TY  - JOUR
AU  - Perković, Srđa
AU  - Sedmak, Aleksandar
AU  - Radaković, Zoran
AU  - Burzić, Zijah
AU  - Sedmak, Simon
AU  - Radović, Ljubica
AU  - Mandić, Ivana
PY  - 2023
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/6886
AB  - The search for alternative materials that can be used for parts of aircraft hydraulic systems has led to the idea of applying S32750 duplex steel for this purpose. This steel is mainly used in the oil and gas, chemical, and food industries. The reasons for this lie in this material’s exceptional welding, mechanical, and corrosion resistance properties. In order to verify this material’s suitability for aircraft engineering applications, it is necessary to investigate its behaviour at various temperatures, since aircrafts operate at a wide range of temperatures. For this reason, the effect of temperatures in the range from +20 °C to −80 °C on impact toughness was investigated in the case of S32750 duplex steel and its welded joints. Testing was performed using an instrumented pendulum to obtain force-time and energy-time diagrams, which allowed for more detailed assessment of the effect of testing temperature on total impact energy and its components of crack initiation energy and crack propagation energy. Testing was performed on standard Charpy specimens extracted from base metal (BM), welded metal (WM), and the heat-affected zone (HAZ). The results of these tests indicated high values of both crack initiation and propagation energies at room temperature for all the zones (BM, WM, and HAZ) and sufficient levels of crack propagation and total impact energies above −50 °C. In addition, fractography was conducted through optical microscopy (OM) and scanning electron microscopy (SEM), indicating ductile vs. cleavage fracture surface areas, which corresponded well with the impact toughness values. The results of this research confirm that the use of S32750 duplex steel in the manufacturing of aircraft hydraulic systems has considerable potential, and future work should confirm this.
PB  - MDPI
T2  - Materials
T1  - Effect of temperature on S32750 duplex steel welded joint impact toughness
IS  - 12
VL  - 16
DO  - 10.3390/ma16124432
ER  - 

@article{
author = "Perković, Srđa and Sedmak, Aleksandar and Radaković, Zoran and Burzić, Zijah and Sedmak, Simon and Radović, Ljubica and Mandić, Ivana",
year = "2023",
abstract = "The search for alternative materials that can be used for parts of aircraft hydraulic systems has led to the idea of applying S32750 duplex steel for this purpose. This steel is mainly used in the oil and gas, chemical, and food industries. The reasons for this lie in this material’s exceptional welding, mechanical, and corrosion resistance properties. In order to verify this material’s suitability for aircraft engineering applications, it is necessary to investigate its behaviour at various temperatures, since aircrafts operate at a wide range of temperatures. For this reason, the effect of temperatures in the range from +20 °C to −80 °C on impact toughness was investigated in the case of S32750 duplex steel and its welded joints. Testing was performed using an instrumented pendulum to obtain force-time and energy-time diagrams, which allowed for more detailed assessment of the effect of testing temperature on total impact energy and its components of crack initiation energy and crack propagation energy. Testing was performed on standard Charpy specimens extracted from base metal (BM), welded metal (WM), and the heat-affected zone (HAZ). The results of these tests indicated high values of both crack initiation and propagation energies at room temperature for all the zones (BM, WM, and HAZ) and sufficient levels of crack propagation and total impact energies above −50 °C. In addition, fractography was conducted through optical microscopy (OM) and scanning electron microscopy (SEM), indicating ductile vs. cleavage fracture surface areas, which corresponded well with the impact toughness values. The results of this research confirm that the use of S32750 duplex steel in the manufacturing of aircraft hydraulic systems has considerable potential, and future work should confirm this.",
publisher = "MDPI",
journal = "Materials",
title = "Effect of temperature on S32750 duplex steel welded joint impact toughness",
number = "12",
volume = "16",
doi = "10.3390/ma16124432"
}

Perković, S., Sedmak, A., Radaković, Z., Burzić, Z., Sedmak, S., Radović, L.,& Mandić, I.. (2023). Effect of temperature on S32750 duplex steel welded joint impact toughness. in Materials
MDPI., 16(12).
https://doi.org/10.3390/ma16124432

Perković S, Sedmak A, Radaković Z, Burzić Z, Sedmak S, Radović L, Mandić I. Effect of temperature on S32750 duplex steel welded joint impact toughness. in Materials. 2023;16(12).
doi:10.3390/ma16124432 .

