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Energijska metoda, naziva drugi Castiglianov teorem, predstavlja neobičan, pouzdan i često iznenađujuće jednostavan pristup analiziranju pomaka i rotacija na konstrukciji. Metoda se pokazala iznimno korisnom kod analize reakcija u osloncima konstrukcija koje su jednostruko statički neodređene. Cilj rada je pokazati da se primjenom drugog Castiglianovog teorema, izraza za deformaciju aksijalno opterećenog štapa te metode iteracije mogu analizirati momentni okvirni nosači s jednim dodanim aksijalno opterećenim štapom. Nosač zadan na ovakav način dvostruko je statički neodređen. Analiza prikazana u radu sadrži pomake i rotacije karakterističnih točaka nosača, reakcije u osloncima te von Misesovo ekvivalentno naprezanje u gredama. Identična analiza napravljena je i metodom konačnih elemenata te su na kraju uspoređeni rezultati dviju metoda.

Popravak motora je svakodnevni problem u automobilskim servisima. Zbog složenosti motora često su njihove proporcije poput mase i dimenzija vrlo velike. Kako bi se olakšao pristup svim dijelovima motora prilikom sklapanja izrađen je nosač. Morfološkom matricom su izrađene četiri varijante nosača motora koje su vrednovane AHP metodom. Radom je prikazana konstrukcijska izvedba nosača u opterećenom stanju kako bi prikazali numeričku analizu i utvrdili da su naprezanja zavara u dopuštenim granicama.

This paper presents the application of the Analytic Hierarchy Process (AHP) method in the process of evaluating of conceptual variants at the conceptual stage. Using the requirement list and the morphological matrix, three conceptual variants of supporting structures were created for placing traffic signs. With the AHP method, the conceptual variants (alternatives) were compared. Then a set of six criteria was defined according to which the conceptual variants were evaluated. A variant with the highest weight factor, is also the chosen design solution that will be formed as a final product in the phase of detailed design.

–The paper presents a descriptive Matrix of function and functionality (MFF) that was created to improve the Morphological matrix. The main idea was to develop a matrix that uses mathematical laws to connect functions and function solutions. Therefore, rules are defined that uniquely describe functions by using a system of parameters. Functionalities represent technical systems, which lead to mutual relations with functions. Solutions of the required functions make sub-matrices that connect functions and functionalities. MFF represents a design tool used in the conceptual phase. This tool contributes to the unambiguous management of the design process. Functional requirements is possible to divide into categories, such as shape requirements, load requirements, kinematic requirements, maintenance requirements, etc. Since functions represent transformed requirements, the MFF is a tool that enables them to be solve in conceptual and product maintenance phase. In such a way, in the early phases of product lifecycle is possible by MFF, to set functional requirements for the exploration, maintenance and product recycling.

This paper presents joining of material, usually of grey cast iron, by the metalock and masterlock joining methods. There is a complete joining procedure presented, which includes metalock keys and masterlock plate. Examples of successful applications of these two methods of material joining are presented within demanding reparation processes. The paper also elaborates comparison of tensile test carried out by using metalock repair method and welding on grey cast iron SL 25.

This paper presents joining of material, usually of grey cast iron, by the metalock and masterlock joining methods. There is a complete joining procedure presented, which includes metalock keys and masterlock plate. Examples of successful applications of these two methods of material joining are presented within demanding reparation processes. The paper also elaborates comparison of tensile test carried out by using metalock repair method and welding on grey cast iron SL 25.

In recent biomechanical testing of soft tissues, many researchers have presented the usage of different clamping techniques such as using frozen clamps, non-frozen serrated jaw clamps, a non-frozen clamp which has lateral block boards and asymmetrical teeth yaws to prevent tissues from slipping and without damaging it at high loads. In this study, for future biomechanical testing of human gracilis and quadriceps tendons, we present the usage of a 3D printing approach as a possibility for making clamps. We took the measures of the existing pneumatic jaw clamps on Shimadzu AGS-X 10 kN machine and according to the measurements, we have designed and 3D print the clamps which have different geometry inspired by the cross-sectional view of metric, trapezoidal and buttress thread, to act as extensions to existing ones and to be able to prevent tendon slipping and damaging during compression. Based on the tensile tests using porcine tendons, we report our experience. It has been shown that we can avoid expensive changes in existing equipment, buying commercially available plastic and metal materials and manufacturing it or else use frozen clamps which are complex and expensive. We have shown that using a low-cost 3D printer and cheap polyethylene terephthalate glycol (PET-G) material can lead to successful scientific work. To our knowledge, by searching available literature, there is only one similar study published during writing this paper.

