Mechanical Engineering for Society and Industry

Carboxymethyl cellulose films derived from pineapple waste: Fabrication and properties

Heru Suryanto — 2025-01-12

Plastic waste poses a significant environmental challenge due to its non-biodegradable nature, emphasizing the need for sustainable alternatives like bioplastics from natural resources. This study develops and characterizes bioplastic films made from carboxymethyl cellulose (CMC) derived from bacterial cellulose synthesized using pineapple biowaste. Pineapple waste underwent fermentation to produce bacterial cellulose, which was chemically modified into CMC. Films were fabricated using CMC solutions with varying glycerol concentrations (0.5%, 1.0%, 1.5%, and 2.5% v/v). Characterization techniques, including SEM, XRD, FTIR, TGA, mechanical testing, and antibacterial assays, revealed that increasing glycerol concentrations smoothed the film's cross-sectional morphology, reduced crystallinity, and altered functional groups (e.g., new peaks at 870 cm⁻¹ and 935 cm⁻¹ attributed to C–H deformation). TGA indicated a four-stage thermal degradation pattern, with mass loss increasing from 77.2% to 88.4% at 2.5% glycerol, reflecting enhanced plasticization. Mechanical testing showed that the highest glycerol concentration increased film flexibility by 40.7 times while reducing tensile strength by 89.7%. Antibacterial activity against E. coli and S. aureus also improved with glycerol content. These results demonstrate the potential of CMC-based bioplastic films as sustainable packaging materials, offering customizable properties and promoting the value-added use of agricultural waste.

Design, fabrication, and performance testing of an energy storage and return (ESAR) foot prosthesis made of prepreg carbon composite

Rifky Ismail — 2025-01-14

The high demand for prosthetics in Indonesia is not followed by the ability and quality of local production to fulfill the community's needs. There is a lack of comprehensive data regarding the specific challenges encountered by local prosthetic manufacturers in Indonesia, particularly in terms of technological limitations. This study aims to understand the effect of design parameters on the performance of the energy storage and return (ESAR) foot prosthesis prototype in normal walking activities for amputees. Three different designs were created according to commercial products, and a convergence test was conducted to ensure accurate results. Finite element method (FEM) analysis was used to determine the amount of deformation that occurred in each design made when applied with 824 N axial force. The ESAR foot prosthesis prototype made from carbon prepreg was fabricated using an out-of-autoclave method, and the mechanical testing was performed with a compressive test. The results indicated that the optimal design for the ESAR foot prosthesis determined by the decision matrix scoring criteria was Design 3. The final scores for Designs 1, 2, and 3 were 54, 53, and 77, respectively. Design 3 is the easiest to manufacture, has the slightest complexity, and the lightest mass, and undergoes the least deformation during simulation, although it is the least attractive. The study found a significant difference in displacement between the deflections obtained from simulation and experiment. This occurred because the prototype was found to have delamination, which decreased the load-bearing ability of the prototype during compressive testing. Compressive testing on the prototype yielded a deflection of 22.695 mm in heel strike and 18.065 mm in toe-off positions, while FEM analysis showed 16.377 mm and 3.912 mm. Therefore, strict quality control is essential, especially when using materials such as carbon prepreg, which are prone to delamination if not properly processed.

The effect of ignition timing on engine performance in a laser ignition engine: A CFD study

Turan Alp Arslan — 2025-01-15

As a result of the high-power output, low fuel consumption, and low emissions expected from internal combustion engines, new engine technologies continue to be developed. Laser ignition systems are a solution to these expectations with the advantages they offer. Experimental and numerical studies related to laser ignition systems are accelerating today. In this study, an internal combustion engine was simulated with the spark and laser ignition systems, and the changes in engine performance for different ignition timings were investigated comparatively. ANSYS Fluent 2021 R1 software was used in the dynamic CFD study in which the entire engine cycle was analysed. Analyses were carried out at constant engine speed with an iso-octane+air mixture. Critical parameters such as pressure, volume, and temperature changes, power, torque, IMEP, MPRR, peak pressure, HRR, CHRR, start of combustion, and combustion duration were evaluated for both ignition systems. As a result of the study, optimum performance values were obtained at 680 °CA ignition timing with laser ignition system. At this ignition timing, power, torque, IMEP, MPRR, and peak pressure values were determined as 16.4302 kW, 62.7635 Nm, 14.1743 bar, 2.4665 bar/°CA, and 61.5611 bar, respectively. The laser ignition system increased engine performance, and smoother and knock-free combustion occurred. At optimum ignition timing, combustion duration was shortened, and in-cylinder temperatures decreased. The findings show that the laser ignition system will contribute to engine development studies by positively affecting engine and combustion performance.

