Investigation of Mechanical Properties of Al7Si/ SiC and Al7SiMg/SiC Composites Produced by Semi Solid Stir Casting Technique_Turnitin

Sulardjaka, Sri Nugroho, Suyanto and Deni Fajar Fitrian

Characterization of PLA/PCL/Nano-Hydroxyapatite (nHA) biocomposites prepared via cold isostatic pressing

Hydroxyapatite has the closest chemical composition to human bone. Despite this, the use of nano-hydroxyapatite (nHA) to produce biocomposite scaffolds from a mixture of polylactic acid (PLA) and polycaprolactone (PCL) using cold isostatic pressing has not been studied intensively. In this study, biocomposites were created employing nHA as an osteoconductive filler and a polymeric blend of PLA and PCL as a polymer matrix for prospective usage in the medical field. Cold isostatic pressing and subsequent sintering were used to create composites with different nHA concentrations that ranged from 0 to 30 weight percent. Using physical and mechanical characterization techniques such as Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and density, porosity, tensile, and flexural standard tests, it was determined how the nHA concentrations affected the biocomposite’s general properties. In this study, the presence of PLA, PCL, and nHA was well identified using FTIR, XRD, and SEM methods. The biocomposites with high nHA content showed intense bands for symmetric stretching and the asymmetric bending vibration of PO43−. The incorporation of nHA into the polymeric blend matrix resulted in a rather irregular structure and the crystallization became more difficult. The addition of nHA improved the density and tensile and flexural strength of the PLA/PCL matrix (0% nHA). However, with increasing nHA content, the PLA/PCL/nHA biocomposites became more porous. In addition, the density, flexural strength, and tensile strength of the PLA/PCL/nHA biocomposites decreased with increasing nHA concentration. The PLA/PCL/nHA biocomposites with 10% nHA had the highest mechanical properties with a density of 1.39 g/cm3, a porosity of 1.93%, a flexural strength of 55.35 MPa, and a tensile strength of 30.68 MPa

Influence of layering sequences on tensile properties of hybrid woven Jute/Ramie fibre reinforced polyester composites

Many researchers around the globe have shifted their focus onto the renewable resources lately. This trend is due to the number of resources that are almost reaching its critical stage hence the exploration of natural fibre composites has also caught the world's attention. In this research the effect of the number of layers, stacking sequences, and orientation of plain weave jute and ramie fibre single/hybrid composites on tensile properties were investigated. The stacking sequences consisted of two and three layered of laminated composite of pure jute (JJ, JJJ), pure ramie (RR, RRR) and ramie/ramie/ramie (RRR), whereas jute/ramie (JR), jute/jute/ramie (JJR), jute/ramie/jute (JRJ), ramie/jute/ramie (RJR), jute/ramie/ramie (JRR) were included under the hybrid composites category. The comparisons of tensile properties for each of the pure polyester, single, and hybrid composites were evaluated afterwards. The tensile strength and tensile modulus of the composites that was constructed with different fibre direction of warp and weft for each layer were also analyzed. The hand lay-up method was employed for all the fabrication of the composite specimens. From the results, it was observed that the tensile properties of the skin-core type composites (RJR, JRJ) have showed a better performance compared to the skin-eccentric types (RRJ, JJR) with similar ramie content. Attributed to a good fibre rigidity of Ramie fibre, the tensile strength and tensile modulus values could be enhanced with the addition of the ramie content in the composite mixture. The tensile properties were proven to also be improved with the increase number of woven layers in the composite. The Jute/ramie hybrid composite has exhibited very high potential in the future development of the automotive industry

Application of micromechanical modelling for the evaluation of elastic moduli of hybrid woven jute–ramie reinforced unsaturated polyester composites

Woven laminated composite has gained researchers’ and industry’s interest over time due to its impressive mechanical performance compared to unidirectional composites. Nevertheless, the mechanical properties of the woven laminated composite are hard to predict. There are many micromechanical models based on unidirectional composite but limited to the woven laminated composite. The current research work was conducted to evaluate elastic moduli of hybrid jute–ramie woven reinforced unsaturated polyester composites using micromechanical effectiveness unidirectional models, such as ROM, IROM, Halpin–Tsai, and Hirsch, which are based on stiffness. The hybrid jute–ramie laminated composite was fabricated with different layering sizes, and the stacking sequence was completed via hand lay-up with the compression machine. Tensile modulus values for hybrid composites are between those for single jute and single ramie. Obtained p-values less than 0.05 prove the relationship between layering size and tensile modulus. This study showed that several micromechanical models, such as Halpin–Tsai’s predicted value of homogenized mechanical properties, were in good agreement with the experimental result. In the case of the hybrid composite, the micromechanical model deviates from the experimental result. Several modifications are required to improve the current existing model. A correlation function was calculated based on the differences between the elastic modulus values determined experimentally and those derived from each micromechanical model calculation