The article gives a subject review of recent investment to research and development (R&D) in Republic of Croatia related to other world countries, paying special attention to STEM field. It analyzes current number of the students and graduates at higher education institutions in Croatia with refer to EU and world. There is a lack of all technical professions, including ICT. Employability of the graduates in STEM field is in increasing in economically developed countries what could be the sign to decision makers in Croatia what kind of study programs should be promoted. There is one of the key-questions how to stop the brain drain of the experts in STEM field out from Croatia due to the fact that average salary in EU developed countries is even three times more. Is in that case unconditional free higher education investment to the development of other countries, indeed? Croatia stands very bad regarding the number of researchers per million inhabitants and also by investment to R&D. These data are looking still worse in its structure, where 80% of money allocated from public sector for education and R&D is spending for salaries of employees. Investments to R&D from business sector are also relatively small, in particular if they are compared to those in developed countries. This paper is trying to find out is there any correlation between defended doctoral thesis and economic development in Croatian counties, and also between study programs profile and export. It analyzes the influence of investment to R&D on the economic recovering and draw a parallel between current study programs in Croatia and its innovativeness level. There are given particularly some comments regarding the students quota to the study programs in STEM field related to others, that are approximately in the ratio 40:60. At the end of work some examples of good practice are given and steps taken so far to fix the today's situation in direction of economic recovering of Republic of Croatia.

Prema Pravilniku o ukapljenom naftnom plinu (UNP), skladištenje plinskih boca odvija se, u pravilu, na otvorenom prostoru. Budući da se taj skladišni prostor u većini slučajeva nalazi pored postaja za opskrbu prijevoznih sredstava gorivom pri čemu sigurnosna udaljenost skladišta boca do bilo kojeg mogućeg stalnog izvora paljenja iznosi 5 metara, uvijek postoji potencijalna opasnost od eksplozije. Kako bi se vidjelo kako materijal boca podnosi eksploziju, u radu je simuliran utjecaj udara zračnog vala pri čemu je za analizu korištena čelična plinska boca kapaciteta punjenja do 10kg. 3D model boce izrađen je u SolidWorksu prema normi 10 HRN M.Z2.510, a potom je provedena numerička analiza u Abaqusu. Inicijacija eksplozije postavljena je na različitim udaljenostima od boce počevši od predviđenih 5 metara i bliže. Za modeliranje eksplozije korištena su punjenja od 10 kg, 50kg i 100 kg TNT-a.

The paper describes mechanical testing on specimens made from 13CrMo4-5 boiler steel and numerical analysis based on conducted experiment. During magnetic particle testing (MT) examination of weld on the bottom header of a front wall of boiler large amount of indications (cracks) were noticed. In the experimental part of paper tension test was conducted in order to determine basic mechanical properties of specimens. After that, bend testing was conducted to determine an angle on which cracks occur, and ultimately fracture. In order to compare obtained results with results obtained experimentally, 3D model of specimens was created, and numerical analysis by finite element method (FEM)was carried out. Analysis of results has given guidance for further examinations, assuming that they will ultimately give an answer on type an incurred cracks.

U radu je opisan pristup određivanja debljine kutnog zavara na primjeru spajanja stope i glavine kliznog ležaja. Za zadano pogonsko opterećenje analitički je izračunata potrebna debljina zavarenog spoja, koja je metodom konačnih elemenata provjerena pomoću programa ANSYS Workbench. U konačnici, određen je postotak pogonskog opterećenja koje zavar može podnijeti tako da naprezanje bude u dopuštenim granicama. Ovisnost veličine najvećeg naprezanja o kutu radijalne pogonske sile prikazana je dijagramom.