Mechanical properties of biocomposite from polylactic acid and natural fiber and its application: A Review study

Mochamad Asrofi — 2025-02-03

In the past decade, the development of biocomposite materials has attracted much attention due to the growing concerns about petroleum-based natural resource depletion and pollution. Among the various biocomposite materials, polylactic acid (PLA) is one of the most widely produced and ideal for use in commercial products. The manufacture of PLA biocomposites with natural fiber reinforcement as an alternative material that replaces synthetic materials is widely researched. The different types of natural fiber sources used in the incorporation of matrix and fibers are very important as they affect the mechanical properties of the biocomposites. In addition, PLA-based biocomposites can be produced by a wide variety of methods that can be found in various commercializations. This study aims to present the recent developments and studies carried out on the development of PLA-based natural fiber biocomposites over the past few years. This study discusses PLA biocomposite research related to their potential, mechanical properties, some manufacturing processes, applications, challenges, and prospects.

Effect of friction reducing devices on wellbore formation

Rini Setiati — 2025-03-09

Friction is one of the unavoidable factors during drilling. If not properly managed, it can significantly reduce the rate of penetration (ROP), especially in horizontal wells. This research aims to examine the effectiveness of the Friction Reduction Tool (FRT) in managing friction without causing damage to the formation. The FRT is designed to reduce friction between the drill string and the wellbore by minimizing contact. However, its performance is often influenced by two main factors: formation characteristics and drilling parameters. This study analyzes Well X-4, which was drilled without FRT, and Well X-5, which was drilled with FRT from a depth of 2837 m (MD). The analysis focuses on the tool’s impact on stick-slip issues, ROP, and mechanical specific energy (MSE). The results indicate that the use of FRT reduced stick-slip levels and MSE, enabling the drill bit to penetrate the formation more easily. Additionally, activating the FRT from the start increased the penetration rate by 18% compared to drilling without it. These findings suggest that the FRT effectively enhances the drilling rate while preserving the formation integrity.

Robust SVM optimization using PSO and ACO for accurate lithium-ion battery health monitoring

Mufti Reza Aulia Putra — 2025-03-09

The increasing demand for reliable lithium-ion battery in various applications is focused on the need for accurate State of Health (SOH) predictions to prevent performance degradation and potential safety risks. Therefore, this research aimed to improve the accuracy of SOH prediction by integrating Particle Swarm Optimization (PSO) and Ant Colony Optimization (ACO) with Support Vector Machine (SVM) to overcome the overfitting problem in traditional machine learning models. The dataset used consisted of data from 1000 cycles of lithium-ion battery, collected under laboratory conditions. Data from lithium-ion battery cycles were analyzed using optimized PSO-SVM and ACO-SVM models. These models were evaluated using Mean Square Error (MSE) and Root Mean Square Error (RMSE) metrics, showing significant improvements in prediction accuracy and model generalization. The results showed that although both optimized models were superior to the baseline SVM, PSO-SVM had higher generalization performance during testing. The higher performance was due to the effective balance between exploring the search space and exploiting optimal solutions, making it more suitable for real-world applications. In comparison, ACO-SVM showed superior performance in training data accuracy but was more prone to overfitting, suggesting the potential for scenarios prioritizing high training accuracy. These results could be applied to extend the lifespan of lithium-ion battery, contributing to enhanced reliability and cost-effectiveness in applications.

Effect of windmill blade variations on the performance of piezoelectric energy harvesters: Enhancing vibration stability and power generation

Adhes Gamayel — 2025-03-09

Piezoelectric energy harvesters (PEHs) are gaining attention for their ability to generate electrical energy from environmental vibrations, with applications in various industries. This study focuses on optimizing the performance of a PEH using a cantilever system driven by wind energy through the impact of windmill blades. The objective is to evaluate how the number of windmill blades affects the PEH's voltage output and vibration stability. Experiments were conducted in a wind tunnel with a 250 mm × 250 mm cross-section equipped with a 12-inch blower to generate airflow. Three windmill configurations—3 blades, 4 blades, and 5 blades—were analyzed for output voltage and deflection of two PVDF-based PEHs placed at a 30° angle. Results indicate that the 3-blade configuration produced the highest voltage (1.79V), 4% and 43% higher than the 4-blade (1.71V) and 5-blade (1.01V) configurations, respectively. This configuration also exhibited maximum deflection and lower frequency vibrations. Increasing blade count led to higher frequency vibrations but reduced deflection and voltage output. The study highlights that fewer blades result in greater deflection and better energy harvesting performance. These findings contribute to ongoing research in PEH systems, offering insights into optimizing energy harvesting from fluctuating wind conditions by balancing deflection amplitude and vibration frequency.

