September 25, 2017

Doctoral thesis defence – K. Marković

Our member D. Sc. Kristina Marković defended her doctoral thesis entitled “ANALYSIS OF INFLUENCING PARAMETERS IN THE DESIGN OF CROSS – SPRING PIVOTS” on March 20th, 2015.

Doctoral thesis supervisor vas Prof. D. Sc. Saša Zelenika.

Committee for the defense of the doctoral thesis:
  1. Prof. D. Sc.Dubravka Siminiati, University of Rijeka, Croatia, Faculty of Engineering (Sveučilište u Rijeci, Tehnički fakultet) – Committee Chair
  2. Prof. D. Sc. Saša Zelenika, University of Rijeka, Croatia, Faculty of Engineering (Sveučilište u Rijeci, Tehnički fakultet)
  3. Prof. D. Sc. Nenad D. Pavlović, University of Niš, Serbia, Faculty of Mechanical Engineering (Mašinski fakultet Univerziteta u Nišu)

Thesis abstract:

Compliant mechanisms, that gain at least part of their mobility from the deflection of flexible members, are an alternative to conventional sliding and rolling mechanisms used to transfer motion, power or force. Compliant mechanisms are nowadays widely used in mechanical engineering design, precision engi neering as well as the micro- and nanosystems technologies. Parameters influencing the design of differ ent configurations of cross-spring pivots are analysed in this doctoral thesis. In fact, the main goals in their design are: achieving the highest possible accuracy and precision, achieving the lowest possible variability of rotational stiffness, stability, design simplicity and reliability. Since the considered mechanis ms are constituted by spring-strips, the prediction of their behaviour is to be based on the analysis of the characteristic parameters of the strips themselves. In order to analyse the influencing parameters in the design of symmetrical cross-spring pivots loaded by a pure couple, an analytical model of the behaviour of spring-strips in the field of large (geometrically nonlinear) deflections based on the Elastica method, as well as a numerical model based on the finite elements method, are hence developed in the thesis. In order to assess the applicability of the developed numerical model in predicting the stress-strain behaviour of the considered mechanisms, results obtained numer ically are compared with experimental data available in literature. With the goal of determining the limits of applicability of the approximated calculation methods depending on the needed accuracy, the results of the analytical calculations of the stress-strain behaviour of the cross-spring pivots are then compared with results obtained by using the finite element method. Numerical calculations are used next to optimise pivots’ design by assessing the influence of the angle and the position of the intersection as well as of the initial curvature of the spring-strips,. A design solution allowing the minimisation of the parasitic shifts, as well as the minimisation of variability of the rotational stiffness, even for large rotations of the pivot is thus obtained. At the end of the thesis, ananalysis of the influence of external loads on the variability of rotational stiffness and on the entity of the parasitic shifts is also performed. The results obtained in the doctoral thesis allow thus not only assessing the influence of the design parameters in the design of cross-spring pivots (i.e. the influence of these parameters on rotational stiffness and the accuracy of the considered mechanisms), but also creating the preconditions for the development of a new class of ultra-high precision rotational compliant mechanisms with potentially broad applications in industrial and design praxis.
     

Collaboration with School of Medicine in Rijeka

Update (09-13-2014):

As a result of collaborative research between School of Medicine in Rijeka and Precision Engineering Laboratory of Faculty of Engineering in Rijeka,  an article has been published in The Korean Journal of Orthodonics and can be read here.

Colaboration with School of Medicine in Rijeka

The Precision Engineering Laboratory has established cooperation with the School of Medicine in Rijeka. Measurement of special screws with small dimensions which are used in orthodontics was conducted using the Optical Stereomicroscope Olympus SZX16.

Characteristic properties (size, pitch angle etc.) of the screws were measured since the manufacturer does not provide this information in their catalogs for this type of special screws. Measurements were carried out in order to further analyze the influence of the dimensions of the screws on the percentage of successful operations on patients.

Measurements and analysis were performed and the final report was made in March 2012. We wish to thank Prof. Stjepan Špalj and Prof. Barbara Mady Maričić from the School of Medicine in Rijeka, Chair of Pediatric Dentistry and Orthodontics for cooperation with the Precision Engineering Laboratory.

Also, we wish to thank to our students: Arian Karabegović, Jelena Srnec and Dražen Žužić for their assistance during the measurements.

 

Doctoral thesis defence – D. Blažević

Our member D. Sc. David Blažević defended his doctoral thesis entitled “Analysis of mechanical aspects in the design of vibration energy harvesters” on September 2nd, 2014.

