Review on Additive Manufacturing of Multi-Material Parts:Progress and Challenges

Additive manufacturing has already been established as a highly versatile manufacturing technique with demonstrated potential to completely transform conventional manufacturing in the future. The objective of this paper is to review the latest progress and challenges associated with the fabrication of multi-material parts using additive manufacturing technologies. Various manufacturing processes and materials used to produce functional components were investigated and summarized. The latest applications of multi-material additive manufacturing (MMAM) in the automotive, aerospace, biomedical and dentistry fields were demonstrated. An investigation on the current challenges was also carried out to predict the future direction of MMAM processes. It was concluded that further research and development is needed in the design of multi-material interfaces, manufacturing processes and the material compatibility of MMAM parts

Mechanical and Thermal Analyses of Metal-PLA Components Fabricated by Metal Material Extrusion

Metal additive manufacturing (AM) has gained much attention in recent years due to its advantages including geometric freedom and design complexity, appropriate for a wide range of potential industrial applications. However, conventional metal AM methods have high-cost barriers due to the initial cost of the capital equipment, support, and maintenance, etc. This study presents a low-cost metal material extrusion technology as a prospective alternative to the production of metallic parts in additive manufacturing. The filaments used consist of copper, bronze, stainless steel, high carbon iron, and aluminum powders in a polylactic acid matrix. Using the proposed fabrication technology, test specimens were built by extruding metal/polymer composite filaments, which were then sintered in an open-air furnace to produce solid metallic parts. In this research, the mechanical and thermal properties of the built parts are examined using tensile tests, thermogravimetric, thermomechanical and microstructural analysis

*WINNER* Experimental and numerical characterization of functionally graded materials fabricated by the fused filament fabrication process

In this research study, mechanical and numerical characterization of functionally graded materials (FGM) fabricated by the multi-material fused filament fabrication (FFF) process have been studied. Design and digital fabrication of tensile, flexural, and compression samples have been performed using the voxelization method. Test samples were mechanically tested, and the results showed that the strength and modulus of ABS material enhanced significantly with the addition of PC material into the ABS matrix. Since the interface of multi-material parts is crucial and needs substantial improvement, different interface patterns were designed and mechanically tested using the tensile test method. Tensile strength of gradient pattern yielded better results than other joint types such as interlock and direct interface. Analysis of variance was also applied to understand the process-property-structure relationships. Microstructural samples showed that there are periodic voids between adjacent beads and layers of FFF-made parts. Therefore, a numerical homogenization method has been applied to obtain a mesoscale material property using Ansys Material Designer before performing macroscale finite element implementation. The results of numerical methods showed less than 10% error with respect to the experimental test results. Overall, the FFF process with FGM could have potential applications in medical, structural, and automotive industries by locally varying material properties. This study presents a unique method of fabricating FGM structures with a low-cost manufacturing process

Hazar Denizi’nde meydana gelen olumsuz dışsallıklar ve çözüm önerileri

ÖZETHAZAR DENİZİ’NDE MEYDANA GELEN OLUMSUZ DIŞSALLIKLAR VE ÇÖZÜM ÖNERİLERİHazar Denizi dünyanın en büyük gölüdür. Azerbaycan, İran, Rusya, Kazakistan ve Türkmenistan ile çevrelenen Hazar Denizi çok büyük sayıda ekosisteme de ev sahipliği yapmaktadır. Hazar Denizi son yıllarda birikmiş çevre sorunlarının baskısını hissetmektedir. 1938 yılında petrol üretimine başlanan Hazar Denizi’nde tabiatı ve çevreyi koruma hususları göz ardı edilmiş, deniz ve denize dökülen nehirler bu süreçte ağır metallerle ve diğer atıklarla kirlenmiş, su seviyesinde oldukça sık bir şekilde ortaya çıkan yükselmeler ise, bu denizde olumsuz dışsallıkların birikimli olarak artmasına neden olmuştur. Hazar Denizi’nin maruz kaldığı sorunların gelecekte daha da ağır sonuçlara neden olmaması için biran önce çözüm yönünde adımların atılmasına ihtiyaç olduğu açıktır. Bu çalışmada, Hazar Denizi’nde meydana gelen olumsuz dışsallıkların nedenleri ile bu dışsallıkların giderilmesinde karşılaşılan zorlukların nasıl aşılabileceği hususları ele alınarak bu konuda neler yapılabileceği sorusuna cevap aranmıştır. Tespit edilen sorunlara kalıcı çözümler getirilebilmesinin ise yalnızca bölge ülkelerinin büyük çabası ve gerekli finansal kaynakları bulabilmelerine değil, aynı zamanda uluslararası kurumlarla etkin işbirliği sağlayabilmelerine de bağlı olduğu sonucuna ulaşılmıştır. ABSTRACTNEGATIVE EXTERNALITIES ORIGINATING FROM THE CASPIAN SEA AND SOLUTION PROPOSALCaspian Sea is the biggest lake in the world. Surrounded by Azerbaijan, Iran, Russia, Kazakhstan and Turkmenistan, Caspian Sea hosts lots of ecosystems. In the recent years, it has felt the pressure of the accumulated environmental problems. In the Caspian Sea where petroleum production started in 1938, the question of protecting the nature and environment was disregarded, the sea and the rivers pouring into the sea were contaminated in the process by heavy materials and other waste, and the frequent rise in the water level caused the cumulative increase of negative externalities in this sea. It is obvious that there is a need to take steps for solution so that the problems facing Caspian Sea will not result in heavier consequences in the future. In this study, an answer to the question of what could be done is sought by discussing the reasons behind negative externalities occurring in the Caspian Sea together with the case of how to overcome the difficulties encountered in removing these externalities. It is concluded that attaining a permanent solution depends not only on the great effort of the countries in the region and their obtaining necessary financial resources but also on their securing an efficient cooperation with international institutions