Evaluation of corrosion mitigation of SS904l using inhibitors with statistical and morphological analysis

Dinesh Kumar Vairavel — 2025-03-09

This study evaluates the corrosion resistance of SS904L stainless steel, a highly alloyed material known for its exceptional performance in acidic environments, to address the need for optimized corrosion mitigation strategies. Corrosion inhibitors were utilized to enhance the material's durability, with the weight loss method employed to assess corrosion under varying conditions of temperature and pressure. Experiments tested inhibitor concentrations ranging from 0–5 mg per 100 mL over exposure durations of 24, 48, and 72 hours. Statistical analyses using ANOVA and regression confirmed a significant improvement in corrosion resistance with appropriate inhibitor concentrations. The Kesternich test provided comparative insights into the corrosion rate, validating the inhibitors' efficacy under simulated harsh conditions. Morphological analyses via X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) revealed the formation of protective layers on the metal surface, contributing to enhanced durability. These findings emphasize the critical role of corrosion inhibitors in extending the service life of SS904L and establish a relationship between inhibitor concentration, exposure time, and corrosion performance, paving the way for advanced corrosion mitigation strategies.

A Review on challenges and opportunities in wire arc additive manufacturing of aluminium alloys: Specific context of 7xxx series alloys

Dinesh Wasudeo Rathod — 2025-03-09

Wire arc additive manufacturing (WAAM) has emerged as a promising and cost-effective method for producing components made from aluminum alloys, particularly in industries like aviation and aerospace. This process enables the fabrication of high-performance parts while minimizing manufacturing complexities. The demand for aluminum 7xxx series alloys is significant in these sectors due to their outstanding material properties. Efficient production methods, such as WAAM, are essential for utilizing these high-demand materials effectively. Despite the advantages of the WAAM process, challenges remain, particularly when layer-by-layer deposition of Al 7xxx (Al-Zn-Mg) alloys is considered. The high heat density generated during the arcing process can lead to issues such as zinc evaporation, hydrogen formation, and oxidation of the alloys. Additionally, the WAAM technique faces hurdles like delamination, porosity, hot cracking, and complex thermal cycles, all of which can adversely affect the performance of the components produced. This study aims to tackle the challenges associated with the WAAM process by employing Gas Metal Arc Welding techniques, while also exploring opportunities for further research in this area.

Combustion characteristics of pyrolysis oil droplets from pyrolysis of polyethylene (PE) plastic waste

Dody Bimo Aji — 2025-03-09

Plastic waste is suspected to be a major contributor to environmental pollution, thus encouraging the need for innovative and effective management strategies to overcome it. Pyrolysis is considered an affordable way to process plastic waste, and even produce useful products in liquid form, which has the potential to be an alternative fuel in combustion engines. This study evaluated the combustion characteristics of pyrolysis oil derived from polyethylene (PE) plastic waste. The pyrolysis process was carried out under controlled conditions, at a furnace temperature of 250°C, a reactor temperature of 400°C, and a condenser temperature of 300°C, processing 1 kg of PE plastic waste. Temperature data was monitored every 10 minutes by installing several thermocouples. The pyrolysis process was able to produce 671 ml of liquid, which was later identified as plastic pyrolysis oil (PPO PE-11) and the rest in the form of residue reached 45 g. The results indicated that PPO PE-11 has a viscosity of 5.93 mm²/s, which is higher than diesel 3.8173 mm²/s. Meanwhile, its density is 0.779 kg/m³, which is slightly lower than diesel. The calorific value of PPO PE-11 is slightly higher than diesel, reaching 11,046.4 cal/g. The droplet scale combustion tests give a shorter ignition delay of 0.6 seconds at 41.28°C for PPO PE-11, compared to 1 second at 52.525°C for diesel, indicating its flammability.

