Pero Raos

Pero Raos
University of Osijek | UNIOS · Faculty of Mechanical Engineering in Slavonski Brod

Full Professor, PhD

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63
Publications
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604
Citations

Publications

Publications (63)
Article
Full-text available
Polymer nanocomposites consist of a polymer matrix and reinforcing particles that have at least one dimension under 100 nm. The processing of nanocomposite polymers is the most important stage, determining the final properties of nanocomposites. Nanocomposites are now preferentially prepared by melt-mixing using conventional compounding processes s...
Article
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Additive Manufacturing (AM), the relatively young manufacturing technology of layer-based automated fabrication process for making three-dimensional physical objects directly from 3D CAD data set was originally called Rapid Prototyping (RP) when the first commercial process – Stereolitography was entered the market in 1987. This technology is still...
Article
Full-text available
The main objective of this research was to determine the deviations and eval-uate the dimensional accuracy of 3D printed camera casing models compared to the original models in the STL format. The study sample consisted of the 3D printed camera casing models and the same models in the STL format. The STL format came from Mcor in a set of sample mod...
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The paper reviews the process of surface layer development with the use of carbonitriding and carbonitriding with oxidation. Employed for that purpose was a modern and ecological method called ZeroFlow. Research was carried out using HS 6-5-2 steel. Single-component nitrifying atmosphere of ammonia NH3 was applied. The temperature of the processes...
Article
Natural gas is one of the most important energy sources of the modern age. Gas network delivers gas from the exploitation site to the end user. Flow meters are used to measure quantity of gas supplied and they must meet firm standards regarding measurement. G4 gas meters used in housholds are investigated in test laboratory. Experimental results ar...
Article
There is often a need to more precisely identify the extent of pathology and the fine elements of intracranial anatomic features during the diagnostic process and during many operations in the nose, sinus, orbit, and skull base region. In two case reports, we describe the methods used in the diagnostic workup and surgical therapy in the nose and pa...
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In the paper we are introducing guidelines and suggestions for use of 3D image processing SW in head pathology diagnostic and procedures for obtaining physical medical model by additive manufacturing/rapid prototyping techniques, bearing in mind the improvement of surgery performance, its maximum security and faster postoperative recovery of patien...
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The paper presents the results of investigation of the influence of conditions of forming emulsion and oil mist on the chip shape and surface roughness of X10CrNi18-8 stainless steel during turning. In the tests, the following machining operations have been compared: dry machining, cooling by the MQCL (Minimal Quantity Cooling Lubricat) method, coo...
Article
Polymeric materials processing is one of the fastest growing industries in the world. One of the most important method for processing polymeric materials is injection molding. The properties of an injection molded part depend upon the working material and upon the processing parameters as injection pressure, holding pressure, melting temperature, i...
Article
The paper shows the reader to the basic problems involved in the collection of data on production. It shows that there is the necessity of data collecting describes possible methods and advantages resulting from data analysis. It also refers to the systems of class ERP. It demonstrates, too, a simple way in which the system of data collection, expo...
Article
The nanocomposites are multiphase materials where at least one phase is in nanoscale, less than 100 nm, whereby a higher specific interfacial area is achieved. Due to their characteristic properties, the nanocomposites are nowadays being increasingly used for the engineering applications, and certainly will have a significant role in the materials...
Article
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Machine vision (system vision) comprises using computer vision in industry. While computer vision is focused mainly on image processing at the level of hardware, machine vision most often requires the use of additional hardware I/O (input/output) and computer networks to transmit information generated by the other process components, such as a robo...
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The analysis of the allowance distribution in pipe thread rolling with rollers of the identical thread crest rounding radius has been presented. Theoretical relationships and methodology for computing the embossing thread diameter with the assumed distribution of the embossing allowance as measured by the displaced material volume have been elabora...
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The objective of the investigation was to identify surface integrity of machined parts by turning and by Fused Deposition Modelling (FDM) additive method produced ones. Surface analysis was made by using novel metrology methods: auto correlation and gradient distribution. An Infinite Focus Measurement Machine (IFM) was used for the surface texture...
Article
High speed grinding methods are continuously being developed and have been highly accepted due to high productivity and resulting surface quality when machining materials dissimilar in physical and mechanical properties. Grinding wheels are the most important part of the entire technological system, in particular their stress state. Hence, the arti...
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The purpose of the study was to determine the coated carbide tool surface topography. The study included determining detailed identification of wear mechanisms occurring on the rake face and major flank in the process of turning the DSS. The results of wear occurring on the tool both points were compared for the period of the steady-state wear of t...
Article
The paper deals with testing the influence of welding time and environment temperature on electro fusion pipe weld properties. Central composite design experiment with two factors in the pre-selected limits was chosen for planning the experiment. Results obtained by measuring the internal pressure were statistically analyzed. Analysis gave the resp...
