Advances in Science and Technology Vol. 169

Abstract: In this work, the infill parameters of fabricated samples of additively manufactured PEEK using FFF is analyzed and an optimized model of ANFIS tends to predict the tensile strength of printed part. The goal is to get the best “trade-off” between minimizing the amount of printing time and printed material and maximizing tensile strength. This is done through experimentation understanding the contribution of the combination of three infill type (IP): Gyroid, Line, and Tri-hexagon and three infill density (ID): 30, 50, and 70% to the tensile strength of the printed part. An Adaptive Neuro-Fuzzy Inference System (ANFIS) is used to model the non-linear relationship between the two input and output factors. ANFIS combines the strength of both neural networks and fuzzy logic properties, the purpose is to leverage the learning capabilities of neural networks in defining complex rules for the fuzzy inference system. One-hot encoding is used to convert IP, categorical to numerical data. The generated FIS structure with grid partition of [3, 3] with gaussian membership function with a total of 15 rules. The FIS model is trained, tested, and checked with an RMSE of 2.2383, 1.0298, and 1.4846 respectively and coefficient of correlation of 0.8958. The ANFIS surface plot suggests two optimal points, both for Line IP and with two ID of 35% and 55% yielding approximately around 40 MPa and 50 MPa.

Abstract: Biocomposites are of great interest today in the development of fused filament fabrication (FFF) 3D printing filament. The hydrophilic nature of natural fibers limits the reaction between the polymer matrix and the fiber which has driven researchers to search for alternatives. Traditional methods such as injection molding have proven that polylactic acid (PLA) and peanut hull (PH) can be combined. However, producing a good combination of PLA and biocomposites remains a challenge. In this work, the combination of PLA and PH using a twin-extruder to create a FFF 3D printer compatible filament was explored. The highest yield strength of the combination is 70 wt.% PLA and 30 wt.% PH. The average tensile strength and flexural strength produced by PLA/PH is 16.239 MPa and 25.7299 MPa. Using the differential scanning calorimetry and thermogravimetric analysis the composite indicated a reduction in tensile and flexural strength. The mix has a glass transition temperature of 58.92 °C, which is lower than other composites, thus giving faster degradation. These findings demonstrate the feasibility of incorporating PH into PLA, although further optimization is needed to improve the mechanical and thermal stability of the resulting biocomposite filament.

Abstract: The powder bed fusion with electron beam (PBF-EB) process is characterised by a preheating step that keeps the building temperature high and produces partial sintering of the metallic powder particles. The influence of the preheating parameters can be studied through numerical simulations, such as those conducted with the phase field (PF) method. PF can describe the neck formation among the particles under the sintering mechanisms. In this regard, PF simulations usually account for the diffusion mechanisms only, neglecting the rigid body motion (RBM), particularly during PBF-EB. The current work analyses the effect of RBM on neck formation and growth among particles subjected to the typical working conditions of a PBF-EB. Owing to the lack of literature, the parameters that describe the rigid translation of the particles undergoing the sintering are identified using a structured design of numerical experiment. Including the RBM during sintering produces a larger neck among the particles and faster densification. This result has been found in agreement with the current literature. However, the decision to include or not the RBM should be adequately waited, considering that in the current study including RBM increased the simulation time. The results revealed that each parameter plays a different role in the rigid translation of the particles, causing a different neck dimension.

Abstract: Power generation components that operating under extreme conditions are susceptible to creep deformation. Such components rely on comprehensive creep data to ensure its integrity, smooth plant operation, and avoid fatal accident due components catastrophic failure. The small punch creep (SPC) test has emerged as a promising alternative to traditional uniaxial creep testing (UCT), offering advantages in terms of the small amount of material required for test sample. This study aims to develop a cost-effective SPC test rig integrated with an existing UCT machine and investigate its reliability in predicting the creep properties. Comparative analysis establishes a robust correlation factor (Ψ=2.5) between SPC and UCT data for Grade 91 steel at 600°C, enabling accurate estimation of creep rupture life across a broad stress spectrum. Fractographic investigations reveal the transition from ductile to brittle fracture as load levels decrease. The successful of SPC rig development and validation not only expands the creep testing toolset but also enables more efficient material characterization, optimized component design, and improved life prediction methodologies.

