Slobodan Tabakovic - Academia.edu (original) (raw)

Papers by Slobodan Tabakovic

Research paper thumbnail of Analiza mogućnosti optimizacije putanje alata za pozicionu petoosnu obradu na CNC glodalicama

Zbornik radova Fakulteta tehničkih nauka u Novom Sadu, 2021

Rad predstavlja analizu mogućnosti optimizacije putanje alata na savremenim petoosnim obradnim ce... more Rad predstavlja analizu mogućnosti optimizacije putanje alata na savremenim petoosnim obradnim centrima za obradu glodanjem u SolidCAM softveru sa podrškom iMachining modula u cilju smanjenja obrade, optimalne upotrebe alata i materijala, a samim tim i puno novca.

Research paper thumbnail of Automatizovano programiranje numerički upravljanih mašina alatki za obradu glodanjem sa 4 i 5

U radu se opisuju postupci 5-osne obrade glodanjem primenom numerički upravljanih mašina alatki i... more U radu se opisuju postupci 5-osne obrade glodanjem primenom numerički upravljanih mašina alatki i njihov značaj (uloga) u savremenim proizvodnim tehnologijama. Ovoj tehnologiji pomažu, softverska rešenja i inovativni rezni alati koji podržavaju simultanu 5-osnu obradu.Obrada, kao i prethodni procesi izrade su definisani uz pomoć softverskog paketa SolidWorks-a i sa integrisanim softverom SolidCAM-a koji služi za pripremu programa obrade. Kao primer je u radu prikazana 5-osna obrada elemenata pokretnog dela turbinskog kola, koji se sastoji od kompleksnih površina.

Research paper thumbnail of Configuring a new educational machine tool based on hybrid kinematic mechanism

Tehnika, 2021

The paper shows the configuration of a new educational machine based on hybrid kinematics mechani... more The paper shows the configuration of a new educational machine based on hybrid kinematics mechanism. The concept of a three-axis O-X hybrid mechanism is described, consisting of a single serial translational axis and a two-axis parallel mechanism that can operate in two variants, with extended form O and crossed form X-joints of the parallel mechanism. The virtual prototype of the machine was configured in a CAD/CAM environment, where simulations of the mechanism's operation were performed. A programming system for machine has been prepared that also enables program verification. An open architecture control system based on the LinuxCNC platform has been configured for control of the machine. The trial work of the machine was performed in order to verify the realized prototype and control.

Research paper thumbnail of Methodology of Workspace Analysis of Machine Tools Based on Parallel Mechanisms Udc 621 . 91

The contemporary production using the processing method of removing materials has since recently ... more The contemporary production using the processing method of removing materials has since recently implied the application of new concepts of machine tools. Among them, the significant place belongs to parallel mechanism-based machine tools. The paper describes the methodology of analysis of parallel mechanisms' workspace aiming at establishing the basis for automated design of parallel mechanism-based machine tools.

Research paper thumbnail of Design of Custom Made Prosthesis of the Hip

Tehnicki vjesnik - Technical Gazette, 2019

Replacement of a natural hip joint with an artificial is one of the most commonly used surgical p... more Replacement of a natural hip joint with an artificial is one of the most commonly used surgical procedures in orthopaedic surgery. This paper describes the methodology of the hip joint prosthesis design, which presents the foundation for the automation of all stages of the development of custom-made prostheses. A general mathematical model based mostly on B-spline surfaces is used in order to define the prosthesis geometry. In order to verify the method, a software solution was developed and used for designing prostheses based on ten diagnostic images obtained by various methods. The results of the analysis of the ten designed prostheses, out of which five manufactured, show that deviations from the desired values are less than the errors caused by diagnostic imaging.

Research paper thumbnail of Determination of spatial position of tibial graft using x-ray images after anterior cruciate ligament reconstruction

Vojnosanitetski pregled

Background/Aim. Anterior cruciate ligament reconstruction is one of the most commonly performed k... more Background/Aim. Anterior cruciate ligament reconstruction is one of the most commonly performed knee surgeries in the younger population. The success of this procedure largely depends on the proper formation of the tunnel, which is obtained by drilling the tibia and which serves to position and fix the graft. Methods. The study was performed on a group of 15 patients in whom the developed software applied the measurement of the angle of the tunnel in the tibia based on the selection of characteristic points on two standard X-rays of the knee (anterior-posterior and lateral projection). The obtained results were compared with the results of measuring the angle of the tunnel in the tibia on knee images by computed tomography (CT) in all patients. Results. The drilling angle measured in CT scans is on average somewhat greater 59.07 ? 5.61? than the angle measured by applying a developed application 58.65 ? 5.89?. The obtained results indicate minimal differences without statistical sig...

