IMPROVING PERFORMANCE AND APPLICABILITY OF GREEN COMPOSITE MATERIALS BY HYBRIDIZATION

A growing concern over environmental issues and the common interest to find a viable alternative to the use of glass or carbon composite reinforcements has led to an increased attention in ecologically sustainable polymer composites. These „green” materials are made by natural fibers, as reinforcement, filled with natural-organic fillers, i.e. derived from renewable or biodegradable sources. At the same time, this relatively new class of materials faces several limits in comparison to traditional composites especially regarding the properties of resistance. This paper investigates the advantages of use of combination of natural fibers for improving mechanical proprieties of „green” composite materials. At the moment, the prevailing opinion is that green composites are not usable in structural applications, and, as a consequence, have to be relegated to unworthy applications (as fillers). On the contrary, there are several evidences that mixing different natural fibers (in practice usually called „hybridization”) leads to an improvement of these material properties. Although usually quite limited in terms of percentage, these improvements from time to time allow a new enlargement in the fields of applications for green composites. Following a large state-of-the-art on green composites, including potential benefits and limits of these materials, the paper proposes several examples of hybridization showing its effect on mechanical proprieties.A growing concern over environmental issues and the common interest to find a viable alternative to the use of glass or carbon composite reinforcements has led to an increased attention in ecologically sustainable polymer composites. These „green” materials are made by natural fibers, as reinforcement, filled with natural-organic fillers, i.e. derived from renewable or biodegradable sources. At the same time, this relatively new class of materials faces several limits in comparison to traditional composites especially regarding the properties of resistance. This paper investigates the advantages of use of combination of natural fibers for improving mechanical proprieties of „green” composite materials. At the moment, the prevailing opinion is that green composites are not usable in structural applications, and, as a consequence, have to be relegated to unworthy applications (as fillers). On the contrary, there are several evidences that mixing different natural fibers (in practice usually called „hybridization”) leads to an improvement of these material properties. Although usually quite limited in terms of percentage, these improvements from time to time allow a new enlargement in the fields of applications for green composites. Following a large state-of-the-art on green composites, including potential benefits and limits of these materials, the paper proposes several examples of hybridization showing its effect on mechanical proprieties

Cost optimization of additive manufacturing in wood industry

© Faculty of Mechanical Engineering, Belgrade. Software packages for 3D design and additive manufacturing (AM) technologies, initially known as rapid prototyping (RP) have emerged during the last years, as a cutting edge solutions for custom prototyping. These new tools and technologies lower the design costs, but also allow rapid creation of fully functional components. This paper describes the FDM and 3DP rapid prototyping technologies that were used to create elements and tools in the wood industry field. Total costs of manufacturing related to the fabrication of sample elements and tools are analysed. One of the main recognised issues of wider application of rapid prototyping technologies is their still very high costs related to all production aspects, starting with a lack of available materials, material cost, up to high cost of available commercial equipment, usually focused only on specific solutions and limited range of materials. Generally, AM costs can be divided into the group of fixed costs and variable ones. This paper deals with the optimization of the production costs of fabricated elements in case of small-scale production, and optimization of variable costs (processing and post-processing, costs of enforcement, and material costs)

Implemenation of FEM and rapid prototyping in maxillofacial surgery

© Faculty of Mechanical Engineering, Belgrade. This paper investigates the opportunity of implementing FE simulations and rapid prototyping tecniques on titanium implant in maxillofacial surgery case based on osteotomy. Maxilla region was recorded by Cone Beam CT with high resolution and optimal radiation. Then, it followed the medical image reconstruction into 3D voxelized model. This model was converted both, to stl surface model for rapid prototyping, CAD modeling and FE mesh for simulation purposes with keeping good volume and dimensional consistency. Stl meshed surface was imported into CAD software, as initial 3d structure, which is used for parametric and customized design of implant. Since, the osteotomy is final application, it wassimulated the cutting and shifting of maxilla for proper correction by digital prototyping. Then, the fixation points for shifted maxilla were determined by surgeon to provide steady and tight joints between implanting screws and maxilla. Applied implant was given in initial standard flat configuration. Flat implant configuration was adapted by complex 3D bending in CAD software to be customized towards surface conformity of maxillofacial anatomy. By FE simulation in MSC Patran/Nastran, it was performed the stress analysis of implant with different thickness configurations and 3D bending, which provides the optimized implant model with best fit dimensions. Optimized implant model and corresponding body model were converted into physical models. RP model of maxilla was post-processed by cutting and boring to provide an adequate implant positioning according to digital prototypes. This approach facilitated the preparation of complex shaped implants in swept and lofted form, what had to be in high degree of conformity to anatomy surface. To approve a good practical opportunity, it was applied and tested in concrete surgery case of maxillofacial osteotomy

ADDITIVE MANUFACTURING OF FUNCTIONAL PARTS BASED ON MATERIAL EXTRUSION TECHNOLOGY

This paper presents the advantages and the process of making of complex functional parts using additive manufacturing technology. Design and manufacturing of components were performed at the Laboratory for Technology of Plasticity and Processing Systems at the Faculty of Mechanical Engineering in Banja Luka. The parts were designed using SolidWorks and Catia software packages. Then, CatalystEX and Simplify3D software packages were used to process the CAD model and to prepare it for 3D printing, which included defining of the process parameters, generating layers and support. Functional parts were produced on 3D printers based on the principle of material extrusion. The results of this study show that additive manufacturing technology, specifically technology based on material extrusion, enables very fast production of complex functional parts, with high accuracy and much lower costs and development time compared to conventional technologies