Impact of economic growth on income distribution in East Asian emerging economies

Income inequality is one of the main topics that worried economists in recent decades. It became more popular, especially starting with the integration process of East Asian economies’ to the global market as a result of the globalization process. And there are lots of approaches on economic growth’s positive and negative effects on income distribution. Its impact on income distribution has been tested in the essay with two models between 2000 and 2018. In the first model, 6 variables for 7 East Asian emerging economies have been selected, and in the second model, 4 variables for only China has been selected and tested. As a result of the regressions, some indicators of economic growth have a positive impact on income distribution and several of them has affected positively. And one of the main variables results also controversial. Although, inward FDI played an important role in an increase in income inequality in 7 Asian miracle economies, its effect on income distribution was positive in China and resulted in a decrease in the Gini coefficient which means a decrease in income inequality

Hazar Denizi’nde meydana gelen olumsuz dışsallıklar ve çözüm önerileri

HAZAR DENİZİ’NDE MEYDANA GELEN OLUMSUZ DIŞSALLIKLAR VE ÇÖZÜM ÖNERİLERİ Hazar Denizi dünyanın en büyük gölüdür. Azerbaycan, İran, Rusya, Kazakistan ve Türkmenistan ile çevrelenen Hazar Denizi çok büyük sayıda ekosisteme de ev sahipliği yapmaktadır. Hazar Denizi son yıllarda birikmiş çevre sorunlarının baskısını hissetmektedir. 1938 yılında petrol üretimine başlanan Hazar Denizi’nde tabiatı ve çevreyi koruma hususları göz ardı edilmiş, deniz ve denize dökülen nehirler bu süreçte ağır metallerle ve diğer atıklarla kirlenmiş, su seviyesinde oldukça sık bir şekilde ortaya çıkan yükselmeler ise, bu denizde olumsuz dışsallıkların birikimli olarak artmasına neden olmuştur. Hazar Denizi’nin maruz kaldığı sorunların gelecekte daha da ağır sonuçlara neden olmaması için biran önce çözüm yönünde adımların atılmasına ihtiyaç olduğu açıktır. Bu çalışmada, Hazar Denizi’nde meydana gelen olumsuz dışsallıkların nedenleri ile bu dışsallıkların giderilmesinde karşılaşılan zorlukların nasıl aşılabileceği hususları ele alınarak bu konuda neler yapılabileceği sorusuna cevap aranmıştır. Tespit edilen sorunlara kalıcı çözümler getirilebilmesinin ise yalnızca bölge ülkelerinin büyük çabası ve gerekli finansal kaynakları bulabilmelerine değil, aynı zamanda uluslararası kurumlarla etkin işbirliği sağlayabilmelerine de bağlı olduğu sonucuna ulaşılmıştır. ABSTRACT NEGATIVE EXTERNALITIES ORIGINATING FROM THE CASPIAN SEA AND SOLUTION PROPOSAL Caspian Sea is the biggest lake in the world. Surrounded by Azerbaijan, Iran, Russia, Kazakhstan and Turkmenistan, Caspian Sea hosts lots of ecosystems. In the recent years, it has felt the pressure of the accumulated environmental problems. In the Caspian Sea where petroleum production started in 1938, the question of protecting the nature and environment was disregarded, the sea and the rivers pouring into the sea were contaminated in the process by heavy materials and other waste, and the frequent rise in the water level caused the cumulative increase of negative externalities in this sea. It is obvious that there is a need to take steps for solution so that the problems facing Caspian Sea will not result in heavier consequences in the future. In this study, an answer to the question of what could be done is sought by discussing the reasons behind negative externalities occurring in the Caspian Sea together with the case of how to overcome the difficulties encountered in removing these externalities. It is concluded that attaining a permanent solution depends not only on the great effort of the countries in the region and their obtaining necessary financial resources but also on their securing an efficient cooperation with international institutions