Research paper thumbnail of Neural-Network-Based Approaches for Optimization of Machining Parameters Using Small Dataset

Materials, 2022

Surface quality is one of the most important indicators of the quality of machined parts. The ana... more Surface quality is one of the most important indicators of the quality of machined parts. The analytical method of defining the arithmetic mean roughness is not applied in practice due to its complexity and empirical models are applied only for certain values of machining parameters. This paper presents the design and development of artificial neural networks (ANNs) for the prediction of the arithmetic mean roughness, which is one of the most common surface roughness parameters. The dataset used for ANN development were obtained experimentally by machining AA7075 aluminum alloy under various machining conditions. With four factors, each having three levels, the full factorial design considers a total of 81 experiments that have to be carried out. Using input factor-level settings and adopting the Taguchi method, the experiments were reduced from 81 runs to 27 runs through an orthogonal design. In this study we aimed to check how reliable the results of artificial neural networks wer...

Research paper thumbnail of Methodology of Knee Bones Models 3D Printing Based on CT Series of Images

Machine Design, 2017

In this paper a methodology for knee bones models 3D printing from DICOM series of images is pres... more In this paper a methodology for knee bones models 3D printing from DICOM series of images is presented. It would be very useful for doctors to see real models of knee bones and ligament attachment sites onto both bones before the ACL reconstruction. With physical bone model, orientation and position of operative equipment (tibial and femoral guides) could be planned before the operation. This could lead to more precise ACL reconstruction. In the introductory part of this paper ACL reconstruction method and some problems that may occur are presented. After that, model of procedure for knee bones 3D printing is shown. First, a procedure for 3D knee bone models generation is shown. For this purpose a program system is developed based on the VTK library. Generation of femoral transverse axis which enables tibial bone to rotate about femoral bone is very important. This axis enables knee flexion and extension and in ACL reconstruction, doctors rotate tibial bone about femoral bone which is fixed. Point clouds of femoral bone condyles are used for calculation of centres of best fit spheres of both condyles by least squares method. After that bone models are prepared for 3D printing. Because of the MakerBot Replicator 2X printer limitations, model of the knee is printed in two parts which are then glued together.

Research paper thumbnail of Radni prostor O-X glide hibridnog mehanizma

posledica razvoja proizvoda, alata za obradu i procesa obrade, kao i zbog stalnog rasta zahteva t... more posledica razvoja proizvoda, alata za obradu i procesa obrade, kao i zbog stalnog rasta zahteva tržišta, pojavila se potreba za operacijama obrade koje se teško mogu izvesti na konvencionalno građenim mašinama alatkama. Primenom paralelnih mehanizama u gradnji mašina alatki razvijene su nove mašine koje mogu da ispune prethodne uslove. Međutim, paralelni mehanizmi nisu idealni za primenu u mašinama alatkama prvenstveno zbog radnog prostora koji je nepravilnog oblika. Njihovim kombinovanjem sa serijskim mehanizmima nastali su hibridni mehanizmi čiji je osnovni cilj iskorišćavanje najboljih karakteristika serijskih i paralelnih mehanizama, a da pri tome loše karkteristike oba mehanizma budu minimalne. U radu je prikazana matematička analiza radnog prostora hibridnog "O-X glide"mehanizma, i njegova verifikacija na prototipu mehanizma izrađenom metodom brze izrade prototipa. Hibridni mehanizam "O-X glide"je razvijen na Departmanu za proizvodno mašinstvo Fakulteta teh...

Research paper thumbnail of Računarsko modeliranje specijalne endoproteze "Spacer

Sadržaj—Maligna oboljenja medijalnog dela butne kosti (Femura), nadlaktice (Humerus), ili golenja... more Sadržaj—Maligna oboljenja medijalnog dela butne kosti (Femura), nadlaktice (Humerus), ili golenjače (Tibije), se leče hirurškim odstranjenjem dela obolelog koštanog tkiva i ugradnjom specijalne endoproteza "Spacer". Ovaj tip endoproteze se izrađuje iz dva dela (proksimalna i distalna komponenta) koji se povezuju vijčanom vezom. Konstrukcijom endoproteze se obezbeđuje antirotaciono svojstvo veze i omogućuje prenošenje opterećenja sa proksimalnog dela koštanog tkiva na distalni a da pri tome sami vijci koji obezbeđuju vezu nisu izloženi opterećenju. Za pravilno dimenzionisanje i implementaciju specijalne endoproteze neophodno je odrediti parametre koštane mase i oboljenja, a zatim i izraditi računarski model same endoproteze. Projektovanje specijalne endoproteze "Spacera" predstavlja kompleksnu proceduru baziranu na obradi dijagnostičkih snimaka (RTG, CT ili MR) pri čemu se primenom specijalizovanog softvera digitalizovani elementi slike pikseli prevode u voksele. ...