Doctoral thesis supervisor vas Prof. D. Sc. Saša Zelenika.

Committee for the defense of the doctoral thesis:
  1. Prof. D. Sc. Dubravka Siminiati, University of Rijeka, Croatia, Faculty of Engineering (Sveučilište u Rijeci, Tehnički fakultet) – Committee Chair
  2. Prof. D. Sc. Saša Zelenika, University of Rijeka, Croatia, Faculty of Engineering (Sveučilište u Rijeci, Tehnički fakultet)
  3. Prof. D. Sc. Nenad D. Pavlović, University of Niš, Serbia, Faculty of Mechanical Engineering (Mašinski fakultet Univerziteta u Nišu)

Thesis abstract:

The process of collecting low level ambient energy and its conversion into electric energy is commonly termed energy harvesting or energy scavenging. The thesis has as its main goal to develop and experimentally validate numerical models of piezoelectric energy harvesting devices. In order to maximise output power, different configurations and eigenfrequency bands are taken into account. The developed experimental set-up, used to classify the proposed devices, is explained in detail together with a patented solution for future use in automobile pneumatics.

    

14th international science conference EUSPEN 2014, Dubrovnik

Employees of the Precision Engineering Laboratory visited the 14th international science conference EUSPEN 2014, held from 02. to 06.06.2014. in Dubrovnik. The conference is run and organized by the European society for precision engineering and nanotechnology. It’s an international conference, visited by scientists and engineers from all over the world. The main science themes are:

  • Renewable Energy Technologies
  • Precision Engineering for Medical Products
  • Additive Manufacturing for Precision Engineering
  • Nano & Micro Metrology
  • Ultra Precision Machines
  • Ultra Precision Manufacturing & Assembly Processes
  • Important/Novel Advances in Precision Engineering & Nano Technologies
  • Motion Control in Precision Systems, Nano & Micro Manufacturing

In the theme Renewable Energy Technologies our team presented a poster:

  • River flow energy harvesting by employing piezoelectric eels‘, by authors: E. Kamenar, S. Zelenika, D. Blažević and student I Šamanić. Paper can be read here, poser can be found here.

In the theme Ultra Precision Machines, our team presented two posters:

  • Precision positioning system with high-speed FPGA-based closed loop control‘ by authors E. Kamenar, S. Zelenika and M. Franulović. Paper can be read here, poser can be found here.
  • Numerical modelling of piezoelectric vibration energy scavenging bimorphs‘ by authors D. Blažević and S. Zelenika. Paper can be read here, poser can be found here.

euspen logo colourx2

Award for the best student paper on the 37th MIPRO conference

Employees of the Precision Engineering Laboratory participated on the 37th International Convention on Information and CommunicationTechnology, Electronics and Microelectronics (MIPRO) in Opatija, Croatia.

In the SP MIPRO Junior Student Papers section our team presented a work entitled ‘Comparison of different DC motor positioning control algorithms’, written by students  Nikola Baćac, Vedran Slukić, Miroslav Puškarić, Boris Štih, junior researcher Ervin Kamenar and professor Saša Zelenika.

The paper won the award for the best student paper!

The paper can be read here, and pptx presentation can be seen here.

2014mipro

Precision engineering laboratory team accepted the prize for “SAV” inovation

David Blažević, Ervin Kamenar and Saša Zelenika accepted the prize for the inovation named “Self regulating autonomus valve – SAV” from Primorsko-goranska county of the Republic of Croatia.
More details can be found here and here (in Croatian language).

12-inovatori

EUSPEN Challenge 2013

David Blažević and Ervin Kamenar, Croatian national heat winners, participated at the Euspen Challenge event which was held in Copenhagen from 2nd till 4th July 2013, at the Otticon headquartes, and Technical University of Copenhagen. Otticon is one of the biggest producers of cutting edge hearing aids in the world.

Euspen Challenge is an international competition to identify outstanding students across Europe with potential to be future leaders in the field of precision engineering and Nanotechnology. It is a unique opportunity for young engineers to promote themselves at an international level  and to connect with industry.

This year’s Euspen Challenge involved 9 International teams of 3 students.

The main challenge was to develop and construct a prototype of an auxiliary tool for battery loading of small hearing aids. As hearing aids get smaller, grabbing and changing batteries becomes a serious problem mainly for elderly people. In that case an interface is needed. Production as well as impact considerations on economic welfare were integral parts of the challenge exercise.

