List of articles (by subject) additive manufacturing
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Open Access Article
1 - Numerical simulation of multilayer cellular scaffolds with 3D and 1D elements
Hamid Reza khanaki Sadegh Rahmati Mohammad Nikkhoo Mohammad Haghpanahi Javad AkbariIn this paper, an attempt has been made to provide a numerical method for investigating the mechanical properties of multilayer scaffolding. These scaffolds can be used as implants in bone fractures. For this purpose two numerical simulation methods are introduced to pr MoreIn this paper, an attempt has been made to provide a numerical method for investigating the mechanical properties of multilayer scaffolding. These scaffolds can be used as implants in bone fractures. For this purpose two numerical simulation methods are introduced to predict the elastic properties of multilayer cell scaffolds. These simulations are based on two models: a 3D model with a volumetric element, and a 1D model with a linear element. To compare the results of these models, three types of two- and three-layer titanium alloy scaffolds have been simulated by the two methods. Also, Young's modulus of the scaffolds has been compared with the experimental conclusions of earlier studies. The results confirm that simulations with 1D models are more cost-effective compared to 3D ones. Additionally, because of the more reliable agreement of Young's modulus results of numerical modeling with the linear element (1.8 to 5 times) compared to the volumetric element (11 to 23 times) compared to the experimental findings, the numerical method with the linear elements can be a reliable tool for studying multilayer scaffoldings. Manuscript profile -
Open Access Article
2 - Investigation of Compressive Stresses of Stainless Steel 316L Diamond Lattice Structures Under the Effect of Spherical Connections Produced by SLM Additive Manufacturing
Behnam Ahmadi Roozbahani AliAkbar Lotfi NeyestanakIn this study, the compressive stresses of dodecahedron diamond lattice structures have been investigated. The finite element method has been used for Stress analysis. After the simulation, it was found that more stresses are applied at the junction of the struts of thi MoreIn this study, the compressive stresses of dodecahedron diamond lattice structures have been investigated. The finite element method has been used for Stress analysis. After the simulation, it was found that more stresses are applied at the junction of the struts of this structure due to the application of compressive force. For this purpose, the connection point of the structure’s struts was strengthened by spherical connections, and a new type of dodecahedron structure was created. The validation and effect of spherical connections in compressive stresses have been evaluated experimentally. Two types of diamond lattice structures are made of stainless steel 316L by the SLM method. The results show that in the same condition, the use of spherical connections with twice the diameter of the structure’s struts helps to strengthen the structure and increase its compressive strength by 18% compared to the simple structure. Manuscript profile -
Open Access Article
3 - Mechanical Properties of Materially and Geometrically Gradient Cellular Structures Manufactured with SLS 3D Printer Applicable as a Bone Implant
Ali Salehi Alireza Daneshmehr Kiyarash AminfarCellular structures are broadly used because of their exclusive properties in tissue engineering. This research proposes a new method, both in design and manufacturing, to engineer their mechanical properties considering gradient material and geometrical features and ev MoreCellular structures are broadly used because of their exclusive properties in tissue engineering. This research proposes a new method, both in design and manufacturing, to engineer their mechanical properties considering gradient material and geometrical features and evaluate the possibility of using created structures as bone implants. Schwarz-primitive surface has been utilized to design cellular structures with different porosities and unit cell sizes. A total of 18 cellular structures were designed and fabricated using the SLS 3D printer with a new unconventional approach in adjusting the settings of the machine, and their mechanical properties were extracted. The structures' internal properties were evaluated using the FESEM. Comparing the mechanical compressive test results showed that adjustments in material and geometry improved mechanical properties (such as the compressive moduli, compressive strength, and yield strength). For instance, in 3 mm samples, the elastic modulus in material gradient and geometrical gradient structures is 20% and 73 % higher than the minimum values of the uniform structure. FESEM imaging revealed that adjusting the absorbed energy by powders (controlled by laser characteristics) leads to the formation of natural voids with diameters in the range of 6 to 144 μm for the gradient structures. Evaluation of the designed structures showed that 6 of them (4 uniform porosity and 2 geometrically gradient) have mechanical behavior of the desired tissue. The research outcomes can assist in optimizing manufactured parts by SLS 3D printers with internal and external controlled properties to obtain more desirable mechanical characteristics, especially for tissue engineering applications. Manuscript profile -
Open Access Article
4 - Topological Optimization of Brake Pedal for Metal Additive Manufacturing: A Case Study
Batuhan Izgi Meltem Eryildiz Mirigül AltanAdditive Manufacturing (AM) has become popular for rapid prototyping and it is presently widely used in different branches of industry because of its advantages such as freedom of design, mass customization, waste minimization and the ability to manufacture complex shap MoreAdditive Manufacturing (AM) has become popular for rapid prototyping and it is presently widely used in different branches of industry because of its advantages such as freedom of design, mass customization, waste minimization and the ability to manufacture complex shape. AM is the process of making 3D object from computer model data by depositing of material layer by layer. Topology optimization is iterative modifying the shape and optimizing material within a given designs space for load, boundary condition thus leading to weight reduction of components. Thus, to form lightweight components which have great advantage where energy consumption is minimal, topology optimization is used. Reducing weight and decreasing the material usage while keeping the product functions are the main challenges. Studies on the integration of the topology optimization and additive manufacturing, specifically mass reduction attract considerable attention. The topology optimization process is employed in this case study, to redesign a lightweight automotive brake pedal to show the potential of topology optimized design for additive manufacturing. As a result of this study 54.07% weight reduction was achieved in the total mass. The thermo- mechanical analysis for additive manufacturing showed that the part without topological optimization 108 MPa of stress and 1,099 mm of displacement were obtained and after optimization they were 196,1 MPa and 1,295 mm, respectively. Manuscript profile -