The basic requirement which is placed in front of modern thermal power plants is higher degree of utilization rates. As one of possible way of fulfilling the requirement is to increase steam parameters, which is conditioned by application of materials suitable for work on default temperatures and pressures. Materials used in steam boiler production must fulfill quality requirements, which are defined according to terms of exploitation which will be exposed during his lifespan, but also should be appropriate for the manufacturing process. At the same time, with the development of of boiler power plants, development of materials to be installed in boilers has run also. As one of significant representative of materials in boiler power production is also heat resistant low alloy steel 13CrMo4 - 5. Aim of this paper was to present and analyze main causes which led to the occurence and propagation of crack on bottom header front wall of crack. After conducted experiments type of cracks is determined, and after detailed analysis causes of cracks.

According to the Ordinance on liquefied petroleum gas (LPG), the storage of gas cylinders is usually carried out in the open space. Since this storage space is in most cases located next to the fuel supply station whereby the safety distance of the bottle storage to any possible permanent ignition source is 5 meters, there is always a potential risk of explosion. In order to show how the material of the gas cylinders behaves at the explosion, the impact of the air blast was simulated. The gas cylinder used for the analysis was a capacity of up to 10 kg. The 3D model of the gas cylinder was made in SolidWorks according to 10 HRN MZ2.510 regulative and numerical analysis was made in Abaqus and in Ls-Dyna. The initiation of the explosion is set at different distances from the gas cylinder starting from the 5 meters and closer, and also it is time-dependent. For the explosion model, 10 kg, 50 kg and 100 kg of TNT charging were used.

Konstrukcijska izvedba ručne dizalice sadrži podizač tereta zavaren na maticu koja se pomjera po navojnom vretenu. Za predviđenu nosivost proračunom zavarenog spoja utvrđuje se da li su sva naprezanja u dopuštenim granicama te se određuje potrebna debljina zavara. Proračun je proveden za dvije različite konstrukcijske izvedbe pri jednakoj vrijednosti opterećenja, te je provedena numerička analiza. Na temelju toga utvrđeno je koje konstrukcijsko rješenje matice sa zavarenim podizačem bolje zadovoljava zadano opterećenje.

A widely known fact is that the wish for higher profit in all human activities tends to be often related to highly negative influences to the environment. However, there are some examples where the wish to obtain higher profits, and the continual market competition result in positive environment influ-ences. These positive influences are a result of one of the basic profit increase method – cost reduction by process efficiency optimisation. For freight railroad transportation, every unnecessarily transported own weight kilogram is a direct cost. One example of transport cost reduction is a reduction of freight wagon tare weight, without disturbing other wagon characteristics. With tare weight reduction, comes the increase in useful payload of the wagon, since the total weight (tare weight + load weight) is predefined. In that way, a reduction in transport cost per weight of the load is accomplished i.e. the initial intention of cost reduction is accomplished. From environment preservation point of view, it is now possible to transport larger amount of load with same amount of energy used, i.e. it can be said that by using new (lighter) wagons in railroad freight transport, it is possible to transport the same amount of load with less energy consumed. This paper shows the savings accomplished by using modern wagons, on example of Falns wagon produced in Duro Dakovic Special Vehicles.

The main objective of this paper is the numerical analysis and calculation check of structural elements of one multipurpose kiosk. The model of multipurpose kiosk was modeled in 3D software and then model was used for determination of stress and deformation distribution using finite element method. Data input for numerical finite element method software are obtained from European standard Eurocode. Considered cases of loads on kiosk for calculation were snow load, wind actions and self-weight of the structure.

Paper deals with advanced closed-loop on-line control model for simulation of abrasive waterjet cutting and machining using accompayning physical phenomenon for surface quality control. Experimentally, a relationship was tested between surface roughness parameter Ra, traverse speed v mm/min and vibration parameter PtP, RMS and vRa generated during experimental cutting of AISI 309. Accuracy newly derived equations for surface roughness parameter prediction is described by Euclidean distances.

