The route to J-integral by prof. James Rice

Professor James Rice, world-leading expert in the field of mechanics, recently visited the Faculty of Mechanical Engineering in Belgrade, where he held a heavily attended lecture devoted to the 50th anniversary of his paper about the J-integral. The lecture was a part of the international fracture mechanics Summer School, an event that accompanied the 22nd European Conference on Fracture which is currently taking place at the “Metropol” hotel.

James rice is a professor of engineering sciences and geophysics at the Harvard University in the USA. Fifty years ago he formulated one of the most important fracture mechanics parameters, the so-called J-integral, which is defined as one of the means for calculating of the change in fracture surface strain energy, which is of great significance in structural integrity assessment. During his lecture, Professor Rice also mentioned some of the applications of the J-integral, which was particularly important to some of the Summer School participants.

The concept of the J-integral is indubitably one the most important scientific contributions of prof. Rice. During the last few decades, his research was focused on the subjects in the field of geomechanics – glaciers, earthquakes and other important aspects of fracture, which he specifically spoke of in his introductory lesson at the opening of the 22nd European Conference on Fracture.

After the previous conferences held in Trondheim and Catania, this year’s Summer School took place on 25th and 26th of August in Belgrade. It was organised by the Structural Integrity and Life Society “Prof. dr Stojan Sedmak”, in cooperation with the Faculty of Mechanical Engineering in Belgrade.

The Summer School was attended by around 150 participants. Young researchers, engineers and PhD students from all over the world had the opportunity to learn about the latest research results in the field of fracture mechanics, by listening to lectures held by world-leading experts.

Prof. John Landes from the USA spoke about the topic of “Basics of experimental fracture mechanics, linear elastic and elastic-plastic growth”. The lecture held by prof. Francesco Iacoviello from the Cassina University in Italy was about the “Basics of experimental fracture mechanics, fatigue crack growth”. Prof. Bamber Blackman from the Imperial College in London spoke about the deforming and failure of polymers and composites, whereas the subject of interface fracture mechanics was covered by prof. Leslie Banks-Sills from the Tel Aviv University in Israel.

The first international fracture mechanics Summer School, known as “The Introduction to Fracture Mechanics and fracture-safe design was organised in 1980 by the Faculty of Technology and Metallurgy and the GOŠA Institute, under the initiative of prof. Michael Wnuk (Wisconsin University, Milwaukee) and prof. Stojan Sedmak (Faculty of Technology and Metallurgy, Belgrade). The Summer School was attended by a total of 63 participants, and 20 lectures were held, one of which was an invited lecture.

ECF 22 – Global scientific elite in Belgrade

The problems of fracture mechanics and structural integrity were the central topic of the 22. European Conference on Fracture, which takes place in Belgrade, from 27th to 31st of August this year. More than 500 participants from all over the world will consider the most important aspects of this field of mechanics, which studies problems related to cracks and their effects on the behaviour of materials and structures. The conference was organised by the Structural Integrity and Life Society “Prof. dr Stojan Sedmak”, in cooperation with the European Structural Integrity Society (ESIS).

This conference on fracture, the first to be held in Serbia after 26 years, was officially opened on Monday, August 27th at the Metropol Hotel in Belgrade. The conference opening was attended by the representative of relevant ministries within the Government of the Republic of Serbia, as well as the representatives of the University of Belgrade, the scientific and industrial community and many other respected guests from our country and abroad.

On behalf of the Ministry of education, science and technological development of Republic of Serbia, the guests were greeted by the State Secretary, prof. dr Viktor Nedović, who took the opportunity to point out the importance of this conference not only for Serbia, but also for the region as a whole. On behalf of the Faculty of Mechanical Engineering of University of Belgrade, the guests were greeted by prof. dr Nenad Zrnić, the newly elected rector for international scientific cooperation of the University of Belgrade, and the vice-dean of international cooperation at the Faculty of Mechanical Engineering. The guests were also addressed by the conference chairman, prof. dr Aleksandar Sedmak, who is also the president of the Structural Integrity and Life Society “Prof. dr Stojan Sedmak”, and prof. dr Leslie Banks-Sills, the president of ESIS.

The work section of the conference was opened by a lecture held by prof. dr James Rice, a world-leading expert who formulated one the most important parameters in fracture mechanics, the J-Integral, 50 years ago. Prof. Rice teaches engineering sciences and geophysics at the Harvard University, and has been involved in geomechanical studies (glaciers, earthquakes…) for the past few decades. His lecture on this subject attracted major attention from the conference participants.

The first day of the conference was marked by two additional lectures. Prof. dr Jovo Jarić, a Serbian representative, spoke about the topic of “Conservation laws of the J Integral type”, whereas his colleague from Croatia, prof. dr Dražan Kozak held a lecture titled “Integrity of the pipeline by using the pipe-ring testing, part 1”.