Open Access Article
5 - Different Geometry Design Structures of Tissue Scaffolds for Additive Manufacturing
amirhossein Ehsani sadegh rahmati Mohammad Nikkhoo Shahram Etemadi Haghighi Mohammad HaghpanahiThe design and manufacturing cubic porous scaffolds are a considerable notion in tissue engineering (TE). From Additive manufacturing (AM) perspective, it has attained high appeal in the string of TE during the past decade. In the view of TE, the feasibility of manufact MoreThe design and manufacturing cubic porous scaffolds are a considerable notion in tissue engineering (TE). From Additive manufacturing (AM) perspective, it has attained high appeal in the string of TE during the past decade. In the view of TE, the feasibility of manufacturing intricate porous scaffolds with high accuracy contrast to prominent producing methods has caused AM the outstanding option for manufacturing scaffold. From design perspective, porous scaffold structures play a crucial task in TE as scaffold design with an adequate geometries provide a route to required strength and porosity. The target of this paper is achieve of best geometry to become an optimum mechanical strength and porosity of TE scaffolds. Hence, the cubic geometry has been chosen for scaffold and Cube, Cylinder and Hexagonal prism geometries have been selected for pore of structures. In addition, for noticing the porosity effects, pore size has been chosen in three size, and a whole of nine scaffolds have been designed. Designed scaffolds were generated using Fused Deposition Modeling (FDM) 3D Printer and dimensional specifications of scaffolds were evaluated by comparing the designed scaffolds with Scanning Electron Microscope (SEM). The samples were subjected to mechanical compression test and the results were verified with the Finite Element Analysis (FEA). The results showed that firstly, as the porosity increases, the compressive strength and modulus of elasticity obviously decreased in all geometry pore scaffolds. Secondly, as the geometry changes in similar porosity, cubic pore scaffold achieved higher compressive strength and modulus of elasticity than cylinder and hexagonal prime. Experimental and FEM validated results proposed a privileged feasible pore geometry of cubic scaffold to be used in design and manufacturing of TE scaffolds. Manuscript profile -
Open Access Article
6 - Feed Stock Fabrication of AISI 4605 Steel for Fused Deposition Modeling and Sintering and Designing of Its Extruder Mechanism
Amir Rahimi Jamal ZamaniFused Deposition Modeling and Sintering (FDMS) is one of the indirect and emerging processes of Additive Manufacturing (AM) for the production of metal parts, which is a combination of AM process and Metal Injection Molding (MIM). This study laboratory made a raw materi MoreFused Deposition Modeling and Sintering (FDMS) is one of the indirect and emerging processes of Additive Manufacturing (AM) for the production of metal parts, which is a combination of AM process and Metal Injection Molding (MIM). This study laboratory made a raw material (Feed Stock) composing of high percentage of metal powder (particle in nano-scale) and polymeric materials; and then, designed an extruder to simulate melting and extruding process by Computational Fluid Dynamic (CFD). The different variables such as the nozzle diameter (D) of 1, 2, 3 and 4 mm and compression zone length (L2) of 100, 200 and 300 mm were simulated to investigate their impacts on flow rate and required torque to rotate screw. The findings showed that components of feed stock for high physical and mechanical properties of FDMS should account for 55 wt.% of paraffin wax, 25 wt.% of polypropylene, 15 wt.% of carnauba wax and 5 wt.% of stearic acid with optimum percentage of metal powder of 90 wt.%. Also, the optimum value of extruder diameter and compression zone length were 2mm and 200 mm, respectively. Manuscript profile -
Open Access Article
7 - Investigating the Effect of Separation Speed and Image Cross-Section Geometry on The Separation Force in DLP Method using FEP and PP Polymer Membranes
Siavash Moayedi Manizani Jamal Zamani Mohammad Salehi Mohammad Taghi shayestehOne of the most challenging issues in DLP 3D printing is separation. Thus, the capability to employ a variety of polymer membranes can considerably aid in the development of the DLP technology. The primary purpose of this study is to thoroughly explore the characteristi MoreOne of the most challenging issues in DLP 3D printing is separation. Thus, the capability to employ a variety of polymer membranes can considerably aid in the development of the DLP technology. The primary purpose of this study is to thoroughly explore the characteristics influencing separation force and time on the FEP industrial membrane and the proposed PP membrane. Therefore, the impact of image cross section geometry and separation speed on separation force and separation time is investigated. As a consequence, changing the percentage of surface porosity has a negligible effect on the amount of separation force. According to the findings, reducing the cross-sectional area by 1.36% reduced the separation force by 6.5 times. Moreover, the outcomes are consistent with the mathematical model given. the separation force rose by 230% in the FEP membrane with an increase of 96 times of the speed, whereas the separation time decreased by 18.8 times. For the proposed PP membrane, as the speed increases, the separation force rate increases by 175% and the separation time falls by 29.6 times. The aforementioned findings show that the PP film may be used as a practical and affordable solution with quick separation that can reduce printing time when producing three-dimensional lattice pieces at varying speeds. Manuscript profile