The aim of this work is to estimate the hoop residual stresses in the tubes manufactured by hot rolling technique, since in most cases they are delivered only normalized, but not stress relieved too. Therefore, there are surly residual stresses present in tubes which are result of manufacturing technique, but also of uneven cooling after production process. Within this work, hoop stress as the most relevant for pipes and tubes is estimated by two methods: incremental hole drilling method and splitting method. Splitting method is a method for direct assessment of hoop stress in pipe or tube, but the incremental hole drilling method gives the results of principal stresses, so in case of incremental hole drilling method, also the transformation of stresses is presented in order to obtain the hoop stress and make comparison to the splitting method. Although residual stresses are cause of collapse of many constructions, still in most cases of analysis and design of individual parts, structures and plants residual stresses are not taken into consideration. Residual stresses surly have significant effect on the fatigue behavior of materials as well as on the fracture toughness of material, therefore it is recommended to take them into account while calculating the lifetime of component or structure.

This paper describes the generation of energy sustainable and multi-functional conceptual variant of the technical system kiosk. From the requirement list, morphological matrix is made. The matrix contains partial functions and principal solutions of these functions. Applying AHP evaluation method, based on selected criteria, the best conceptual variant is selected.

The paper presents design process for concept variant for machine cutting raw rubber into ribbons. Using the flow function modelling method transformation of the operands was shown. Function as a part of the total transformation, causes a certain change of characteristics of the operand that is realised by the physical bearer of the function (technical solution). Technical solution is a machine for cutting raw rubber. The machine is constructed to allow reception of raw rubber rolls of various dimensions, as well as cutting into ribbons of various widths. The techno-economic evaluation was carried out and the best solution of the concept variant of the machine was chosen.

Preterm delivery occurs in about 11% of all pregnancies in the United States and is one of the leading causes of perinatal morbidity and mortality [1]. In the last two decades number of premature births has increased by 15% [2]. Premature rupture of fetal membranes alone is associated with 30 to 40 percent of all preterm births and is considered one of the main obstetrical complications resulting preterm delivery [3]. Factors that affect rupture of fetal membranes may be pathological, mechanical or biochemical. In order to understand the mechanical influences of fetal membrane rupture is necessary to examine the properties of the membrane. This paper presents characteristics of membranes that should be considered in examining mechanical properties of fetal membranes.

Paper describes the process of generating conceptual variants of the roof structure and foundation for energy - independent and multifunctional kiosk technical system. Morphological matrix for roof structure and foundation is based on a list of requirements. Generated variants were evaluated using a ranking technical evaluation method. Based on this method results, best variants are chosen and built into kiosk technical system.

Prema podacima dostavljenim od naručitelja, izvršen je proračun cijevnog priključka opterećenog unutarnjim tlakom (radni tlak 8 bar, ispitni tlak 16 bar) prema normi ASME B31.3 (2002) - Process Piping.

Finite element analysis of pipe joints and branches made of structural steel subjected to internal pressure has been performed. The influence of the pipe diameter, its thickness, and the angle change between pipes axes has been investigated numerically, and experimentally. Three experiments carried out by using strain gauges to measure strains at eight characteristic locations. Obtained experimental results verified numerical models. Based on the diagrams of pressure - the main deformation, using the method of double elastic slope and method of intersection of the tangents, limit pressures are determined based on the plastic collapse of pipe joints and branches.

The aim of this work is to describe a method that can be used as an alternative to thermal processing. The vibration method with the help of sub-resonant frequencies to the object aims to reduce residual stresses and secure dimensional stability of the object. Practical application of the method is shown through several examples where the treatment is applied. The advantages and drawbacks of sub- resonant frequencies are reviewed on the basis of recorded results showing reduced resonant frequencies as well as comparisons with residual stresses in the structure/construction before and after the vibration process.