Perković, Srđa, Sedmak, Aleksandar, Radaković, Zoran, Burzić, Zijah, Sedmak, Simon, Radović, Ljubica, Mandić, Ivana, "Effect of temperature on S32750 duplex steel welded joint impact toughness" in Materials, 16, no. 12 (2023),
https://doi.org/10.3390/ma16124432 . .

TY  - CONF
AU  - Sedmak, Simon
AU  - Burzić, Zijah
AU  - Perković, Srđa
AU  - Jovičić, Radomir
AU  - Aranđelović, Mihajlo
AU  - Đorđević, Branislav
AU  - Radaković, Zoran
PY  - 2018
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/6490
AB  - In this paper, the results of determining the Paris law coefficients, C and m, is presented, based on the experimental data obtained by three-point bending testing of welded joint specimens made of
P460NL1 steel, with VAC 65 wire used as the filler material. The specimens were made with a 1.4
mm notch in the heat affected zone. After the fatigue crack growth tests performed using the Fractomat 7609/213 (RUMUL), the obtained crack growth rate vs. number of cycles (da/dN vs. N) diagrams were used to calculate the coefficients, for the purpose of using them in numerical simulations that will follow.
C3  - Book of abstracts ICSID 2018 Conference (International conference on structural integrity and durability 2018)
T1  - Experimental Determining of Paris Law Coefficients for Steel P460nl1 Welded Joint Specimens
UR  - https://hdl.handle.net/21.15107/rcub_machinery_6490
ER  - 

@conference{
author = "Sedmak, Simon and Burzić, Zijah and Perković, Srđa and Jovičić, Radomir and Aranđelović, Mihajlo and Đorđević, Branislav and Radaković, Zoran",
year = "2018",
abstract = "In this paper, the results of determining the Paris law coefficients, C and m, is presented, based on the experimental data obtained by three-point bending testing of welded joint specimens made of
P460NL1 steel, with VAC 65 wire used as the filler material. The specimens were made with a 1.4
mm notch in the heat affected zone. After the fatigue crack growth tests performed using the Fractomat 7609/213 (RUMUL), the obtained crack growth rate vs. number of cycles (da/dN vs. N) diagrams were used to calculate the coefficients, for the purpose of using them in numerical simulations that will follow.",
journal = "Book of abstracts ICSID 2018 Conference (International conference on structural integrity and durability 2018)",
title = "Experimental Determining of Paris Law Coefficients for Steel P460nl1 Welded Joint Specimens",
url = "https://hdl.handle.net/21.15107/rcub_machinery_6490"
}

Sedmak, S., Burzić, Z., Perković, S., Jovičić, R., Aranđelović, M., Đorđević, B.,& Radaković, Z.. (2018). Experimental Determining of Paris Law Coefficients for Steel P460nl1 Welded Joint Specimens. in Book of abstracts ICSID 2018 Conference (International conference on structural integrity and durability 2018).
https://hdl.handle.net/21.15107/rcub_machinery_6490

Sedmak S, Burzić Z, Perković S, Jovičić R, Aranđelović M, Đorđević B, Radaković Z. Experimental Determining of Paris Law Coefficients for Steel P460nl1 Welded Joint Specimens. in Book of abstracts ICSID 2018 Conference (International conference on structural integrity and durability 2018). 2018;.
https://hdl.handle.net/21.15107/rcub_machinery_6490 .

Sedmak, Simon, Burzić, Zijah, Perković, Srđa, Jovičić, Radomir, Aranđelović, Mihajlo, Đorđević, Branislav, Radaković, Zoran, "Experimental Determining of Paris Law Coefficients for Steel P460nl1 Welded Joint Specimens" in Book of abstracts ICSID 2018 Conference (International conference on structural integrity and durability 2018) (2018),
https://hdl.handle.net/21.15107/rcub_machinery_6490 .