Research paper thumbnail of Automated Acquisition of Proximal Femur Morphological Characteristics

Measurement Science Review, 2014

The success of the hip arthroplasty surgery largely depends on the endoprosthesis adjustment to t... more The success of the hip arthroplasty surgery largely depends on the endoprosthesis adjustment to the patient's femur. This implies that the position of the femoral bone in relation to the pelvis is preserved and that the endoprosthesis position ensures its longevity. Dimensions and body shape of the hip joint endoprosthesis and its position after the surgery depend on a number of geometrical parameters of the patient's femur. One of the most suitable methods for determination of these parameters involves 3D reconstruction of femur, based on diagnostic images, and subsequent determination of the required geometric parameters. In this paper, software for automated determination of geometric parameters of the femur is presented. Detailed software development procedure for the purpose of faster and more efficient design of the hip endoprosthesis that ensures patients’ specific requirements is also offered

Research paper thumbnail of Computer and experimental analyses of the stress state in the cement hip joint endoprosthesis body

Vojnosanitetski pregled, 2014

Background/Aim. One of the possible complications after implantation of a cement hip-joint endopr... more Background/Aim. One of the possible complications after implantation of a cement hip-joint endoprosthesis is fracture in the endoprosthesis body. Fractures arise from overload or material fatigue of which an implant is made. The purpose of this research was to define the intensity of maximum stress and the positions of a critical cross-section in the endoprosthesis body. Methods. Unilaterally changing forces which act on the hip joint during walking as well as the loads result in flexible deformations of the endoprosthesis body. Biomechanical analysis of the forces acting on the hip joint determine their direction and intensity, whereas on the basis of Gruen?s classification of the endoprosthesis body loosening the level of fixation is established. The bodies of cement hip joint endoprosthesis are made of cobalt-chromiummolybdenum (CoCrMo) alloy, suitable for vacuum casting, are submitted to the analysis. Analysis of the critical stress in the endoprosthesis body was performed on th...

Research paper thumbnail of Mathematical modeling and experimental testing of high-speed spindle behavior

The International Journal of Advanced Manufacturing Technology, 2014

The prediction of thermo-mechanical behavior of the spindle is essential for machining precision.... more The prediction of thermo-mechanical behavior of the spindle is essential for machining precision. Particularly, the characteristics of high-speed spindles depend on their thermal behavior. The heat generated on the bearings transfers to the spindle and surrounding air, thus causing the thermal expansion of spindle elements. This paper presents the thermo-mechanical model of the spindle with ball bearings with angular contact. In this paper, the main source of heat on the spindle occurs due to friction torque on bearings with angular contact. The presented model is based on the mechanical model of the bearing and the numerical model (FEM) of the spindle. The proposed solution considers non-stationary change of temperature, thermal deformation, and bearing stiffness, based on the angular position of the ball. Predicting of bearing characteristics has been used to establish the change in static stiffness of the spindle nose as well as the effect of thermal expansion on the machining accuracy. In order to validate the model, experiments have been performed for different speeds. The paper establishes that the predicted temperatures on the spindle and spindle nose stiffness under different speeds correspond to those measured experimentally. The results of the experiment have shown that the increase of spindle speed causes the increase of bearing temperature, thus leading to the expansion of bearing elements. Additionally, these changes cause increased stiffness of the bearing, which in turn increases the stiffness of the spindle nose.

Research paper thumbnail of Designing special prosthesis "Spacer

Acta chirurgica iugoslavica, 2013

Malignant diseases of the medial part of the femur, humerus and tibia, treated with surgical remo... more Malignant diseases of the medial part of the femur, humerus and tibia, treated with surgical removal of the affected part of the bone and prosthesis fitting special "Spacer". This type of prosthesis is made in the form of the proximal and distal components that connect by screws. The design of endoprosthesis provides without possible rotation linear relationship and allows the transfer of load from the proximal to the distal bone, but the screws that provide connection are not exposed to stress. For proper sizing and implementation of a special prosthesis is necessary to determine the geometric parameters of bone mass and disease and then develop a computer model of the prosthesis. Designing a special prosthesis "spacer" is a complex procedure based on the processing of diagnostic images (X-ray, CT or MRI) with the use of specialized software digitized picture elements pixels translate into voxels. In this way a geometric model contains a form of external (KORTEX...

Research paper thumbnail of Program Suite for Conceptual Designing of Parallel Mechanism-Based Robots and Machine Tools

International Journal of Advanced Robotic Systems, 2013

In the development of robots and machine tools, in addition to conventional and serial structures... more In the development of robots and machine tools, in addition to conventional and serial structures, parallel mechanism-based kinematic structures have been used over a longer period of time. Aside from a number of advantages, the irregular shape and relatively small dimensions of the workspace formed by parallel mechanisms rank among the major weaknesses of their application. Accordingly, this fact has to be taken into consideration in the process of designing parallel mechanism-based robots or machine tools. This paper describes the categorization of criteria for the conceptual design of parallel mechanism-based robots or machine tools, resulting from workspace analysis as well as the procedure of their defining. Furthermore, it also presents the designing methodology that was implemented into the program for the creation of a robot or machine tool space model and the optimization of the resulting solution. For verification of the criteria and the programme suite, three common (conceptually different) mechanisms with a similar mechanical structure and kinematic characteristics were used.