The appearance of new materials and technology provides the modern and comprehensive approach to the process of constructing and designing new products. The process of constructing in the history was limited by choice of available materials and technologies which are able to make products. Modern approach to constructing can be applied in the development of a completely new product or in analysis and redesign of existing products. This paper analyzes design of electric guitar that dates back to the 50’s of the last century. It analyzes the basic function of the product. The primary function of the electric guitar is making a sound by vibrating of wires with predefined frequencies. Strings on the guitar require prestressing to produces sound of proper frequencies. The main lack of the existing design of the guitar, which is more than 60 years unchanged, is change of the preset frequency of strings with temperature change of the guitar parts. The change of temperature can stretch or shrink certain parts of the guitar including strings. Because of the different materials of the guitar neck and strings, shrinkage and stretching of the wires is not equal to the guitar neck. That causes a change in the tension of the wire, and hence the preset frequency. This paper analyzes change in frequency of strings depending on temperature change of parts of the guitar. Based on the analysis is proposed that the neck of the guitar should be manufactured from composite Verton UX03320 PPA. Temperature elongation of the proposed composite is equally to elongation of guitar strings. The newly proposed material can replace the maple tree that is commonly used for making the guitar neck.

Eave framework is analysed in this paper from standpoint of statics. Loads taken into account are self-weight, snow and wind influence. 3D model of eave framework is generated in the software PartSolution (Cadenas) with certain simplifications in geometry. Simplifications are taken into account in order to reduce costs of the numerical calculation, especially the FSI calculation. The resulting pressure distribution solution obtained from CFD calculation is set as the boundary conditions on the eave framework when performing the structural analysis. Solutions for equivalent stress as well as deformation are presented and analyzed. Also, solution for airflow prediction around the eave framework are presented in order to analyze if it is possible to perform some changes in the construction in means of reducing the air resistance and thus reducing the wind load on the construction.

This paper shows workflow for analyzing crankshaft strength and fatigue due to complex dynamic behavior. Crankshafts are subjected to multiaxial stress state with variable stress amplitudes during the lifetime. Such complex dynamic behavior needs to be analyzed with multibody dynamic simulation (MBS). Crankshaft stress analyses with dynamic loadings were done with finite element method. Inputs for fatigue evaluation are stress tensors for critical crankshaft areas. Multiaxial high cycle fatigue evaluation were done with using basic unit load cases (BLCs), which are superimposed with linear static stress analysis load history, and with directly usage of displacements and rotations history from dynamic analysis. All main journals and crank pins have the same simple fillet radius. The aim of this paper is to check crankshaft fillets structural durability for infinite life. Results from both analyses are compared. Load history for nodes are displacements and rotations in time-domain for one engine cycle, i. e. 720°.

The paper presents environment-based approach to the conceptual design and decision making of design parameters. The decision making model in the design process is an approach for establishing effective mapping and transformation process between product properties and domain requirements from environment. Decision making model of product properties such as requirements of environment (RE) is showed in the general evaluation process in the conceptual phase. Mathematical terminology and mathematical tools have been used for presentation of decision making model with respect to the impact on the environment as one model evaluation strategy parameters of eco-design products.

This paper presents a procedure for calculating the welded piping branch according to EN 12952-3, which defines the shaping and method of calculation of such components. In the experimental part of the paper stresses are measured the under internal pressure of 0-420 bar. Stresses were measured using strain gauges. The analysis of the calculated stresses and with the help of experimental methods for Y-shape pipe branch can conclude that the calculations according to standards are pretty strict compared to the real stresses that occur in real-world conditions.

U radu je prikazan postupak konstruiranja za održavanje korištenjem načela oblikovanja za proizvodnju i sklapanje (eng. Design for Manufacture and Assembly-DFMA). Izvršeno je pojednostavljenje klizača alatnog stroja koje se ne temelji na proračunu, nego prema pretpostavkama proizašlim iz DFMA načela. Ove pretpostavke su: pretpostavka o poštivanju dosadašnjeg načina spajanja dijelova, pretpostavka o smanjenju istovrsnih dijelova ako na njih djeluju mala naprezanja i pretpostavka o pojednostavljenju oblika dijelova. Ostvareno je povezivanje CAD sustava i DFMA analize na način da DFMA analiza usmjerava CAD sustave. Uzimanjem u obzir oblikovanja kod sklapanja i povezivanjem s CAD sustavima, olakšano je sklapanje dijelova, podsklopova i sklopova te na takav način smanjena cijena koštanja proizvoda i njegovo održavanje.