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Polymers that are created by the chemical polymerization of naturally occurring monomers are attracting considerable commercial interest in the last few years because of their non-toxicity, biodegradability and biocompatibility and use of feedstock that is renewable. The development of specialized lignin compounds, such as electrically conducting p...
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Heat distribution in machining is one of the phenomenological characteristics of this process because it significantly influences functional properties of machined surfaces. This paper deals with heat distribution during grinding of Ni alloy and its relationship to the quality of ground parts in terms of residual stresses. The analysis of the heat...
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The main objective of research was to determine the impact of internal lattice-shaped structure and building orientation (longitudinal and base alignment) on the tensile strength of 3D printed samples. Results of tensile test revealed that the honeycomb structured samples built by orienting along axis Y and aligned over their thinner bases exhibit...
Article
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There are many possibilities of rapid prototyping; however each technique has its own specificities and limitations. This paper presents an overview and brief analysis of different methods for rapid prototyping, with the aim to evaluate practical application of certain procedures in the casting industry and in the production of permanent casting co...
Article
Injection moulding process is one of the most important processes for the production of polymer parts. Effective tool for successful moulded part development is an approach of Rapid Product Development. This approach includes the application of Rapid Prototyping (RP) processes of obtaining physical models in an early stage of product development. R...
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Rapid prototyping procedures make it possible to produce relatively complicated geometries based on the computer 3D model of products in relatively short time. This requires that the respective product features have good quality, good mechanical properties, dimensional accuracy and precision. However, the number of available materials that can be u...
Article
This paper deals with new approach to life estimation of damaged thick-walled gas pipes made of high-density polyethylene (PE-HD). The most common approaches to polyethylene gas pipes durability prediction rely on methods of fracture mechanics, which involve defining a stress intensity factor experimentally. However, such tests are carried out on s...
Article
Polymers that are created by the chemical polymerization of naturally occurring monomers are becoming more attractive because of their non-toxicity, biodegradability, biocompatibility and renewability of the feedstock. Specialized lignin compounds are being developed, e.g. polyurethane foams made from renewable lignocelluloses materials. The lignoc...
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Based on the philosophic ideas of O. Spengler and Aristotle it has been determined that polymers are ancient since they reach back all the way to the origin of the basic natural organic and inorganic polymers. At the same time it has been noted that the word polymers is frequently used as a common name for plastics and elastomers. Since the basic n...
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Polazeći od fi lozofskih misli O. Spenglera i Aristotela, utvrđeno je da su polimeri prastari, jer sežu tamo do postanka osnovnih prirodnih organskih i anorganskih polimera. Istodobno je uočeno da se riječ polimeri učestalo upotrebljava kao zajedničko ime za plastiku i elastomere. Od osnovnih prirodnih organskih polimera: bjelančevina, nukleinskih...
Article
Estimation of dynamic behaviour of the turning process is of great interest in hard material machining. In hard turning, when depth of cutting and feed have low values, lead edge angle and passive force Fp are strongly dependant on real time value of cutting depth. Experimental tests and numerical modelling of tool/work piece contact line have been...
Article
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Natural and wood fibre plastic composites (WPC) are among the most rapidly growing markets within the plastics industry. They are manufactured by combining either wood or other natural fibers such as flax, hemp, jute or kenaf with polymers. Thermoplastic resins, such as polypropylene, polyethylene or polystyrene, are mixed with other materials (suc...
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Contemporary approaches regarding to infrastructure are more and more directed to new materials development for natural gas and other installations. The most recent development and application of the new materials pertain to sealant materials for sealing of threaded joints in gas pipeline installations and installations for other media. Based on pr...
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Full-text available
Rapid prototyping (RP) can substantially shorten the time and reduce the cost of developing a new product from the initial idea to production. Rapid prototyping can help in recognizing the basic defects whose subsequent correction may prove very expensive, especially if they have already been made when the product is ready for production. There are...
Article
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Both, experimental investigation and finite element analysis of single‐lap adhesive joints subjected to tension have been done to find out an optimal overlap length. As the adherend material aluminum was considered with the two component high‐strength engineering adhesive for the bonding of the layers. The thickness of the sheet metal layer was 1...
Article
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Different surface topographic techniques are being widely used for quantitative measurements of typical industrial aluminium oxide surfaces. In this research, specific surface of aluminium oxide layer on the offset printing plate has been investigated by using measuring methods which have previously not been used for characterisation of such surfac...
Article
Traditional use of steel pipes for water installations is now rarely practiced. Polypropylene pipes are used instead, considerably because of housing problems and increase of house building in Croatia in the last decade. Basic requirements demanded of water installations are prevention of leakage, particularly at the joining points of elements, the...
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Klasičan način postavljanja vodovodnih instalacija s čeličnim cijevima sve se rjeđe provodi, a umjesto čeličnih sve se više primjenjuju polipropilenske cijevi. Taj trend zamjene je u sve većem porastu na što značajan utjecaj ima i porast stanogradnje u posljednjem desetljeću u Republici Hrvatskoj. Pritom se kao temeljni zahtjev kojega instalacije t...