Research paper thumbnail of Geometry, mechanical and ballistic properties of ADI material perforated plates

Materials & Design, 2015

Abstract In this paper, austempered ductile iron has been evaluated as an alternative to steel fo... more Abstract In this paper, austempered ductile iron has been evaluated as an alternative to steel for perforated plates applied in the ballistic protection of military vehicles. The austempering was performed in lower and higher austempering ranges in order to obtain two types of austempered ductile iron: one with a higher strength, and the other with a higher ductility. Perforated plates having two different thicknesses of 7 and 9 mm were mounted in front of basic armour and 12.7 × 99 mm armour – piercing incendiary ammunition was fired from 100 m. It was shown that the austempered ductile iron material austempered at a lower temperature has superior ballistic resistance, providing a full (five out of five armour – piercing incendiary shots stopped) ballistic resistance if combined with 13 mm basic armour plate. The thicker austempered ductile iron perforated plate provides more significant penetrating core damage, and therefore, lower basic plate damage. On the other hand, the thinner austempered ductile iron material perforated plate can be considered optimal due to its lower weight and higher mass effectiveness. In austempered ductile iron material austempered at a higher temperature, besides a lower hardness, bulk retained low-carbon metastable austenite transforms into martensite through strain induced mechanism, causing a partial brittle fracture.

Research paper thumbnail of Modelling and analysis of machine tool with parallel–serial kinematics based on O-X glide mechanism

Journal of the Brazilian Society of Mechanical Sciences and Engineering

Research paper thumbnail of A study of thermal behavior of the machine tool spindle

Thermal Science

The performances of high-speed machine tools depend not only on the speed, power, torque, dynamic... more The performances of high-speed machine tools depend not only on the speed, power, torque, dynamic and static stiffness, but also on the thermal behavior of the spindle. These parameters directly affect the productivity and quality of machining operations. This paper presents a 3-D finite element thermal model, which was based on the thermo mechanical bearing model and the numerical model of the spindle. Based on thermo mechanical analysis of bearings with angular contact, generated heat and thermal contact resistance are determined for each position of the ball. To provide the most accurate analysis possible in determining thermal contact resistance , bearings are divided into several zones based on the geometry of their cross-section. The aforementioned constraints have been applied to the 3-D FEM model which allowed for establishing temperature field distribution, and spindle thermal balance. In order to prove the efficacy of the proposed model, experimental measurements of spindl...

Research paper thumbnail of General Parametric Model of The Body of The Total Hip Endoprosthesis

Acta Polytechnica Hungarica

The endoprostheses of the hip joint are the most commonly used group of implants in orthopedic su... more The endoprostheses of the hip joint are the most commonly used group of implants in orthopedic surgery. The success of their application in the process of replacing natural hip joint with artificial depends, besides the patient related and surgical factors, which include the selection of the type of endoprosthesis and the extent of its adaptability to the patient. Because of that, endoprostheses adapted to the patient's measures, so-called custom made endprostheses, are used. The main challenge in their design is large number of influential factors on the shape and dimensions of the endoprosthesis, the long period of development, and high prices as a consequence of these factors. One of the directions of endoprosthesis design process improvement is the introduction of generalized computational models that enable the adaptation of the endoprosthesis to a specific patient's femur, taking into consideration all influential factors of the disease. This paper describes a general parametric model of the body of the hip endoprosthesis, which was developed by combining two methods of parametric modeling with the aim to implement all existing contributing factors and, also, facilitate introduction of the new ones. The main advantages of this model of endoprosthesis are: flexibility and simplicity which makes this model easy for application in a variety of CAD software systems.

Research paper thumbnail of The tibial aperture surface analysis in anterior cruciate ligament reconstruction process

Medicinski pregled, 2016

Introduction. The tibial tunnel aperture in the anterior cruciate ligament reconstruction is usua... more Introduction. The tibial tunnel aperture in the anterior cruciate ligament reconstruction is usually analyzed as an ellipse, generated as an intersection between a tibial plateau and a tibial bone tunnel. The aim of this study is to show that the tibial tunnel aperture, which utilizes 3D tibial surface bone model, differs significantly from common computations which present the tibial tunnel anterior cruciate ligament aperture surface as an ellipse. Material and Methods. An interactive program system was developed for the tibial tunnel aperture analysis which included the real tibia 3D surface bone model generated from a series of computed tomography images of ten male patients, their mean age being 25 years. In aperture calculation, the transverse drill angle of 10o was used, whereas sagittal drill angles of 40o, 50o and 60o were used with the drill-bit diameter set to 10 mm. The real 3D and 2D tibial tunnel aperture surface projection was calculated and compared with an ellipse. R...