PELATIHAN SOFTWARE RHINOCEROS DAN MAXSURF UNTUK MENINGKATKAN KOMPETENSI DESAIN 3D PENGRAJIN KAPAL TRADISIONAL DI PESISIR PEKALONGAN

ABSTRAKKota Pekalongan terletak di pantai utara Jawa Tengah dimana wilayah pesisir utara ini terdapat potensi yang dapat dikembangkan menjadi aset yang berharga bagi bangsa yaitu para pembuat kapal tradisional. Dalam pelaksanaannya, baik tipe ataupun bentuk kapal yang dibangun, berdasarkan pengalaman kapal-kapal yang pernah dibuat sebelumnya, tanpa melalui perhitungan dan penggambaran terlebih dahulu, sehingga dalam beberapa kasus terhadap pesanan kapal yang berbeda bentuknya, maka pengrajin ini akan mengalami kesulitan. Minimnya pengetahuan tentang gambar teknik juga menyebabkan para pengrajin kapal tradisional tidak dapat menggambar lambung kapal mereka. Hal ini menyebabkan perlunya sosialisasi mengenai teknologi perkapalan kepada pengrajin kapal di Kota Pekalongan terutama dibidang rancang bangun (design) dan konstruksi kapal agar terdapat standar baku mengenai konstruksi kapal kayu yang sesuai dengan standar yang ada seperti Biro Klasifikasi Indonesia (BKI). Pelatihan dilakukan dengan metode presentasi, demonstrasi, serta praktik langsung. Untuk mengukur pencapaian maka dilakukan pretest dan posttest yang dilakukan sebelum dan sesudah pelatihan. Hasil kuesioner menunjukkan adanya peningkatan pengetahuan peserta pelatihan desain kapal. Sebelum dilakukan pelatihan, rata-rata pengetahuan peserta sebesar 26% dalam memahami desain kapal dan 33% dalam memahami analisa tahanan kapal, kemudian mengalami peningkatan menjadi rata-rata sebesar 76% untuk pemahaman desain kapal dan 77% untuk analisa tahanan kapal setelah diberi pelatihan. Kata kunci: desain; pengrajin; kapal kayu; karakteristik kapal ABSTRACTThe city of Pekalongan is located on the north coast of Central Java where there is potential for this northern coastal region to be developed into a valuable asset for the nation, namely traditional shipbuilders. In practice, both the type and shape of the ship built, based on the experience of ships that have been made before, without going through calculations and drawings beforehand, so that in some cases orders for ships with different shapes, these craftsmen will experience difficulties. The lack of knowledge about technical drawings also causes traditional shipbuilders to be unable to draw their hulls. This causes the need for socialization regarding shipping technology to ship craftsmen in Pekalongan City, especially in the field of ship design and construction so that there are standard standards regarding wooden ship construction in accordance with existing standards such as the Indonesian Classification Bureau (BKI). The training is carried out using presentation methods, demonstrations, and hands-on practice. To measure achievement, a questionnaire was filled out before and after the training. The results of the questionnaire showed an increase in the knowledge of ship design training participants. Before the training, the average knowledge of the participants was 26% in understanding ship design and 33% in understanding ship resistance analysis, then increased to an average of 76% for understanding ship design and 77% for ship resistance analysis after being given training. Keywords: design; craftsmen; wooden ships; ship characteristic

Enhancement of flexural modulus and strength of epoxy nanocomposites with the inclusion of functionalized GNPs using Tween 80