Development of hybrid nanofluids and solar heat exchangers (SHX) to improve heat transfer performance in solar panel cooling

Amri Abdulah — 2025-03-09

This study examined the thermohydraulic efficiency of a novel Solar Heat Exchanger (SHX) designed for cooling solar panels. The SHX was specifically created for 20 Wp solar panels measuring 450 × 350 mm. The cooling medium was a hybrid nanofluid (HNF) consisting of Al₂O₃ and SiO₂ nanoparticles (0.5–1%) suspended in a base fluid of ethylene glycol and water (EG/W) at a 10:90 ratio. Experiments were performed using flow rates ranging from 1 to 3 LPM. The HNF coolant demonstrated enhanced performance in the solar heat exchanger, with a maximum heat transfer rate increase of 56.07% compared with that of the base fluid. This improvement in the heat-transfer rate was associated with an increase in the heat-transfer coefficient, which was influenced by the flow rate and volume fraction of the HNF. The effectiveness of the HNF surpassed that of the base fluids by approximately 117%. The results indicated that higher flow rates and volume fractions improved cooling performance. The enhanced cooling efficiency and innovative SHX design make this study particularly relevant to the development of solar panel cooling systems, particularly those employing hybrid nanofluid coolants.

Temperature and material flow in one-step double-acting friction stir welding process of aluminum alloy: Modeling and experimental

Eko Prasetya Budiana — 2025-04-15

Aluminum, known for its lower density compared to steel, is widely used in various applications. Welding is often required to form aluminum into technical structures. However, when fusion welding is used, it can lead to porosity in the weld. This occurs due to the significant difference in hydrogen gas solubility between liquid and solid aluminum, which traps hydrogen gas within the weld metal. Friction Stir Welding (FSW), a solid-state welding technique, has been proven to minimize porosity. However, for thick structures, FSW poses challenges, as welding must be done on both sides, increasing the welding time. To overcome this limitation, FSW has been modified into a one-step double-side FSW process, where two tools simultaneously work on both surfaces of the workpiece. This creates a unique condition with two heat sources and two stirring motion sources. To understand the temperature distribution and material flow in this process, modeling was conducted using Computational Fluid Dynamics (CFD). The upper and lower tools in the one-step double-side FSW process operate under identical conditions: a rotation speed of 1500 rpm, a welding speed of 30 mm/min, and a tilt angle of 0 degrees. The aluminum plate is treated as fluid, while the tools are considered solid in the model. The results of the temperature distribution modeling were validated against published studies, and the material flow was verified through macro- and microstructural observations of the cross-section. The validation showed that the model is accurate, with an error of only 4.07%.

Advanced computational techniques for predicting 3D printing distortion in selective laser melting processes of Aluminium AlSi10Mg

Moch. Agus Choiron — 2025-06-27

Distortion for 3D printing using Selective Laser Melting (SLM) on AlSi10Mg aluminium is an important issue that affects the final manufactured product. This research aims to develop a finite element method (FEM)-based computational simulation and experimental validation to predict distortion in 3D printed products using SLM. The study results found that the variation of 3D printing position affects the resulting product's distortion and mechanical properties. The 90° part print position results in smaller distortion of 0.303 and 0.335 mm than the 0° part print position of 0.329 and 0.378, respectively, making it more suitable for high-precision applications. This study confirms the importance of scan orientation in controlling distortion in the SLM process, which can be used as a guide for optimal printing parameters. With proper orientation selection, the risk of distortion or defects in SLM products can be minimised, and industrial production efficiency can be improved.

The analysis of semiconducting charateristic of rice husk-based carbon nanomaterial bio-activated by pineapple peel juice