TY  - CONF
AU  - Sedmak, Simon
AU  - Čamagić, I.
AU  - Sedmak, Aleksandar
AU  - Burzić, Zijah
AU  - Đorđević, Branislav
PY  - 2018
UR  - https://www.researchgate.net/publication/342314767_Fatigue_and_Fracture_at_all_Scales
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/6266
AB  - This paper presents the analysis of the temperature and exploitation time influence on the resistant measure to brittle fracture of welded joint constituents of the new and exploited low-alloyed Cr-Mo steel A-387 Gr. B subjected to variable and impact load. The exploited parent metal is a part of the reactor mantle which has been exploited for over 40 years and is in the damage repair stage. Wohler’s curves are constructed, that is, fatigue strength as the resistance of the material to the crack initiation and the total impact energy, as well as the components, crack initiation energy and crack propagation energy at room and working energy are determined. Based on the research
results, the analysis of the resistance to brittle fracture represents the comparison of obtained values for characteristic areas of welded joint and justification of the selected welding technology
C3  - International Conference on New Trends in Fatigue and Fracture
T1  - The influence of the temperature and exploitation time on the behaviour of a welded joint subjected to variable and impact load
EP  - 182
SP  - 179
UR  - https://hdl.handle.net/21.15107/rcub_machinery_6266
ER  - 

@conference{
author = "Sedmak, Simon and Čamagić, I. and Sedmak, Aleksandar and Burzić, Zijah and Đorđević, Branislav",
year = "2018",
abstract = "This paper presents the analysis of the temperature and exploitation time influence on the resistant measure to brittle fracture of welded joint constituents of the new and exploited low-alloyed Cr-Mo steel A-387 Gr. B subjected to variable and impact load. The exploited parent metal is a part of the reactor mantle which has been exploited for over 40 years and is in the damage repair stage. Wohler’s curves are constructed, that is, fatigue strength as the resistance of the material to the crack initiation and the total impact energy, as well as the components, crack initiation energy and crack propagation energy at room and working energy are determined. Based on the research
results, the analysis of the resistance to brittle fracture represents the comparison of obtained values for characteristic areas of welded joint and justification of the selected welding technology",
journal = "International Conference on New Trends in Fatigue and Fracture",
title = "The influence of the temperature and exploitation time on the behaviour of a welded joint subjected to variable and impact load",
pages = "182-179",
url = "https://hdl.handle.net/21.15107/rcub_machinery_6266"
}

Sedmak, S., Čamagić, I., Sedmak, A., Burzić, Z.,& Đorđević, B.. (2018). The influence of the temperature and exploitation time on the behaviour of a welded joint subjected to variable and impact load. in International Conference on New Trends in Fatigue and Fracture, 179-182.
https://hdl.handle.net/21.15107/rcub_machinery_6266

Sedmak S, Čamagić I, Sedmak A, Burzić Z, Đorđević B. The influence of the temperature and exploitation time on the behaviour of a welded joint subjected to variable and impact load. in International Conference on New Trends in Fatigue and Fracture. 2018;:179-182.
https://hdl.handle.net/21.15107/rcub_machinery_6266 .

Sedmak, Simon, Čamagić, I., Sedmak, Aleksandar, Burzić, Zijah, Đorđević, Branislav, "The influence of the temperature and exploitation time on the behaviour of a welded joint subjected to variable and impact load" in International Conference on New Trends in Fatigue and Fracture (2018):179-182,
https://hdl.handle.net/21.15107/rcub_machinery_6266 .