David’s team won the award for the best presentation.

euspen

The displacement analysis of CNC machine “Prvomajska TU360”

In a collaboration with prof. Zoran Jurković from the Department of industrial engineering and management, positioning accuracy and repeatability of the X axis of the CNC machine “Prvomajska TU360” were experimentally assessed. A Michelson-type laser Doppler interferometric system was employed to complete the assessment. Several different linear positioning experiments were conducted. In the first two experiments, positioning with a 5 mm step is performed for the 200 mm measuring range of the X axis. The measurements are repeated for the 20 and 40 mm steps in the same positioning range. The team is currently working on the analyses of the obtained data.

36th International Convention on Information and CommunicationTechnology, Electronics and Microelectronics (MIPRO)

Employees of the Precision Engineering Laboratory participated the 36th International Convention on Information and CommunicationTechnology, Electronics and Microelectronics (MIPRO) held from May 20th till May 24th in Opatija, Croatia.

The main science fields on the conference are:

  • MEET – Microelectronics, Electronics and Electronic Technology
  • DC VIS – Distributed Computing and Visualization
  • CTI – Telecommunications & Information
  • CE – Computers in Education
  • CTS – Computers in Technical Systems
  • CIS – Intelligent Systems
  • ISS – Information Systems Security
  • miproBIS – Business Intelligence Systems
  • DE – Digital Economy – 10th ALADIN
  • GLGPS – Government, Local Government, Public Services
  • SP – MIPRO Junior – Student Papers

In the first theme our team presented a work entitled ‘Micropositioning mechatronics system based on FPGA architecture’, which can be read here, and which pptx presentation can be seen here.

mipro

SPIE Microtechnologies Conference 2013

Employees of the Precision Engineering Laboratory visited the SPIE Microtechnologies conference held from April 24th till April 26th in Grenoble, France. The SPIE Microtechnologies is the premier European meeting for the latest research in microtechnologies, from bio-engineered and bio-inspired systems to developments in photonic materials, devices, and applications. It’s an international conference visited by the scientists and engineers from all over the world. The main science fields are: Smart Sensors, Actuators, and MEMS VI, VLSI Circuits and Systems VI, Bio-MEMS and Medical Microdevices, Nanotechnology VI and Integrated Photonics: Materials, Devices, and Applications II. In the first theme our team presented a poster entitled ‘Load optimised piezoelectric generator for powering battery-less TPMS’, which can be read here, and which poster can be seen here.

Article about WATPS in Croatian journal “Auto klub”

Article about Original solution for Wireless Autonomous Tire Pressure Sensor (WATPS), was published in Croatian journal “Auto klub” on Semptember, 14th, 2012.
Complete article (Croatian language) in printed edition can be found on the following link:

Auto klub

12th international science conference EUSPEN 2012

Employees of the Precision Engineering Laboratory visited the 12th international science conference EUSPEN 2012, held from 04. to 08.06.2012. in Stockholm. The conference is run and organized by the European society for precision engineering and nanotechnology. It’s an international conference, visited by scientists and engineers from all over the world. The main science themes are: Precision Engineering of Plastic based Electronics and Optronics, Nordic Countries Precision Engineering and Nanotechnology, Nano & Micro Metrology, Ultra Precision Machines & Control, High Precision Mechatronics, Ultra Precision Manufacturing & Assembly Processes, Important/Novel Advances in Precision Engineering & Nano Technologies. In the last theme our team presented a poster entitled ‘Vibration energy scavenging powered wireless tire pressure monitoring sensor’, which can be read here.

Article about WATPS in Croatian journal “Glas Istre”

Article about Original solution for Wireless Autonomous Tire Pressure Sensor (WATPS) and Precision engineering laboratory activities, was published in Croatian journal “Glas Istre” on July, 27th, 2012.
Complete article, in printed edition, in Croatian language, can be found  on the following link:

Razvili bežični senzor za tlak u gumama kojem ne treba baterija

New FP7 projects have been published

A new calls for FP7 projects have been published. Precision Engineering Laboratory members are planning to apply for chapter II.2.2. NMP.2013.2.2-4 – Materials solutions for durable energy-harvesters. Partners from industry and universities which are interested to collaborate with our team are welcome to contact us via this link.

Article about WATPS in Croatian journal “Novi list”

Article about Original solution for Wireless Autonomous Tire Pressure Sensor (WATPS) and Precision engineering laboratory activities, was published in Croatian journal “Novi list” on July, 9th, 2012.
Complete article, in Croatian language, can be found  on the following link:

Razvili bežični autonomni senzor tlaka kojem ne treba baterija

Complete article in printed edition:

Click here