Preterm delivery occurs in about 11% of all pregnancies in the United States and is one of the leading causes of perinatal morbidity and mortality [1]. In the last two decades number of premature births has increased by 15% [2]. Premature rupture of fetal membranes alone is associated with 30 to 40 percent of all preterm births and is considered one of the main obstetrical complications resulting preterm delivery [3]. Factors that affect rupture of fetal membranes may be pathological, mechanical or biochemical. In order to understand the mechanical influences of fetal membrane rupture is necessary to examine the properties of the membrane.

The transmission of power in IC engines are from combustion in cylinders to piston and piston pin via the connecting rod to the crankshaft which is achieved by the fluid film lubrication in the bearings. The force applied to the connecting rod is dependent on the pressure distribution in the lubricant film and by the stiffness of the connecting rod. From that conclusion, the dynamic behavior of the connecting rod is crucial for structural design. Dynamic behavior include elastohydrodynamic lubrication in bearings. In this paper, large medium speed IC engine simplified connecting rod will be analysed by modern multy-body dynamic simulation in software AVL Excite 2010.1 [1]. Elastohydrodynamic behavior of big end bearing will be evaluated. Substructuring of finite element model was done in software Abaqus 6.10 [2].

The task of this paper is to structurally elaborate the mechanical gripper for handling cylindrical objects without human assistance or any other additional techniques. In the first part, the structural and functional features of the mechanical grippers are presented. A list of demands and wishes is also specified. The second part of the paper deals with the generation and evaluation of the principal solution. Using this mechanical gripper, cylindrical objects can be grasped and manipulated easily. Humanization of work was done and heavy physical work was avoided. It is applicable to closed facilities and for outdoor work. It is used for lifting concrete pipes, and for steel and plastic profiles.

Na primjeru dijelova pužnih presa za cijeđenje ulja i turbopuhala motora SUI analizirana su nova konstrukcijska rješenja. Snimanjem stanja utvrđeno je prebrzo trošenje i oštećivanje dijelova nosive konstrukcije pužne preše, a na turbopuhalu učestala pojava zaribavanja osovine propelera. Izvršena su metalografska i mehanička ispitivanja materijala kao i dimenzionalna kontrola. Analizirani su direktni i indirektni gubici. Zaključeno je da se pomoću polukarika može postići značajno smanjenje troškova sanacije oštećenih jarmova cjedila pužne prese, a da bi kod turbopuhala ugradnja odgovarajućeg senzora temperature u značajnoj mjeri smanjila opasnost zaribavanja osovine.

Car is designed using the software package Autodesk 3ds Max. Polygonal modeling method was used and designed car represent a new conceptual solution car design. After modeling a car in mentioned software, final digital images are generated too. Final digital images are generated using the Mental Ray rendering tool as a default rendering tool of Autodesk 3ds Max. Attention is given only to the external design of the car, while the interior is not modeled. Furthermore, using the software ANSYS Fluent, 2D simulation of the airflow around the side contour of the vehicle was made in purpose of making changes in the geometry of the vehicle to improve the design in terms of reducing air resistance and improving aerodynamics. Most attention of that is given in changing value of angle between the hood and front windshield of car, and analysing back of the car with and without the rear wing. Leading to the obtained 2D simulation and leading with modifications of initial 2D model, existing 3D car model is redesigned. Assumption is that new 3D car model is resulting with better aerodynamic properties. 3D analysis of redesigned car model in terms of mentioned changes is performed too in order to analyse possible improvements compared to the initial design.

U okviru ovoga rada dizajniran je automobil koristeći softver Autodesk 3ds Max. U tu svrhu korišten je poligonalni način modeliranja. Koristeći alat Mental Ray, metodom sjenčanja izrađene su realistične fotografije automobila, u svrhu što bolje prezentacije dizajna automobila. Nadalje, provedene su 3D simulacije strujanja zraka oko geometrije automobila koristeći softver Ansys CFX. Simulacije su provedene za dvije geometrije automobila, prva je inicijalni model automobila, a druga redizajnirani model u smislu povećanja kuta između poklopca motora i prednjeg vjetrobranskog stakla, te dodavanja stražnjeg krila. Simulacije su provedene u svrhu analiziranja mogućih poboljšanja u aerodinamičnom smislu smanjenja otpora zraka i poboljšanja aerodinamičnih svojstava u slučaju redizajnirane geometrije automobila.