Research paper thumbnail of Analiza mogućnosti optimizacije putanje alata za pozicionu petoosnu obradu na CNC glodalicama

Zbornik radova Fakulteta tehničkih nauka u Novom Sadu, 2021

Rad predstavlja analizu mogućnosti optimizacije putanje alata na savremenim petoosnim obradnim ce... more Rad predstavlja analizu mogućnosti optimizacije putanje alata na savremenim petoosnim obradnim centrima za obradu glodanjem u SolidCAM softveru sa podrškom iMachining modula u cilju smanjenja obrade, optimalne upotrebe alata i materijala, a samim tim i puno novca.

Research paper thumbnail of Automatizovano programiranje numerički upravljanih mašina alatki za obradu glodanjem sa 4 i 5

U radu se opisuju postupci 5-osne obrade glodanjem primenom numerički upravljanih mašina alatki i... more U radu se opisuju postupci 5-osne obrade glodanjem primenom numerički upravljanih mašina alatki i njihov značaj (uloga) u savremenim proizvodnim tehnologijama. Ovoj tehnologiji pomažu, softverska rešenja i inovativni rezni alati koji podržavaju simultanu 5-osnu obradu.Obrada, kao i prethodni procesi izrade su definisani uz pomoć softverskog paketa SolidWorks-a i sa integrisanim softverom SolidCAM-a koji služi za pripremu programa obrade. Kao primer je u radu prikazana 5-osna obrada elemenata pokretnog dela turbinskog kola, koji se sastoji od kompleksnih površina.

Research paper thumbnail of Configuring a new educational machine tool based on hybrid kinematic mechanism

Tehnika, 2021

The paper shows the configuration of a new educational machine based on hybrid kinematics mechani... more The paper shows the configuration of a new educational machine based on hybrid kinematics mechanism. The concept of a three-axis O-X hybrid mechanism is described, consisting of a single serial translational axis and a two-axis parallel mechanism that can operate in two variants, with extended form O and crossed form X-joints of the parallel mechanism. The virtual prototype of the machine was configured in a CAD/CAM environment, where simulations of the mechanism's operation were performed. A programming system for machine has been prepared that also enables program verification. An open architecture control system based on the LinuxCNC platform has been configured for control of the machine. The trial work of the machine was performed in order to verify the realized prototype and control.

Research paper thumbnail of Methodology of Workspace Analysis of Machine Tools Based on Parallel Mechanisms Udc 621 . 91

The contemporary production using the processing method of removing materials has since recently ... more The contemporary production using the processing method of removing materials has since recently implied the application of new concepts of machine tools. Among them, the significant place belongs to parallel mechanism-based machine tools. The paper describes the methodology of analysis of parallel mechanisms' workspace aiming at establishing the basis for automated design of parallel mechanism-based machine tools.

Research paper thumbnail of Design of Custom Made Prosthesis of the Hip

Tehnicki vjesnik - Technical Gazette, 2019

Replacement of a natural hip joint with an artificial is one of the most commonly used surgical p... more Replacement of a natural hip joint with an artificial is one of the most commonly used surgical procedures in orthopaedic surgery. This paper describes the methodology of the hip joint prosthesis design, which presents the foundation for the automation of all stages of the development of custom-made prostheses. A general mathematical model based mostly on B-spline surfaces is used in order to define the prosthesis geometry. In order to verify the method, a software solution was developed and used for designing prostheses based on ten diagnostic images obtained by various methods. The results of the analysis of the ten designed prostheses, out of which five manufactured, show that deviations from the desired values are less than the errors caused by diagnostic imaging.

Research paper thumbnail of Determination of spatial position of tibial graft using x-ray images after anterior cruciate ligament reconstruction

Vojnosanitetski pregled

Background/Aim. Anterior cruciate ligament reconstruction is one of the most commonly performed k... more Background/Aim. Anterior cruciate ligament reconstruction is one of the most commonly performed knee surgeries in the younger population. The success of this procedure largely depends on the proper formation of the tunnel, which is obtained by drilling the tibia and which serves to position and fix the graft. Methods. The study was performed on a group of 15 patients in whom the developed software applied the measurement of the angle of the tunnel in the tibia based on the selection of characteristic points on two standard X-rays of the knee (anterior-posterior and lateral projection). The obtained results were compared with the results of measuring the angle of the tunnel in the tibia on knee images by computed tomography (CT) in all patients. Results. The drilling angle measured in CT scans is on average somewhat greater 59.07 ? 5.61? than the angle measured by applying a developed application 58.65 ? 5.89?. The obtained results indicate minimal differences without statistical sig...