Ni Made Dwidiani — 2025-06-27

This study investigates the synthesis and characterization of semiconducting materials derived from rice husk bio-activated by pineapple peel juice, presenting an eco-friendly and sustainable approach. The organic photo-active semiconducting material from rice husk ash (RHA) is synthesized. RHA was activated by immersion in the pineapple juice solution. Distinct structural disparities among RHA, Sunken Carbon nanomaterial (SCNM), and Floating Carbon Nanomaterial (FCNM) materials are revealed through SEM imaging, showcasing the tailored nature of each material. The SEM images also indicate the role of bromelain from the pineapple juice to provide defects on the RHA carbon surface. The crack on the nano particles on the surface of SCNM and FCNM were formed due to the bromelain electrostatic interaction with the surface. Elemental analysis indicates a higher probability of CuO and Si presence in SCNM, suggesting its potential for semiconductor extraction. The Cu to Si ratio implies photoactivity, confirmed by UV-Vis characterization showing absorption peaks in the UV region. FTIR analysis highlights enhanced polar interactions in SCNM and FCNM, attributed to the activation process involving bromelain in pineapple juice. The photoelectric effect testing shows FCNM and SCNM generates more electrical current as exposed to light which. The current was generated due to the electron transport phenomenon of CuO and Si content triggered by photons. The study provides insights into the materials' molecular structures and potential applications in sensors, energy devices, and semiconductor-related technologies, leveraging the unique properties of bio-derived nanomaterials for practical implementation.

Stress distribution on the L1/L2 endplates under multiaxial loads: A finite element study

Hasyid Ahmad Wicaksono — 2025-06-27

Understanding stress distribution on lumbar vertebral endplates is essential for predicting mechanical failure and guiding clinical interventions. Therefore, this study aims to investigate the von Mises stress patterns on the L1/L2 endplates under multiaxial loading using a 3-dimensional finite element (FE) model derived from CT imaging of a healthy 55-year-old male. Anatomical structures were reconstructed in Mimics 21.0, and simulations were conducted in ANSYS Workbench 2023 R2. Material properties for cortical bone, cancellous bone, and intervertebral disc were assigned based on validated biomechanical data. A compressive load of 500 N and multiaxial moments ranging from 2.5 to 10 N•m were applied to simulate physiological movements, while the inferior surface of L2 was fully constrained to reflect realistic boundary conditions. The results showed that the superior endplate experienced the highest von Mises stress, particularly during flexion and lateral bending, indicating increased vulnerability to mechanical overload. Extension loading significantly reduced stress on both endplates, with a 60.54% decrease on the superior endplate and 69.17% on the inferior endplate. Stress distribution was asymmetrical and was influenced by anatomical features, such as cortical thickness and trabecular alignment. These results show the superior endplate as a biomechanically critical region prone to degeneration, emphasizing its importance in implant design, preventive strategies, and risk assessment for microfracture in high-risk populations.

Remaining useful life prognosis of low-speed slew bearing using random vector functional link

Wahyu Caesarendra — 2025-06-27

Bearings have a very important role in an industry. However, the cost of maintenance and replacement of bearings are very expensive especially for slew-bearing which operated in a very low speed. If the low-speed slew bearing shutdown suddenly, it will also cause a financial issue to the certain industries with rely on the rotating machines because the entire machine will be shut down and the production will be stop Therefore, monitoring of the low-speed slew bearing condition at all times is necessary to predict the bearing failure. There has been advance monitoring devices and systems related to the vibration condition monitoring for bearing and rotating machines, however, in certain cases those monitoring devices and systems are not sufficient. Machine learning is offered to complement and contribute in this case which aims to determine the prediction and Remaining Useful Life (RUL) of the bearing before the bearing experiences more damage. In this paper, the Random Vector Functional Link (RVFL) is used to predict RUL using low speed slew bearing data from University of Wollongong, Australia. The main evaluation matrix such as RMSE is used as an evaluation of the performance of the model used. According to the prediction results, the best modeling results are obtained using a data ratio of 80:20 and a SELU activation function that produces the best average RMSE value. The prediction value of Remaining Useful Life (RUL) of the bearing is 94.24%.

The stress corrosion cracking (SCC) susceptibility of the dissimilar ASTM A36 steels and 316L stainless steels welding in varied temperature of FeCl2

Djarot Bangun Darmadi — 2025-06-28

Obtaining perfect dissimilar welding joints, which are exposed to corrosive environments still a problem up to now. The ASTM A36 and 316L stainless steels, dissimilar metals, were joined using Capacitive Discharge Welding (CDW). The welding parameters, such as distance between metals, pressure, applied energy, and surface parameters, were kept constant. The FeCl₂ corrosive solution concentration was also kept constant at 0.5M. The temperature of the solution was controlled at varied temperatures, those are: 30 °C, 40 °C, and 50 °C, respectively. The resistance to the Stress Corrosion Cracking (SCC) load was evaluated by time to fracture for certain dead tensile loads and corrosive media. The SEM EDS data were retrieved to have a deep insight into the SCC mechanism. The results show that, with a 10 °C increase in temperature, the SCC Threshold is decreased by 40% which is supported by the data of time to failure for certain loads and also the SEM EDS.