TY  - JOUR
AU  - Burzić, Meri
AU  - Sedmak, Stojan
AU  - Burzić, Zijah
AU  - Jaković, Dragan
AU  - Momčilović, Dejan B.
PY  - 2002
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/7549
AB  - Analiziran je uticaj sadržaja Mg u matrici i zapreminskog udela SiC čestica u metal matričnom kompozitu (MMC) na udarnu žilavost. Livena AlMg legura, sa 3%, 5% i 7% sadržaja Mg korišćena je kao metal matrice. Primenjen je sadržaj ojačavaća od 2%, 5% i 10%, sa prosečnom veličinom čestica od 30 µm. Kompozit je dobijen metodom vrtložnog livenja. Energija udara metal matričnog kompozita sa AlMg matricom smanjuje se sa porastom sadržaja SiC i smanjenjem sadržaja Mg. Najveća ukupna energija je nađena u MMC AlMg7 sa 2% SiC (14,7-17,5 J), a najmanja u MMC AlMg3 sa 10% SiC (3,7-4,1 J). Vrednosti za metal matrični kompozit su manje od vrednosti za odgovarajuću leguru za 40 do 50%.
AB  - The effect of Mg content in matrix and volume entail of SiC particles in metal matrix composite (MMC) on impact toughness is analyzed. Cast AlMg alloy, with 3%, 5% and 7% Mg content is used as metal matrix. Reinforcement content of 2%, 5% and 10%, with an average particle size of 30 µm, had been applied. Composite is obtained by whirlpool casting method. The impact energy of metal matrix composite with AlMg matrix decreases with increasing SiC content and with decreasing Mg content. The highest total energy is found in MMC AlMg7 with 2% SiC (14.7-17.5 J), and the lowest one in MMC AlMg3 with 10% SiC (3.7-4.1 J). The values for metal matrix composite are bellow that of corresponding alloy for 40 to 50% .
PB  - Institut za ispitivanje materijala, Beograd
T2  - Integritet i vek konstrukcija
T1  - Uticaj sadržaja ojačavača na udarnu žilavost livenog Al-SiCp metal matričnog kompozita
T1  - The effect of reinforcement content on impact toughness of cast Al-SiCP metal matrix composite
EP  - 14
IS  - 1-2
SP  - 11
VL  - 2
UR  - https://hdl.handle.net/21.15107/rcub_machinery_7549
ER  - 

@article{
author = "Burzić, Meri and Sedmak, Stojan and Burzić, Zijah and Jaković, Dragan and Momčilović, Dejan B.",
year = "2002",
abstract = "Analiziran je uticaj sadržaja Mg u matrici i zapreminskog udela SiC čestica u metal matričnom kompozitu (MMC) na udarnu žilavost. Livena AlMg legura, sa 3%, 5% i 7% sadržaja Mg korišćena je kao metal matrice. Primenjen je sadržaj ojačavaća od 2%, 5% i 10%, sa prosečnom veličinom čestica od 30 µm. Kompozit je dobijen metodom vrtložnog livenja. Energija udara metal matričnog kompozita sa AlMg matricom smanjuje se sa porastom sadržaja SiC i smanjenjem sadržaja Mg. Najveća ukupna energija je nađena u MMC AlMg7 sa 2% SiC (14,7-17,5 J), a najmanja u MMC AlMg3 sa 10% SiC (3,7-4,1 J). Vrednosti za metal matrični kompozit su manje od vrednosti za odgovarajuću leguru za 40 do 50%., The effect of Mg content in matrix and volume entail of SiC particles in metal matrix composite (MMC) on impact toughness is analyzed. Cast AlMg alloy, with 3%, 5% and 7% Mg content is used as metal matrix. Reinforcement content of 2%, 5% and 10%, with an average particle size of 30 µm, had been applied. Composite is obtained by whirlpool casting method. The impact energy of metal matrix composite with AlMg matrix decreases with increasing SiC content and with decreasing Mg content. The highest total energy is found in MMC AlMg7 with 2% SiC (14.7-17.5 J), and the lowest one in MMC AlMg3 with 10% SiC (3.7-4.1 J). The values for metal matrix composite are bellow that of corresponding alloy for 40 to 50% .",
publisher = "Institut za ispitivanje materijala, Beograd",
journal = "Integritet i vek konstrukcija",
title = "Uticaj sadržaja ojačavača na udarnu žilavost livenog Al-SiCp metal matričnog kompozita, The effect of reinforcement content on impact toughness of cast Al-SiCP metal matrix composite",
pages = "14-11",
number = "1-2",
volume = "2",
url = "https://hdl.handle.net/21.15107/rcub_machinery_7549"
}

Burzić, M., Sedmak, S., Burzić, Z., Jaković, D.,& Momčilović, D. B.. (2002). Uticaj sadržaja ojačavača na udarnu žilavost livenog Al-SiCp metal matričnog kompozita. in Integritet i vek konstrukcija
Institut za ispitivanje materijala, Beograd., 2(1-2), 11-14.
https://hdl.handle.net/21.15107/rcub_machinery_7549

Burzić M, Sedmak S, Burzić Z, Jaković D, Momčilović DB. Uticaj sadržaja ojačavača na udarnu žilavost livenog Al-SiCp metal matričnog kompozita. in Integritet i vek konstrukcija. 2002;2(1-2):11-14.
https://hdl.handle.net/21.15107/rcub_machinery_7549 .