Research paper thumbnail of Neural-Network-Based Approaches for Optimization of Machining Parameters Using Small Dataset

Materials, 2022

Surface quality is one of the most important indicators of the quality of machined parts. The ana... more Surface quality is one of the most important indicators of the quality of machined parts. The analytical method of defining the arithmetic mean roughness is not applied in practice due to its complexity and empirical models are applied only for certain values of machining parameters. This paper presents the design and development of artificial neural networks (ANNs) for the prediction of the arithmetic mean roughness, which is one of the most common surface roughness parameters. The dataset used for ANN development were obtained experimentally by machining AA7075 aluminum alloy under various machining conditions. With four factors, each having three levels, the full factorial design considers a total of 81 experiments that have to be carried out. Using input factor-level settings and adopting the Taguchi method, the experiments were reduced from 81 runs to 27 runs through an orthogonal design. In this study we aimed to check how reliable the results of artificial neural networks wer...

Research paper thumbnail of Methodology of Knee Bones Models 3D Printing Based on CT Series of Images

Machine Design, 2017

In this paper a methodology for knee bones models 3D printing from DICOM series of images is pres... more In this paper a methodology for knee bones models 3D printing from DICOM series of images is presented. It would be very useful for doctors to see real models of knee bones and ligament attachment sites onto both bones before the ACL reconstruction. With physical bone model, orientation and position of operative equipment (tibial and femoral guides) could be planned before the operation. This could lead to more precise ACL reconstruction. In the introductory part of this paper ACL reconstruction method and some problems that may occur are presented. After that, model of procedure for knee bones 3D printing is shown. First, a procedure for 3D knee bone models generation is shown. For this purpose a program system is developed based on the VTK library. Generation of femoral transverse axis which enables tibial bone to rotate about femoral bone is very important. This axis enables knee flexion and extension and in ACL reconstruction, doctors rotate tibial bone about femoral bone which is fixed. Point clouds of femoral bone condyles are used for calculation of centres of best fit spheres of both condyles by least squares method. After that bone models are prepared for 3D printing. Because of the MakerBot Replicator 2X printer limitations, model of the knee is printed in two parts which are then glued together.

Research paper thumbnail of Radni prostor O-X glide hibridnog mehanizma

posledica razvoja proizvoda, alata za obradu i procesa obrade, kao i zbog stalnog rasta zahteva t... more posledica razvoja proizvoda, alata za obradu i procesa obrade, kao i zbog stalnog rasta zahteva tržišta, pojavila se potreba za operacijama obrade koje se teško mogu izvesti na konvencionalno građenim mašinama alatkama. Primenom paralelnih mehanizama u gradnji mašina alatki razvijene su nove mašine koje mogu da ispune prethodne uslove. Međutim, paralelni mehanizmi nisu idealni za primenu u mašinama alatkama prvenstveno zbog radnog prostora koji je nepravilnog oblika. Njihovim kombinovanjem sa serijskim mehanizmima nastali su hibridni mehanizmi čiji je osnovni cilj iskorišćavanje najboljih karakteristika serijskih i paralelnih mehanizama, a da pri tome loše karkteristike oba mehanizma budu minimalne. U radu je prikazana matematička analiza radnog prostora hibridnog "O-X glide"mehanizma, i njegova verifikacija na prototipu mehanizma izrađenom metodom brze izrade prototipa. Hibridni mehanizam "O-X glide"je razvijen na Departmanu za proizvodno mašinstvo Fakulteta teh...

Research paper thumbnail of Računarsko modeliranje specijalne endoproteze "Spacer

Sadržaj—Maligna oboljenja medijalnog dela butne kosti (Femura), nadlaktice (Humerus), ili golenja... more Sadržaj—Maligna oboljenja medijalnog dela butne kosti (Femura), nadlaktice (Humerus), ili golenjače (Tibije), se leče hirurškim odstranjenjem dela obolelog koštanog tkiva i ugradnjom specijalne endoproteza "Spacer". Ovaj tip endoproteze se izrađuje iz dva dela (proksimalna i distalna komponenta) koji se povezuju vijčanom vezom. Konstrukcijom endoproteze se obezbeđuje antirotaciono svojstvo veze i omogućuje prenošenje opterećenja sa proksimalnog dela koštanog tkiva na distalni a da pri tome sami vijci koji obezbeđuju vezu nisu izloženi opterećenju. Za pravilno dimenzionisanje i implementaciju specijalne endoproteze neophodno je odrediti parametre koštane mase i oboljenja, a zatim i izraditi računarski model same endoproteze. Projektovanje specijalne endoproteze "Spacera" predstavlja kompleksnu proceduru baziranu na obradi dijagnostičkih snimaka (RTG, CT ili MR) pri čemu se primenom specijalizovanog softvera digitalizovani elementi slike pikseli prevode u voksele. ...