On the second day, the plenary lectures were held by prof. dr Yoshi Hong from China, on the topic of “The State of the Art in Very-High-Cycle Fatigue Research”, professor Uwe Zerbst on the topic of “Application of fracture mechanics to S-N curve prediction”, professor Meinhard Kuna on the topic of “Micromechanical modeling of fracture in metallic materials”, and professor Nenad Gubeljak from Slovenia, who presented a lecture named “Integrity of pipeline by using pipe-ring testing, Part 2”.

The latest results and scientific breakthroughs in the field of fracture mechanics and structural integrity will be the focus of the conference in the following days. “Soft Network Composite Materials with Deterministic and Bio-Inspired Designs” was the subject of a lecture held by prof. Yonggang Huang from the USA. His compatriot, prof. Robert Ritchie will speak about the “Damage tolerance in Biological and Metallic Materials”. The subject that will be presented by prof. William Curtin from Switzerland is “Mechanisms of Hydrogen Embrittlement: Insights from Atomistic Studies”, whereas prof. Takayuki Kitamura from Japana will speak about the “Challenge toward Nanometer Scale Fracture Mechanics”.

Mini-symposia involving the fracture mechanics topics which are currently of most interest, above all related to hydrogen embrittlement, which represents the most significant problem related to corrosion failure, will be organised as a part of the conference.

The organisation of the 22nd European Conference on Fracture was financially supported by the Ministry of education, science and technological development of Republic of Serbia, EPS and other sponsors (Rumul, Messer and Sobriety), and significant support was provided by the Faculty of Mechanical Engineering of University of Belgrade, which co-organised the Summer School of fracture mechanics.

 

Nemanja Gligorijevic – A student and an entrepreneur

Nemanja Gligorijević

Nemanja Gligorijević is a student of the final year of master studies at the Production Engineering department of the Faculty of Mechanical Engineering. However, he already has his own small-size company which produces 3D printers and provides 3D printing services. “It was my desire to confirm in practice the degree of a mechanical engineer and the knowledge obtained at the faculty. Hence, I designed and manufactured several models of 3D printers. In June last year, together with my sister, I founded the start-up company Highbreed Systems and we are currently the only 3D printer producers in Serbia”, says Nemanja.

The Faculty of Mechanical Engineering has a yearlong tradition of an educational institution which encourages the students to be innovative and trains them not only to solve the real engineering tasks, but also to develop completely new products. Therefore, Nemanja is the best example how a young man who is innovative can start manufacturing the new, so-called intelligent products and successfully place them on the market.

Nemanja is especially proud of his new project, the printer with the dimensions of 500x500x500.

 

This is the biggest 3D printer in the region and it is primarily intended for industrial purposes. “We cooperate with a number of companies, both in Serbia and abroad. These are mostly tool-producing companies for which we manufacture part prototypes that are obtained by injection moulding. Still, the project that is dearest to me personally is the lining for a prosthetic leg made for a young Serbian kayak athlete, one of the Olympic team members. It was an honour to produce it, and I was pleased to learn that the lining had actually served as an incentive for the further development of an idea to start up a company in the field of prosthetics”, says Nemanja.

“However, without the knowledge obtained at the FME, I would not be able to achieve all these results. The Faculty gave me knowledge which was transferred into my products and into my own company as well. Naturally, I am also greatly indebted to my parents, who supported me in founding the Highbreed Systems”, says Nemanja in the end.

(Source: Faculty of Mechanical Engineering)

 

The J21 Jastreb – The custodian of the tradition of aeronautical engineering

The J-21 Jastreb (Hawk), the first domestic fighting aircraft which was serially produced in the former Yugoslavia, has been recently placed on the plateau in front of the Aeronautical Technical Institute of the Faculty of Mechanical Engineering in Belgrade. The aircraft is positioned on a six-metre high pedestal in slight ascent, which creates an impression that it is really flying and draws the attention of passers-by on daily basis.

The J-21 Jastreb is training and fighting aircraft designed at the Aeronautical Technical Institute with great participation of the Department of Aeronautical Engineering of the Faculty of Mechanical Engineering, says Dr Časlav Mitrović, the Head of the Department, which has recently celebrated eight decades of educating aeronautical engineers in Serbia. The J-21 Jastreb is a gift of the Ministry of Defence of the Republic of Serbia and the Aeronautical Museum. It will be at students’ disposal as a teaching aid which would serve to practically introduce the most vital aircraft parts. The aircraft was transported to the Aeronautical Technical Institute in parts. Students participated both in the disassembly and assembly of aircraft parts, and are currently working on repairing the aircraft engine, which will also serve as an exhibit and a teaching aid.