Burzić, Meri, Sedmak, Stojan, Burzić, Zijah, Jaković, Dragan, Momčilović, Dejan B., "Uticaj sadržaja ojačavača na udarnu žilavost livenog Al-SiCp metal matričnog kompozita" in Integritet i vek konstrukcija, 2, no. 1-2 (2002):11-14,
https://hdl.handle.net/21.15107/rcub_machinery_7549 .

TY  - JOUR
AU  - Burzić, Meri
AU  - Sedmak, Stojan
AU  - Zrilić, Milorad
AU  - Burzić, Zijah
AU  - Jaković, Dragan
AU  - Momčilović, Dejan B.
PY  - 2002
UR  - https://machinery.mas.bg.ac.rs/handle/123456789/7547
AB  - Uticaj orijentacije ugljeničnih vlakana u kompozitu sa epoksi matricom na udarnu žilavost i na žilavost loma je eksperimentalno analiziran ispitivanjem Šarpi epruveta sa V zarezom i zarezanih epruveta modifikovanog CT oblika (sa oštrim vrhom zareza koji zamenjuje zamornu prslinu). Epruvete su proizvedene od uzoraka sa orijentacijom vlakana [±45]16s, [0/90]16s, kao i sa kombinovanim sastavom [02/90/±45/90/02]4s. Epruvete sa V zarezom su ispitivane na instrumentiranoj Šarpi mašini, čime je omogućeno razdvajanje energija nastanka i rasta prsline. Faktor intenziteta napona Kc je izabran kao parametar loma. Ukupne vrednosti udarne žilavosti su pokazale da [0/90]16s, kao što je očekivano, daje najveću otpornost na udar, ali su i vrednosti za [02/90/±45/90/02]4s bile zadovoljavajuće, sa pogodnim odnosom energije širenja i energije rasta prsline. Ispitivanje modifikovane CT epruvete je dalo slične i zadovoljavajuće rezultate za faktor intenziteta napona za dva uzorka ([0/90]16s i [02/90/±45/90/02]4s), dok je za treći [±45]16s, ova vrednost niža za oko 20%. Imajući na umu druge prednosti orijentacije [02/90/±45/90/02]4s, ona se može preporučiti kao najbolja uprkos nešto nižoj udarnoj energiji.
AB  - The effect of carbon fibers orientation in a composite with epoxy matrix on the impact and fracture toughness is experimentally analyzed by testing of Charpy type V notched specimens and notched specimens of modified CT form (with sharp notch tip as replacement for fatigue pre-crack). Specimens were produced from samples with carbon fiber orientation [±45]16s, [0/90]16s, and also with combined composition [02/90-/±45/90/-02]4s. Specimens with V notch have been tested on instrumented Charpy machine, enabling to separate crack initiation and propagation energies. Stress intensity factor Kc had been selected as fracture parameter. Total impact toughness values have shown that highest impact resistance belongs to [0/90]16s, as expected, but the values for [02/90/±45/90/02]4s are also satisfactory, with convenient ratio of crack propagation to crack initiation energies. Modified CT specimen testing have shown close and satisfactory results for stress intensity factor of two samples ([0/90]16s and [02/90/±45/90/02]4s), and for third sample [±45]16s this value is about 20% lower. Having in mind other benefits with [02/90/±45/90/0-2]4s, it can be recommended as superior in spite of somewhat lower impact energy.
PB  - Institut za ispitivanje materijala, Beograd
T2  - Integritet i vek konstrukcija
T1  - Uticaj orijentacije vlakana na udarnu žilavost i osobine loma kompozita ugljenična vlakna - epoksi smola
T1  - The effect of fiber orientation on impact toughness and fracture properties of carbon fiber-epoxy composite
EP  - 19
IS  - 1-2
SP  - 15
VL  - 2
UR  - https://hdl.handle.net/21.15107/rcub_machinery_7547
ER  - 

