simulate the fatigue behaviour and crack propagation of the real skinstringer panel (four stringers, laser beam welded). It was found that the results obtained for stress intensity factors (SIFs) KI, KII, KIII and Keff along the crack front, are close to the experimental results, leading to conclusion that the XFEM method can be successfully used in prediction of fatigue life of complex airframe structures, such as laserbeam welded skin-stringer panels.
PB  - Univ Osijek, Tech Fac, Slavonski Brod
T2  - Tehnički vjesnik
T1  - Experimental and Numerical Analysis of Fatigue Crack Growth in Integral Skin-Stringer Panels
EP  - 791
IS  - 3
SP  - 785
VL  - 25
DO  - 10.17559/TV-20170308110329
ER  - 

@article{
author = "Sghayer, Abulgasem and Grbović, Aleksandar and Sedmak, Aleksandar and Dinulović, Mirko and Grozdanović, Ines and Sedmak, Simon and Petrovski, Blagoj",
year = "2018",
abstract = "Experimental and numerical analysis of fatigue crack growth in integral skin-stringer panels, produced by means of laser beam welding (LBW), is performed. Since this type of panel is used in airframe construction, fatigue and damage tolerance is of paramount importance, since aircrafts must be tolerant to relatively large fatigue cracks. Firstly, using extended finite element method (XFEM), the fatigue crack growth on the simple flat plate made of AL-AA 6156T6/ 2.8 mm was simulated, and results were compared with values obtained in the experiment. The same approach was taken to simulate the fatigue behaviour and crack propagation of the real skinstringer panel (four stringers, laser beam welded). It was found that the results obtained for stress intensity factors (SIFs) KI, KII, KIII and Keff along the crack front, are close to the experimental results, leading to conclusion that the XFEM method can be successfully used in prediction of fatigue life of complex airframe structures, such as laserbeam welded skin-stringer panels.",
publisher = "Univ Osijek, Tech Fac, Slavonski Brod",
journal = "Tehnički vjesnik",
title = "Experimental and Numerical Analysis of Fatigue Crack Growth in Integral Skin-Stringer Panels",
pages = "791-785",
number = "3",
volume = "25",
doi = "10.17559/TV-20170308110329"
}

Sghayer, A., Grbović, A., Sedmak, A., Dinulović, M., Grozdanović, I., Sedmak, S.,& Petrovski, B.. (2018). Experimental and Numerical Analysis of Fatigue Crack Growth in Integral Skin-Stringer Panels. in Tehnički vjesnik
Univ Osijek, Tech Fac, Slavonski Brod., 25(3), 785-791.
https://doi.org/10.17559/TV-20170308110329

Sghayer A, Grbović A, Sedmak A, Dinulović M, Grozdanović I, Sedmak S, Petrovski B. Experimental and Numerical Analysis of Fatigue Crack Growth in Integral Skin-Stringer Panels. in Tehnički vjesnik. 2018;25(3):785-791.
doi:10.17559/TV-20170308110329 .

Sghayer, Abulgasem, Grbović, Aleksandar, Sedmak, Aleksandar, Dinulović, Mirko, Grozdanović, Ines, Sedmak, Simon, Petrovski, Blagoj, "Experimental and Numerical Analysis of Fatigue Crack Growth in Integral Skin-Stringer Panels" in Tehnički vjesnik, 25, no. 3 (2018):785-791,
https://doi.org/10.17559/TV-20170308110329 . .

TY  - JOUR
AU  - Sghayer, Abulgasem
AU  - Grbović, Aleksandar
AU  - Sedmak, Aleksandar
AU  - Dinulović, Mirko
AU  - Doncheva, Elisaveta
AU  - Petrovski, Blagoj
PY  - 2017
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/2711
AB  - Fatigue life of integral skin-stringer panels produced by laser beam welding (LBW) is analysed. This type of panel is used in airframe construction where fatigue and damage tolerance are of paramount importance, since aircrafts must be designed to tolerate relatively large fatigue cracks. The analysed integral skin-stringer panel is made of AL-AA 6156T6/2.8 mm, where stringers are laser beam welded to the airframe skin. By using the extended finite element method (XFEM), fatigue life of simple flat plate, as well of the skin-stringer panel, are numerically simulated in order to investigate the effect of stringers.
PB  - Institut za ispitivanje materijala, Beograd
T2  - Structural Integrity and Life
T1  - Fatigue life analysis of the integral skin-stringer panel using xfem
EP  - 10
IS  - 1
SP  - 7
VL  - 17
UR  - https://hdl.handle.net/21.15107/rcub_machinery_2711
ER  - 

@article{
author = "Sghayer, Abulgasem and Grbović, Aleksandar and Sedmak, Aleksandar and Dinulović, Mirko and Doncheva, Elisaveta and Petrovski, Blagoj",
year = "2017",
abstract = "Fatigue life of integral skin-stringer panels produced by laser beam welding (LBW) is analysed. This type of panel is used in airframe construction where fatigue and damage tolerance are of paramount importance, since aircrafts must be designed to tolerate relatively large fatigue cracks. The analysed integral skin-stringer panel is made of AL-AA 6156T6/2.8 mm, where stringers are laser beam welded to the airframe skin. By using the extended finite element method (XFEM), fatigue life of simple flat plate, as well of the skin-stringer panel, are numerically simulated in order to investigate the effect of stringers.",
publisher = "Institut za ispitivanje materijala, Beograd",
journal = "Structural Integrity and Life",
title = "Fatigue life analysis of the integral skin-stringer panel using xfem",
pages = "10-7",
number = "1",
volume = "17",
url = "https://hdl.handle.net/21.15107/rcub_machinery_2711"
}

Sghayer, A., Grbović, A., Sedmak, A., Dinulović, M., Doncheva, E.,& Petrovski, B.. (2017). Fatigue life analysis of the integral skin-stringer panel using xfem. in Structural Integrity and Life
Institut za ispitivanje materijala, Beograd., 17(1), 7-10.
https://hdl.handle.net/21.15107/rcub_machinery_2711

Sghayer A, Grbović A, Sedmak A, Dinulović M, Doncheva E, Petrovski B. Fatigue life analysis of the integral skin-stringer panel using xfem. in Structural Integrity and Life. 2017;17(1):7-10.
https://hdl.handle.net/21.15107/rcub_machinery_2711 .

Sghayer, Abulgasem, Grbović, Aleksandar, Sedmak, Aleksandar, Dinulović, Mirko, Doncheva, Elisaveta, Petrovski, Blagoj, "Fatigue life analysis of the integral skin-stringer panel using xfem" in Structural Integrity and Life, 17, no. 1 (2017):7-10,
https://hdl.handle.net/21.15107/rcub_machinery_2711 .