Research paper thumbnail of Automated Acquisition of Proximal Femur Morphological Characteristics

Measurement Science Review, 2014

The success of the hip arthroplasty surgery largely depends on the endoprosthesis adjustment to t... more The success of the hip arthroplasty surgery largely depends on the endoprosthesis adjustment to the patient's femur. This implies that the position of the femoral bone in relation to the pelvis is preserved and that the endoprosthesis position ensures its longevity. Dimensions and body shape of the hip joint endoprosthesis and its position after the surgery depend on a number of geometrical parameters of the patient's femur. One of the most suitable methods for determination of these parameters involves 3D reconstruction of femur, based on diagnostic images, and subsequent determination of the required geometric parameters. In this paper, software for automated determination of geometric parameters of the femur is presented. Detailed software development procedure for the purpose of faster and more efficient design of the hip endoprosthesis that ensures patients’ specific requirements is also offered

Research paper thumbnail of Computer and experimental analyses of the stress state in the cement hip joint endoprosthesis body

Vojnosanitetski pregled, 2014

Background/Aim. One of the possible complications after implantation of a cement hip-joint endopr... more Background/Aim. One of the possible complications after implantation of a cement hip-joint endoprosthesis is fracture in the endoprosthesis body. Fractures arise from overload or material fatigue of which an implant is made. The purpose of this research was to define the intensity of maximum stress and the positions of a critical cross-section in the endoprosthesis body. Methods. Unilaterally changing forces which act on the hip joint during walking as well as the loads result in flexible deformations of the endoprosthesis body. Biomechanical analysis of the forces acting on the hip joint determine their direction and intensity, whereas on the basis of Gruen?s classification of the endoprosthesis body loosening the level of fixation is established. The bodies of cement hip joint endoprosthesis are made of cobalt-chromiummolybdenum (CoCrMo) alloy, suitable for vacuum casting, are submitted to the analysis. Analysis of the critical stress in the endoprosthesis body was performed on th...

Research paper thumbnail of Mathematical modeling and experimental testing of high-speed spindle behavior

The International Journal of Advanced Manufacturing Technology, 2014

The prediction of thermo-mechanical behavior of the spindle is essential for machining precision.... more The prediction of thermo-mechanical behavior of the spindle is essential for machining precision. Particularly, the characteristics of high-speed spindles depend on their thermal behavior. The heat generated on the bearings transfers to the spindle and surrounding air, thus causing the thermal expansion of spindle elements. This paper presents the thermo-mechanical model of the spindle with ball bearings with angular contact. In this paper, the main source of heat on the spindle occurs due to friction torque on bearings with angular contact. The presented model is based on the mechanical model of the bearing and the numerical model (FEM) of the spindle. The proposed solution considers non-stationary change of temperature, thermal deformation, and bearing stiffness, based on the angular position of the ball. Predicting of bearing characteristics has been used to establish the change in static stiffness of the spindle nose as well as the effect of thermal expansion on the machining accuracy. In order to validate the model, experiments have been performed for different speeds. The paper establishes that the predicted temperatures on the spindle and spindle nose stiffness under different speeds correspond to those measured experimentally. The results of the experiment have shown that the increase of spindle speed causes the increase of bearing temperature, thus leading to the expansion of bearing elements. Additionally, these changes cause increased stiffness of the bearing, which in turn increases the stiffness of the spindle nose.

Research paper thumbnail of Designing special prosthesis "Spacer

Acta chirurgica iugoslavica, 2013

Malignant diseases of the medial part of the femur, humerus and tibia, treated with surgical remo... more Malignant diseases of the medial part of the femur, humerus and tibia, treated with surgical removal of the affected part of the bone and prosthesis fitting special "Spacer". This type of prosthesis is made in the form of the proximal and distal components that connect by screws. The design of endoprosthesis provides without possible rotation linear relationship and allows the transfer of load from the proximal to the distal bone, but the screws that provide connection are not exposed to stress. For proper sizing and implementation of a special prosthesis is necessary to determine the geometric parameters of bone mass and disease and then develop a computer model of the prosthesis. Designing a special prosthesis "spacer" is a complex procedure based on the processing of diagnostic images (X-ray, CT or MRI) with the use of specialized software digitized picture elements pixels translate into voxels. In this way a geometric model contains a form of external (KORTEX...

Research paper thumbnail of Program Suite for Conceptual Designing of Parallel Mechanism-Based Robots and Machine Tools

International Journal of Advanced Robotic Systems, 2013

In the development of robots and machine tools, in addition to conventional and serial structures... more In the development of robots and machine tools, in addition to conventional and serial structures, parallel mechanism-based kinematic structures have been used over a longer period of time. Aside from a number of advantages, the irregular shape and relatively small dimensions of the workspace formed by parallel mechanisms rank among the major weaknesses of their application. Accordingly, this fact has to be taken into consideration in the process of designing parallel mechanism-based robots or machine tools. This paper describes the categorization of criteria for the conceptual design of parallel mechanism-based robots or machine tools, resulting from workspace analysis as well as the procedure of their defining. Furthermore, it also presents the designing methodology that was implemented into the program for the creation of a robot or machine tool space model and the optimization of the resulting solution. For verification of the criteria and the programme suite, three common (conceptually different) mechanisms with a similar mechanical structure and kinematic characteristics were used.

