This study aims to investigate the surface roughness and the time consume printing on PLA material using FDM 3D printing on differences in layer height. A 3D printer machine, Creality Ender 3 was involved to manufacture the specimen. Furthermore, they tested with the SurftestSJ-301 Mitutoyo device to determine the roughness of surface object. The height of the test specimen layer varies from 0.05 mm to 0.25 mm with the increment of 0.5 mm for each variation, while the layer angle keep constant at zero degree (0°). Surface roughness and print time are analysed to determine the best design parameters. The test results show that, the greater of layer height has the rougher of the surface. In addition, the printing time is inversely proportional to surface roughness. The smallest of surface roughness occurs on the 0.05 mm of layer height, whereas the lowest occurs on the 0.25 mm of layer height. In addition, the optimize parameter occurs on 0.15 mm and 0.2 mm of layer height which surface roughness and printing time are 9.11 μm and 158 min respectively (Lh 0.15 mm), while the layer height of 0.20 mm for 120 min and 10.48 μm.

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The purpose of this study is to investigate the deformation pattern and of energy absorption (EA) in Polylactic Acid Carbon Crash Box. The crash box specimen was produced by using 3D printer machine. The quasi static testing method is performed to compress the specimen with a speed of 2 mm min−1 using universal testing machine. It was pressed until it reaches deformation of 80 mm from its original length of 120 mm. The deformation was analyzed in three different variations of wall thickness (Wt), 1.6 mm; 1.8 mm; and 2 mm. The deformation pattern and the maximum EA are analyzed to determine the best design specifications. The results show that the highest EA occurs on Wt 2 mm (357.986 J), whereas the lowest EA occurs on Wt 1.6 mm (224.012 J). The local buckling and discontinue folding consist on three model of crash box. In addition, the fragmentation is also formed on Wt 2 mm of crash box but it is not looked on remain models.

Purpose Mesh self-intersection defects and image noise may prevent 3D model reconstruction and mesh formation of bones with comminuted fractures, making it impossible to assemble 3D-printed fragments perfectly. This study proposes an algorithm to remove overlapping meshes and to smooth fracture surfaces in order to fabricate well-assembled 3D-printed bone. Methods 3D bone reconstruction, segmentation, and reduction were directly performed for three different classes of clinical fracture cases: pelvic 62-B1, 62-C2, and femur 31-A2.2. In contrast to the current Boolean operation, the proposed algorithm is not only capable of detecting overlapping meshes, but also recognizing the contact regions and detecting the boundary of each contact region. Hence, it was implemented in order to remove overlapping meshes and ensure that fragments fit together when physically assembled. Both gap distance and overlapping mesh errors during assembly of the 3D model from printed bone fragments were calculated and analyzed. Results and Conclusions Based on the comparison of results between the bone model before and after removing mesh defects, the RMS error is less than 0.33 mm and gap error is 3 mm, indicating that the proposed technique has high potential for eliminating mesh defects and providing a 3D-printed bone fracture model that is easy to assemble and disassemble.

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Fuse Deposition Modeling (FDM) 3D printing is one of additive manufacturing technology which physical 3D model is build up layer by layer. The support structure is almost involved on the process if overhang shape is met on the 3D model. It has main function to prevent the 3D printed model from collapsing. Commonly, the single material source of FDM 3D printer machine is to supply building two structure, structure of main 3D object and support structure. Hence, our goal optimizes the using of support material for reducing the main material usage. Furthermore, the sixteen of variation overhang angle is set to the 3D model. All models are printed into two kind of 3D printed model, printed model with support structure addition and without support addition. The weight of each 3D printed model is measured by weight scale with accuracy of tool is 10 -4 g. Then the quality and the weight of 3D printed model are compared and analyzed. The result shows that the average overweight of 3D printed model with support structure addition is 40.41% than without support structure addition. Furthermore, there are several the 3D printed models without support structure that fail printed on variety model with 0° until 11° of overhang angle. The conclusion of this study is that the support structure can prevent the 3D printed model from collapsing but it does not need be built up if the overhang angle more than 11°.

Along with the depletion of fossil fuel reserves in Indonesia, water resources can be used as an alternative source of energy. Pelton turbines are one type of water turbine that can be used. However, Pelton turbines still have weaknesses in terms of determining the optimal number of buckets and nozzles. This study aims to optimize the experimental variations in the number of buckets (Nb ), the diameter of the nozzle (Dj ), and the number of nozzles (Nj ) on the efficiency of the Pelton Turbine. The number of buckets was varied namely 24 and 27 pieces, nozzle diameter 5.5 mm and 7 mm, and number of nozzles using a single nozzle and double nozzle with horizontal direction. The research design began with Design of Experiment (DoE) using Taguchi method in Minitab 18.0. The next step was to calculate and then designed turbine using Autodesk Inventor 2016. The turbine design was then simulated using ANSYS Fluent 17.0 Workbench. The calculation of the largest efficiency using the number of 27 buckets double nozzle 5.5 mm producing an efficiency of 64, 69%. Based on Taguchi optimization delta result, the most influential variable on the efficiency was the nozzle diameter (M=0.1943).