@article{
author = "Burzić, Meri and Sedmak, Stojan and Zrilić, Milorad and Burzić, Zijah and Jaković, Dragan and Momčilović, Dejan B.",
year = "2002",
abstract = "Uticaj orijentacije ugljeničnih vlakana u kompozitu sa epoksi matricom na udarnu žilavost i na žilavost loma je eksperimentalno analiziran ispitivanjem Šarpi epruveta sa V zarezom i zarezanih epruveta modifikovanog CT oblika (sa oštrim vrhom zareza koji zamenjuje zamornu prslinu). Epruvete su proizvedene od uzoraka sa orijentacijom vlakana [±45]16s, [0/90]16s, kao i sa kombinovanim sastavom [02/90/±45/90/02]4s. Epruvete sa V zarezom su ispitivane na instrumentiranoj Šarpi mašini, čime je omogućeno razdvajanje energija nastanka i rasta prsline. Faktor intenziteta napona Kc je izabran kao parametar loma. Ukupne vrednosti udarne žilavosti su pokazale da [0/90]16s, kao što je očekivano, daje najveću otpornost na udar, ali su i vrednosti za [02/90/±45/90/02]4s bile zadovoljavajuće, sa pogodnim odnosom energije širenja i energije rasta prsline. Ispitivanje modifikovane CT epruvete je dalo slične i zadovoljavajuće rezultate za faktor intenziteta napona za dva uzorka ([0/90]16s i [02/90/±45/90/02]4s), dok je za treći [±45]16s, ova vrednost niža za oko 20%. Imajući na umu druge prednosti orijentacije [02/90/±45/90/02]4s, ona se može preporučiti kao najbolja uprkos nešto nižoj udarnoj energiji., The effect of carbon fibers orientation in a composite with epoxy matrix on the impact and fracture toughness is experimentally analyzed by testing of Charpy type V notched specimens and notched specimens of modified CT form (with sharp notch tip as replacement for fatigue pre-crack). Specimens were produced from samples with carbon fiber orientation [±45]16s, [0/90]16s, and also with combined composition [02/90-/±45/90/-02]4s. Specimens with V notch have been tested on instrumented Charpy machine, enabling to separate crack initiation and propagation energies. Stress intensity factor Kc had been selected as fracture parameter. Total impact toughness values have shown that highest impact resistance belongs to [0/90]16s, as expected, but the values for [02/90/±45/90/02]4s are also satisfactory, with convenient ratio of crack propagation to crack initiation energies. Modified CT specimen testing have shown close and satisfactory results for stress intensity factor of two samples ([0/90]16s and [02/90/±45/90/02]4s), and for third sample [±45]16s this value is about 20% lower. Having in mind other benefits with [02/90/±45/90/0-2]4s, it can be recommended as superior in spite of somewhat lower impact energy.",
publisher = "Institut za ispitivanje materijala, Beograd",
journal = "Integritet i vek konstrukcija",
title = "Uticaj orijentacije vlakana na udarnu žilavost i osobine loma kompozita ugljenična vlakna - epoksi smola, The effect of fiber orientation on impact toughness and fracture properties of carbon fiber-epoxy composite",
pages = "19-15",
number = "1-2",
volume = "2",
url = "https://hdl.handle.net/21.15107/rcub_machinery_7547"
}

Burzić, M., Sedmak, S., Zrilić, M., Burzić, Z., Jaković, D.,& Momčilović, D. B.. (2002). Uticaj orijentacije vlakana na udarnu žilavost i osobine loma kompozita ugljenična vlakna - epoksi smola. in Integritet i vek konstrukcija
Institut za ispitivanje materijala, Beograd., 2(1-2), 15-19.
https://hdl.handle.net/21.15107/rcub_machinery_7547

Burzić M, Sedmak S, Zrilić M, Burzić Z, Jaković D, Momčilović DB. Uticaj orijentacije vlakana na udarnu žilavost i osobine loma kompozita ugljenična vlakna - epoksi smola. in Integritet i vek konstrukcija. 2002;2(1-2):15-19.
https://hdl.handle.net/21.15107/rcub_machinery_7547 .

Burzić, Meri, Sedmak, Stojan, Zrilić, Milorad, Burzić, Zijah, Jaković, Dragan, Momčilović, Dejan B., "Uticaj orijentacije vlakana na udarnu žilavost i osobine loma kompozita ugljenična vlakna - epoksi smola" in Integritet i vek konstrukcija, 2, no. 1-2 (2002):15-19,
https://hdl.handle.net/21.15107/rcub_machinery_7547 .