Research paper thumbnail of Geometry, mechanical and ballistic properties of ADI material perforated plates

Materials & Design, 2015

Abstract In this paper, austempered ductile iron has been evaluated as an alternative to steel fo... more Abstract In this paper, austempered ductile iron has been evaluated as an alternative to steel for perforated plates applied in the ballistic protection of military vehicles. The austempering was performed in lower and higher austempering ranges in order to obtain two types of austempered ductile iron: one with a higher strength, and the other with a higher ductility. Perforated plates having two different thicknesses of 7 and 9 mm were mounted in front of basic armour and 12.7 × 99 mm armour – piercing incendiary ammunition was fired from 100 m. It was shown that the austempered ductile iron material austempered at a lower temperature has superior ballistic resistance, providing a full (five out of five armour – piercing incendiary shots stopped) ballistic resistance if combined with 13 mm basic armour plate. The thicker austempered ductile iron perforated plate provides more significant penetrating core damage, and therefore, lower basic plate damage. On the other hand, the thinner austempered ductile iron material perforated plate can be considered optimal due to its lower weight and higher mass effectiveness. In austempered ductile iron material austempered at a higher temperature, besides a lower hardness, bulk retained low-carbon metastable austenite transforms into martensite through strain induced mechanism, causing a partial brittle fracture.

Research paper thumbnail of Modelling and analysis of machine tool with parallel–serial kinematics based on O-X glide mechanism

Journal of the Brazilian Society of Mechanical Sciences and Engineering

Research paper thumbnail of A study of thermal behavior of the machine tool spindle

Thermal Science

The performances of high-speed machine tools depend not only on the speed, power, torque, dynamic... more The performances of high-speed machine tools depend not only on the speed, power, torque, dynamic and static stiffness, but also on the thermal behavior of the spindle. These parameters directly affect the productivity and quality of machining operations. This paper presents a 3-D finite element thermal model, which was based on the thermo mechanical bearing model and the numerical model of the spindle. Based on thermo mechanical analysis of bearings with angular contact, generated heat and thermal contact resistance are determined for each position of the ball. To provide the most accurate analysis possible in determining thermal contact resistance , bearings are divided into several zones based on the geometry of their cross-section. The aforementioned constraints have been applied to the 3-D FEM model which allowed for establishing temperature field distribution, and spindle thermal balance. In order to prove the efficacy of the proposed model, experimental measurements of spindl...

Research paper thumbnail of General Parametric Model of The Body of The Total Hip Endoprosthesis

Acta Polytechnica Hungarica

The endoprostheses of the hip joint are the most commonly used group of implants in orthopedic su... more The endoprostheses of the hip joint are the most commonly used group of implants in orthopedic surgery. The success of their application in the process of replacing natural hip joint with artificial depends, besides the patient related and surgical factors, which include the selection of the type of endoprosthesis and the extent of its adaptability to the patient. Because of that, endoprostheses adapted to the patient's measures, so-called custom made endprostheses, are used. The main challenge in their design is large number of influential factors on the shape and dimensions of the endoprosthesis, the long period of development, and high prices as a consequence of these factors. One of the directions of endoprosthesis design process improvement is the introduction of generalized computational models that enable the adaptation of the endoprosthesis to a specific patient's femur, taking into consideration all influential factors of the disease. This paper describes a general parametric model of the body of the hip endoprosthesis, which was developed by combining two methods of parametric modeling with the aim to implement all existing contributing factors and, also, facilitate introduction of the new ones. The main advantages of this model of endoprosthesis are: flexibility and simplicity which makes this model easy for application in a variety of CAD software systems.

Research paper thumbnail of The tibial aperture surface analysis in anterior cruciate ligament reconstruction process

Medicinski pregled, 2016

Introduction. The tibial tunnel aperture in the anterior cruciate ligament reconstruction is usua... more Introduction. The tibial tunnel aperture in the anterior cruciate ligament reconstruction is usually analyzed as an ellipse, generated as an intersection between a tibial plateau and a tibial bone tunnel. The aim of this study is to show that the tibial tunnel aperture, which utilizes 3D tibial surface bone model, differs significantly from common computations which present the tibial tunnel anterior cruciate ligament aperture surface as an ellipse. Material and Methods. An interactive program system was developed for the tibial tunnel aperture analysis which included the real tibia 3D surface bone model generated from a series of computed tomography images of ten male patients, their mean age being 25 years. In aperture calculation, the transverse drill angle of 10o was used, whereas sagittal drill angles of 40o, 50o and 60o were used with the drill-bit diameter set to 10 mm. The real 3D and 2D tibial tunnel aperture surface projection was calculated and compared with an ellipse. R...