In this work, epoxy nanocomposite was prepared with the inclusion of unfunctionalized as-received GNPs (ARGNPs) and functionalized GNPs using surfactant Tween 80 (T80GNPs) in the epoxy resin using a mechanical stirrer. ARGNPs were used as it is, while T80GNPs were prepared through the adsorption of surfactant onto GNPs’ surface using a sonication procedure in an ultrasonic bath. Characterization of nanoparticles using SEM shows that ARGNPs indicated a softer image representing a thinner layer of graphene stacks compared to T80GNP which has a tangible solid-looking image resulting from the sedimentation during the process of filtration. Elementally, both ARGNPs and T80GNPs were found to contain carbon, oxygen, and sulfur, as indicated by the EDX spectrum, with the C/O ratio for T80GNPs being 34.7% higher than that for ARGNPs, suggesting the adsorption of Tween 80 molecules on the GNPs after functionalization. FTIR spectroscopy confirms the attachment of Tween 80 molecules on GNPs surface with T80GNPs spectrum indicated higher peak intensity than ARGNPs. Flexural testing demonstrated that the addition of 0.9 wt.% ARGNPs and 0.9 wt.% T80GNPs to the epoxy increased the modulus of the nanocomposites to 72.1% and 82.6%, respectively, relative to neat epoxy. With the same amount of particle content, both nanocomposites showed increased strength, with ARGNPs and T80GNPs exhibiting strengths of 70.5% and 87.8%, respectively, relative to neat epoxy

Influence of Post-Heat Treatment on the Characteristics of FeCrBMnSi Coating on Stainless Steel 304 Substrate Prepared by Twin Wire Arc Spray (TWAS) Method at Various Stand-off Distance

Twin wire arc spray (TWAS) is a type of thermal spray coating technology that has been extensively researched to improve the service life and overcome wear, cavitation and corrosion in pump impellers. This study aims to investigate the effect of post-heat treatment on the properties of FeCrBMnSi coatings fabricated by the Twin Wire Arc Spray (TWAS) method on 304 stainless steel substrates with varying stand-off distances. NiAl and FeCrBMnSi were employed as bond coats and top coats in this study. The substrate material was sandblasted before the coating process to achieve a surface roughness of 75–100 µm. The TAFA 9000 Electrical Wire-Arc Spraying machine's voltage (V), current (A), and compressed air pressure (Bar) were set to 28.4; 150; and 5, respectively. The coating operation was performed at 100, 200, and 300 mm stand-off distances. The specimens were then post-heated for 3 hours at 500°C and 700°C in a Thermolyne F6010 Furnace Chamber. The quality of the coating produced in this study was evaluated using thickness, hardness, wear, bond strength, micrography, and SEM (Scanning Electron Microscope) testing. According to the findings of this study, specimens with a stand-off distance of 100 mm and a post-heat treatment temperature of 700oC produce the best coating qualities when compared to other specimens. This specimen resulted in a percentage of porosity and unmelted material, thickness, hardness, adhesive strength, and total wear rate of 7.1%, 5.53 x 10-1 mm, 1460 HV, 24.86 MPa, and 3.8 x10-4 mm3/s, respectively

Biodegradation of polylactic acid-based bio composites reinforced with chitosan and essential oils as anti-microbial material for food packaging

This study aims to produce and investigate the potential of biodegradable Polylactic Acid (PLA)-based composites mixed with chitosan and Turmeric Essential Oil (TEO) as an anti-microbial biomaterial. PLA has good barrier properties for moisture, so it is suitable for use as a raw material for making packaging and is included in the GRAS (Generally Recognized As Safe). Chitosan is a non-toxic and antibacterial cationic polysaccharide that needs to be improved in its ability to fight microbes. TEO must be added to increase antibacterial properties due to a large number of hydroxyl (-OH) and carbonyl functional groups. The samples were prepared in three different variations: 2 g of chitosan, 0 mL TEO and 0 mL glycerol (Biofilm 1), 3 g of chitosan, 0.3 mL TEO and 0.5 mL of glycerol (Biofilm 2), and 4 g of chitosan, 0.3 of TEO and 0.5 mL of glycerol (Biofilm 3). The final product was characterized by its functional group through Fourier transform infrared (FTIR); the functional groups contained by the addition of TEO are C-H, C=O, O-H, and N-H with the extraction method, and as indicated by the emergence of a wide band at 3503 cm−1, turmeric essential oil interacts with the polymer matrix by creating intermolecular hydrogen bonds between their terminal hydroxyl group and the carbonyl groups of the ester moieties of both PLA and Chitosan. Thermogravimetric analysis (TGA) of PLA as biofilms, the maximum temperature of a biofilm was observed at 315.74◦ C in the variation of 4 g chitosan, 0.3 mL TEO, and 0.5 mL glycerol (Biofilm 3). Morphological conditions analyzed under scanning electron microscopy (SEM) showed that the addition of TEO inside the chitosan interlayer bound chitosan molecules to produce solid particles. Chitosan and TEO showed increased anti-bacterial activity in the anti-microbial test. Furthermore, after 12 days of exposure to open areas, the biofilms generated were able to resist S. aureus and E. coli bacteria