The J-21 Jastreb was a Yugoslav single-seat, single-engine, light attack aircraft, intended for surveillance and fire. It is most definitely the best proof of the expertise and craftsmanship of the aeronautical engineers trained at the Department of Aeronautical Engineering of the Faculty of Mechanical Engineering. The J-21 Jastreb was derived from the advanced jet trainer and light attack aircraft, the G-2 Galeb, and presented to the world at the Farnborough air show in 1968. It could carry weapons in the fuselage and non-guided bombs and rockets in the underwing pylons, which meant it could also handle ground attacks. Besides Yugoslavia, it was used in Libya and Zambia. In the period from 1985 to 1990 seven Jastreb planes were part of the acrobatic air team The Flying Stars.

The J-21 Jastreb was officially revealed on 22nd December 2017, the day of marking the 80th anniversary of the date when regular classes started at the Aeronautical Group of the Technical Faculty in Belgrade in 1937.

(Source: Faculty of Mechanical Engineering)

 

CLEAN-kWAT project – Achieving the balance between energy systems and the environment

Фото: pixabay.com

The first results of the international CLEAN-kWAT project, in which the Faculty of Mechanical Engineering is a participant, have been recently presented at the 48th International Congress on Heating, Refrigeration and Air-Conditioning held in Belgrade. The basic aim of the project is to support the system of education of young engineers in the energy supply sector. The idea is to develop innovative materials which would help integrate environmental considerations into energy systems development. Some of the most important project results include developing training materials for young engineers, the e-learning portal and videos.

The participants of the Erasmus+ KA2 CLEAN-kWAT project are eight reputable scientific institutions, companies and NGOs from Turkey, Germany, Serbia, Spain and Hungary. The project is funded with support from the Turkish National Agency. The Faculty of Mechanical Engineering is implementing the project on behalf of the University of Belgrade.

Since global warming is a direct result of the fossil fuel use, there are increasing efforts in Europe aimed towards defining an institutional and legislative framework for the development of energy systems that would be designed in keeping with the demands for environmental protection and preservation of natural resources, says Aleksandra Sretenović, Assistant Professor at the FME and the Head of the CLEAN-kWAT project. Therefore, special attention should be devoted to education, especially in the energy departments, which, unfortunately, in many universities still do not have sufficient number of obligatory courses related to the field of preservation of the environment.

The aim of the European Qualification Framework (EQF) is to make National Qualification (NQF) understandable in Europe, which would allow better mobility of workers between countries and the development of a common educational system.

The CLEAN-kWAT project will address precisely these issues, says Dr Sretenović. It will point to the required skills and competences for working in the energy supply sector through the development of the new learning outcomes and the improvement of the existing ones, as well as through the redefinition of the necessary competence standards. Based upon this, training modules will be developed and available at the e-learning platform. The main target group of the project includes energy systems designers and engineering students in the departments of energy systems engineering.

(Source: Faculty of Mechanical Engineering)

The DualEdu Project – Domestic needs, foreign experiences and the best model for Serbia

The DualEdu Erasmus+ project, aimed at the implementation of dual education in higher education in Serbia, has been recently presented at the first kick-off meeting of the project team at the Faculty of Mechanical Engineering. The project brings together 14 permanent partners from Serbia, Germany, Austria, France, Spain and Poland. It started on 15th October 2017 and is scheduled to last over the next three years.

The basic idea is to make a dual education model in the system of higher education that would be general enough, but also flexible, and which could be implemented depending on the needs of higher education institutions, says professor Nenad Zrnić, Vice-Dean for international scientific cooperation at the FME. The development of the expert system is due to start in the first year of the project, and, based on the input and output parameters, this system should make it possible to define the needs and the preferred outcome of dual education, he says. This stage should be followed by the pilot project that would be implemented in several study programmes, i.e. by several institutions, which should enable an insight into the functioning of dual education in practice.

Besides the University of Belgrade, i.e. the Faculty of Mechanical Engineering which manages the whole project and work package, project participants include the Metropolitan University, University of Kragujevac, University of Novi Sad and the School of Electrical and Computer Engineering of Applied Studies. The partners from France will manage the work package that includes the experiences in dual education of the EU member countries, while the Austrian project team will manage the work package for quality testing. The project also features 13 associate members/companies, which would make it possible for students to attend dual education. These companies would be the actual beneficiaries of project results in practice. At present, these are mostly IT companies, but it is expected that a number of other companies from the field of machine industry will be included, as well as other companies whose work encompasses the areas in which the mechanical engineering students, as well as the students of other faculties, are educated.

(Source: Faculty of Mechanical Engineering)

Students of the Industrial Engineering module – Winners of the Bosch week

Danijela Živanović, Ivana Knežević, Miloš Perić, Alen Alidini and Dragomir Zec are the members of the team of students from the Industrial Engineering module that provided the best solution to the case study at the competition held as a part of the week of the Robert Bosch Company. These talented young people proudly say that this competition was a wonderful opportunity to demonstrate in practice the high quality of education of engineers at the Faculty of Mechanical Engineering.