Additive Manufacturing of Magnetic Materials

This 17-page module, from Tennessee Technological University, "introduces students to the additive (AM) methods used in fabricating magnetic materials." This module briefly covers "magnetic properties, types of magnetic materials, AM technologies used to produced these magnets, and application areas." After completing the module, students will gain understanding of the working principles of AM manufacturing methods and be able to:define the types of materials used in AM,provide fundamental knowledge on magnetic properties,describe AM processing techniques, andunderstand how AM-made magnets are used in real applications and the advantages and disadvantages of AM methods

Tensile and Fatigue Analysis of Functionally Graded Materials produced by Fused Filament Fabrication

The aim of this research study is the design, fabrication, and mechanical characterization of functionally graded composite materials using the fused filament fabrication (FFF) process. Chopped carbon fibre reinforced Polyethylene Terephthalate Glycol (CCF-PETG) and CCF-Nylon materials are fabricated by the Zmorph Fab desktop machine. The digital design of gradient structures is achieved by the voxelization process of the computer aided design (CAD) files. One of the main drawbacks of FFF parts is weak in shear strength that is due to the orientation of the raster plane, so FGM is one of the ways to enhance the mechanical properties of the material. Tensile behaviour of FGM parts fabricated in various processing parameters such as print directions, infill orientations, layer heights, etc. Tensile fatigue tests with a stress ratio of 0.1 were performed on each specimen at 90, 80, 70, and 60% of UTS. This knowledge-based study will be conducted with the hypothesis that the tensile strength of CF PETG and CF Nylon materials are less than that of functionally graded CF PETG and CF Nylon materials. The specimen's longest fatigue life was found at a stress level of 60%. This study presents a first-of-its-kind experimental examination of FGM tensile and fatigue characteristics

Processing and Characterization of 3D-Printed Polymer Matrix Composites Reinforced with Discontinuous Fibers

The objective of this study is to fabricate discontinuous fiber (short fiber) reinforced polymer matrix composite material (CM) by additive manufacturing (AM) technology using single extruder 3D printer. For this study, short carbon fibers (diameter = 7.2μm, length = 150μm) reinforced filaments were extruded with fiber concentrations of 3% - 7.5% in volume. Input process parameters used for 3D printing to obtain good quality short carbon fiber (SCF) reinforced polymer specimens are reinforcement percentage and printing speed by fixing nozzle temperature, layer thickness, bed temperature and print orientation. It was analyzed that the surface characteristics and mechanical performance of 3D printed samples are greatly influenced by varying input process parameters. Scanning electron microscopy was performed to observe microstructural behavior of 3D printed samples. Tensile strength, ductility, and toughness were examined to validate the adhesiveness of the matrix and reinforcement. From the microhardness test, it was observed that the hardness properties are significantly affected by increasing the reinforcement percentage. The results obtained in this study could be quite useful in fabricating polymer matrix composites (PMCs) with improved overall characteristics for applications in automotive industry and medical field.Mechanical Engineerin

Experimental Analysis of Functionally Graded Materials produced by Fused Filament Fabrication

Multi-material additive manufacturing has grabbed tremendous attention in the research community. In this investigation, a multi-material single extrusion system was used to fabricate the combination of chopped carbon fiber reinforced Polyethylene Terephthalate Glycol (CF- PETG) and Thermoplastic Polyurethane (TPU) materials with gradient transition for a more robust material interface. Various patterns such as the 20, 40, 60, and 80% by volume blend of CF-PETG and TPU materials are designed, printed, and analyzed to understand their tensile and fatigue behaviors. Tensile–tensile fatigue tests with a stress ratio of 0.1 were performed on each specimen at 80% of UTS. The characterization of functionally gradient material interface and direct transition patterns were conducted for comparison. The results showed that gradient change in material concentrations from soft to hard material has significantly enhanced the interface strength.Mechanical Engineerin