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COMPOSITE MATERIALS. One of the most difficult tasks is the bonding of materials with a low surface energy, such as polyolefines (PE and PP), silicones, polytetrafluoroethylene (PTFE) etc. This article analyses to what extend wood as filling material influences the bonding characteristics of polypropylene. A hardened two component epoxy adhesive an...
Article
Full-text available
This paper dealing with investigations of adhesive layer characteristics and it is a part of our continuous research on adhesively bonded joints. Previous experimental analysis has shown that bonding of different adherend materials using the same adhesive leads to the different behaviour of adhesive. This effect is more evident in numerical modelli...
Article
Veći broj faktora utječe na mehaničke karakteristike nosivosti lijepljenoga spoja. Čimbenici oblika i dimenzija spoja s najvećim utjecajem jesu ostvarena duljina preklopa i debljina sloja ljepila. U eksperimentalnom su dijelu rada analizirani ti faktori te definirane njihove optimalne vrijednosti pri kojima se uz najmanji utrošak materijala podloge...
Article
Single lap joint will be considered in the paper as one of the most frequently applied joint designs in engineering practice. The object of the paper is to find optimal values of geometrical parameters of joints (lap length and adhesive thickness) for the bonded joint to be dimensioned properly. At these optimal values it is possible to reach a max...
Article
The aim of investigations was the acquisition of sound pressure signal that appears near the cutting zone during the turning process. It was assumed and confirmed that the acquisition of noise signals has its advantages and limitations. The measurements were performed on a heat treatable steel Č1431, whereas CBN inserts were used during dry cutting...
Article
The load bearing capacity of adhesively bonded joints depends on many factors. The most decisive designing factors are lap length and thickness of the adhesive layer. In the experimental part of the present research these factors were analysed and their optimal values were defined. At these optimum values it is possible to reach the maximum load be...
Article
This paper deals with influence of lap length on bearing mechanical characteristics of single lap adhesively bonded joint. The problem of determination of an optimum lap length has been considered in partirular. The experimental specimens have been made of two materials - aluminium and stainless steel. All bonded joints have been realized using an...
Article
This paper deals with finite element calculation for large strain problems when using incompressible hyperelastic rubber material models. The Mooney-Rivlin and Van der Waals (Klilan) models will come into consideration. Both material models considered have been implemented in the FE code LAGAMINE for plain strain, axisymmetric and three-dimensional...
Article
Four models describing pure elastic behaviour of rubber are compared. These are the Neo-Hooke, Mooney-Rivlin, Van der Waals (Kilian) and Ogden models. This paper examines whether, and under what conditions, it is possible to predict experimental stress-strain curves using these models. Stress-strain curves are derived from uniaxial and pure shear (...
Article
The paper deals with the basics of temperature field behaviour in the mould for injection moulding of thermoplastics. Under the conditions of the heat-balanced (stable) process, this behaviour can be considered (quasi) steady-state. Based on the assumption of the steady-state process, a calculation of field dimensions has been made by means of anal...
Article
The-Hooke, Mooney-Rivlin and der Waals (Kilian) models describing pure elastic behaviour of rubber-like materials are compared. This paper examines when and under what conditions it is possible to predict experimental stress-strain curves using considered models. Stress-strain curves are derived from pure shear (biaxial) tests using specimens of SB...
Article
Considerations of flexibility according to available literature references are mainly related to metalworking machines. Analyses of flexibility in injection moulding have shown many differences in the use of the term flexibility. A new systematization of the levels of flexibility in the injection moulding of polymers based on the research conducted...
Article
The paper deals with the theoretical background and laws of specific volume changes of thermoplastic materials. The laws of specific volume changes differ for amorphous and crystalline thermoplastics because of their different characteristics. Graphically, the relationship between specific volume, pressure and temperature is shown by the p-v-T diag...
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This article deals with partial functions of a mould for the injection moulding of polymers. A morphological matrix is considered as a helpful means in the selection and optimisation of the conceptual design of mould partial functions. The application of a morphological matrix in methodical design is also considered. For the better understanding of...
Article
This paper presents a system analysis of molds for injection molding of polymers. Total and partial functions are defined. The morphological matrix is considered as helpful in the selection of optimum solutions for partial functions of molds. The applications of the morphological matrix in mold design is considered.
Article
The system analysis of the injection molding of polymers served as a basis for system analysis of injection mold as a subsystem of injection molding. The entire function of the mold and a series of its partial functions have been defined. The principles of the fundamental solutions of the individual partial functions making up the entire function o...
Article
Investigations have been made in shops, with two technical parts, using PF and a rubber compound. The results have shown that the Carslaw-Jaeger equation can be successfully used for calculating contact temperature T//C. The heat balance was established and only 27% of total heat for PF and 20% for rubber was used for processing. The remaining 73%...
Article
Full-text available
Adhesive bonding technology is one of the most recent assembling techniques applied in industry and maintenance. Adhesives are versatile and offer a number of advantages over fastening techniques, however, there are number of limitations associated with their use. One of the most difficult issues is bonding of low surface energy materials, such pol...
Article
On line sensing of cutting process has been used to detect tool failure indirectly, measuring acoustic emission, force, sound, vibration, etc. In these indirect methods, the signal magnitude, root mean square value, or magnitudes of the power spectrum, among others, are reported. These values indicate necessity for tool change typically via thresho...

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