Four student teams participated in solving the case study, formed of students attending different modules of the FME – industrial engineering, production engineering, food industry engineering and thermal power engineering. Each team was tasked with providing the best solution to the problem of mixing the types of connectors at the HS workstation. The students of the module of Industrial Engineering won.

Having performed a detailed analysis of the entire production process, the Industrial Engineering module team suggested two methods – the four eyes principle, which envisages two operators that perform control on one product, and the Poka Yoke method, which is designed to prevent human error using a pattern. The Poka Yoke method is somewhat slower compared to the four eyes principle, but reduces the error to the utmost minimum. The solution which contains two alternatives was very appealing to the jury, but they were wondering which alternative would be a better solution if it were necessary to choose only one. This was answered in the following way: the final choice of the method depends on the company’s priorities, i.e. whether they insisted on quality or quantity.

The Robert Bosch Company offers an opportunity to the members of the winning team to become interns at their company and, possibly, their employees.

(Source: Faculty of Mechanical Engineering)

Robots and platforms from the laboratory of the Faculty of Mechanical Engineering

The moving platform for realistic flight and driving simulators, developed by Professor Dragan Milutinović, is only one in the vast array of current projects of the researchers at the Industrial Robotics and Artificial Intelligence Laboratory of the Faculty of Mechanical Engineering. The cutting-edge platform is intended for making simulators for various kinds of vehicles, such as aircraft, armoured personnel carriers or construction machinery, says Professor Milutinović, who is also the Head of the Laboratory.

The device, which has captured the attention of both the domestic and international manufacturers, is the outcome of twenty years of work on the modelling of parallel kinematic machines (robots, machine tools and simulators). One of the most important results achieved during this research is the development of the methods for modelling the parallel kinematic mechanisms based on a minimum number of parameters.

This has enabled us to perform the complete modelling of the platform based on parallel mechanics with 6 degrees of freedom and the powered rotary joints, serving as the basis for the development of the realistic flight and driving simulators. This is what makes it possible for the platform to function in real time, says Professor Milutinović. Realistic simulators are very complex mechatronics systems which include a visual module, a moving platform and a haptic module (the Washout algorithm), so that the perception of kinematic and dynamic effects is encompassed.

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He spent two years working on the model on his own, and then spent the next several months performing detailed computer simulations together with his associates. This had produced fruitful results and there was a need to test the model experimentally by developing and constructing the moving platform prototype.

It is interesting to note that one of the fastest robotic and machine tool platforms in the world was actually developed from the platform originally developed for flight simulators.

 

(Source: Faculty of Mechanical Engineering)

 

The Road Arrow Team – The pride of the Faculty of Mechanical Engineering and the University of Belgrade

Eight years ago, a group of students of the Faculty of Mechanical Engineering gathered around an amazing idea and managed to form the team that would represent Serbia at Formula Student, the most prestigious engineering students’ competition in the world. Owing to students’ commitment and great support, the Road Arrow team has become a recognisable brand and the pride of both the Faculty of Mechanical Engineering and University of Belgrade.

The task of the members of the team is to design and construct a racing car, which then competes at racing tracks throughout Europe with 600 university teams from around the world. Six vehicles were made starting from 2012, and the team competed in races all around Europe (Germany, Great Britain, Italy, Hungary, Austria etc.).

The project encourages students to think creatively and apply an innovative approach to solving all the demands they are facing. A valuable experience for students is working with older colleagues, some of whom are already employed at the companies that very much appreciated the knowledge they had acquired during their participation in the Road Arrow team activities.

Today, the team includes more than 50 students from eight faculties of the University of Belgrade. There are six subteams: aerodynamics and design, chassis and handling, powertrain, materials, electronics, and marketing and sponsorships. The design is a very demanding process, since the students need to design a safe, reliable and agile racing car. On the other hand, this is an opportunity for both Bachelor and Master students to join in and broaden the knowledge obtained at the faculty. Apart from design, throughout the season, the students work on construction and testing, and attend competitions. All the time, the team needs good organisation, fund raising and project management. That is why being a member of the Road Arrow resembles being employed at a company, and this is what distinguishes the members of this team from other students.

The design of the vehicle for the current season has already been completed. The team is now working on manufacturing all the necessary parts in order to be able to start assembling the Road Arrow 2018 in spring. This stage will be followed by performing various tests and preparing for competitions. The goal for this season is to construct a reliable vehicle which would be successful at competitions. All the pieces of information about the progress of the team are available at www.stt.org.rs, as well as on social networks. The video footage can be found on the You Tube channel Drumska Strela – Road Arrow Belgrade.

 

(Source: Faculty of Mechanical Engineering)