Abstract: In this study, a disk caster to cast thin bars was proposed and assembled, and the test casting of thin bars was carried out. The disk caster consists of a casting disk, a dam disk, and a tundish. A groove was machined on the side of the casting disk and, enclosed by the dam disk, acted as a mold in which to cast the bar. The diameters of the casting and the dam disks were 600 and 400 mm, respectively, and the cross-sectional area of the groove was 59.5 mm2. The casting speed was varied from 4 to 10 m/min. Molten Al–5%Mg was poured into the groove from the tundish. The groove was filled by the molten metal, and the bar could be cast continuously. The effect of the rotation speed of the dam disk on the casting of the bar was investigated.

Abstract: A melt drag twin-roll caster (MDTRC) was designed to convert vertical burrs at strip edges to horizontal burrs. A prototype MDTRC was assembled and tested. The forming roll is inclined frontward relative to the top of the solidification roll. Aluminum alloy strips were cast at a higher roll speed and lower roll load than what can be achieved with the conventional twin-roll caster for aluminum alloys. A semisolid layer which exists on the solidifying layer by a lower roll was formed and solidified using an upper roll. In this study, the formability of the semisolid layer and formation of horizontal burrs were investigated.

Abstract: Abrasive water jet surface cleaning technology offers advantages such as low energy consumption, high cleaning rate, and cost-effectiveness. It can effectively meet the surface cleaning requirements of complex curved metal parts and composite materials, presenting promising applications in the fields of remanufacturing and precision machining. This study specifically focuses on the design of an abrasive water jet surface coating removal device for metal structural components. To address the issue of abrasive jet wear on sealing structures, a rotating pipeline approach is employed. This innovative device allows for adjustments in the jet incidence angle and rotation radius. A simulation model is developed to predict removal rates by MATLAB/Simulink. And an experimental system is established to validate the functionality of the removal actuator, demonstrating a maximum removal rate of 34.2mm²/s at jet pressure of 5 MPa. This research contributes to enhancing the efficiency of removing surface coatings from structural components and provides valuable theoretical guidance for the planning of coating removal paths for actuators.

Abstract: Many engine development is done to achieve better engine performance, exhaust gas emissions, and engine combustion characteristics to fulfil strict regulation requirements. However, known modifications require a high cost of development. This study focuses on implementing cost-effective modification, which is the installation of Exhaust Gas Recirculation (EGR). There were three stages of the modifications made: the installation of the EGR component, air intake tank, swirls generator, and the combination of the three modifications. EGR aims to reduce harmful emissions by recirculating the exhaust gas in the catalyser into the intake manifold in a smaller quantity. The air intake tank system was installed to reduce the air intake pressure and act as a warm air reservoir collected by repositioning a high-performance air filter in front of the radiator. Lastly, a swirl generator was mounted at the air intake manifold to better blend the air-to-fuel mixture. Each modification, including the combination of all modifications, was compared with baseline emissions data, which are carbon dioxide (CO₂), carbon monoxide (CO), and nitrogen oxides (NOx). Despite the increment of the CO of as much as 42.5%, the CO₂ increased by as much as 16.3% because the combustion is near the stoichiometric combustion. The NOx can only be reduced by installing the air intake tank upstream of the intake system. The experimental result can be concluded that all the modifications implemented on the engine had made combustion towards the complete combustion process, which has lower CO and increased CO₂.

Abstract: Turbulent flow characteristics through a three-dimensional annular diffuser having a rectangular twisted hub RTH are investigated. The numerical analyses are performed to have more understanding of the physical behavior of the fluid flow. The numerical work is conducted using the RTH with three twist ratios (y/w = 0.6, 0.7, and 1) for a Reynolds number 128069. In the present study, the air is used as a working fluid. Computational Fluid Dynamics CFD, based on a finite volume method, is completed by utilizing the standard k-ε turbulence model. Velocity streamlines, velocity contours, and pressure contours plots are described to study the flow characteristics by utilizing different twist ratios (y\w). The analytical results reveal that RTH has a significant effect on the velocity and pressure characteristics. Findings show that the diffuser with the twist ratio (y\w = 0.6) produces more swirling and recirculation than (y\w = 0.7 and 1). Therefore, the RTH with a small twist ratio significantly enhances the distribution of the velocity and pressure because of the strong swirling generated through the flow.