Structural strength evaluation of a modular toddler bicycle: Frame design and material considerations for children’s progressive development

Katon Ageng Rezkita — 2025-06-29

The toddler bicycle is essential for promoting gross motor skills in early childhood development, but its usability is often limited by fixed dimensions that do not accommodate a child’s growth. This study explores the concept of modular transformability, which allows the bicycle frame to adapt to different developmental stages, enhancing functionality and supporting sustainability through reduced waste and extended usability. As children grow, their increasing weight demands a robust structural design to ensure both safety and performance. The structural strength and stability of a modular toddler bicycle frame are evaluated using numerical simulations under static loading conditions. Various frame designs and material options are analyzed for displacements and stresses, optimizing performance while maintaining safety. The findings offer insights for improving bicycle frame design and align with a circular design philosophy that prioritizes durability, adaptability, and environmental sustainability.

Eliminating compressed air leaks in production process on compressor machine using TRIZ decision making – A case study in Somaliland company

Nagib Ismail Ahmed — 2025-06-29

In Somaliland, electricity is an expensive necessity. The high expense of electricity presents challenges for industrial development in Somaliland. Existing industries must operate efficiently to survive, specifically in the manufacturing sector, which relies heavily on electrical machinery. The compressor is widely used in manufacturing to provide the air supply to production machines, including CNC machines. However, in some cases, the air supply from the compressor is not supplied efficiently due to air leakage in standby mode. This research aims to solve this issue by implementing an integrated system that reduces energy waste caused by compressed air leakage during standby mode. This research is grounded in the application of the TRIZ contradiction matrix, which identified Inventive Principle #28 (Mechanics Substitution) as a potential solution. The proposed solution was subsequently implemented and evaluated using a pilot experimental method within the context of a case study conducted at a manufacturing company located in Hargeisa, Somaliland. The result led to the successful implementation and testing of a control system that integrated the operations of the compressor machine and CNC machine. Compared to the conventional ball valve components, the new system replaced it with an automatic air control valve integrated with the CNC machine emergency button. Electricity consumption on the compressor machine was observed and calculated for twelve months before improvement and twelve months after implementing the improvements. The data was collected for a total of 24 months to compare before improvements and after improvements for each 12 months in a machine. The improvements showed a significant reduction in electricity consumption, from 10,982 kWh to 9,830 kWh representing 10.49% energy savings, and reduced electricity operating costs by SOS 605,952 (USD 1,067) in 12 months.

Investigation of discrepancies in isotropic material and structural properties in lattice frameworks

Ahmad Anas Arifin — 2025-06-29

Lattice structures have developed as a vital component in advanced engineering applications due to their superior strength-to-weight ratios and adjustable mechanical properties. This paper focuses on examining the correlation between the isotropic features of lattices at the material level and their structural performance. The research used near-isotropic Crossing-cylinder (CC)- Body Centered Cubic (BCC) cells in various orientations and sizes. Both experimental analysis and finite element analysis were used to examine the compressive strength of the structure in each orientation. The results reveal that cell orientation is important for determining failure modes and mechanical performance at the structural level. At 0°, the lattice has higher compressive strength and energy absorption due to effective load transfer via CC-aligned struts. In contrast, higher orientations (e.g., 15°, 30°, and 45°) are dominated by collapse-type failures, indicating anisotropic behavior in an otherwise isotropic design. Smaller cell sizes have more strength at lower orientations due to their higher relative density, but larger cells perform better at higher orientations.

Exploring the potential of Indonesian iron sand in the formation of iron nitride for magnetic applications

Indra Sidharta — 2025-06-30

Iron nitride is a transition metal material that exhibits ferromagnetic properties at room temperature, making it a suitable candidate for use in Soft Magnetic Composites (SMC) applications. Previous research showed that iron nitride can be synthesized using nano-sized iron oxide powder derived from processed natural iron sand through gas nitriding. Considering the abundance of iron sand in Indonesia, there is a need to carry out an investigation related to iron sand-based SMC. Therefore, this research aims to synthesize iron nitride material using the abundant natural iron sand discovered in Indonesia. This study used iron oxide material synthesized from locally obtained natural iron sand, in the form of Fe₃O₄ and Fe₂O₃. Iron oxide undergoes coprecipitation and was subsequently exposed to the gas nitriding process with a holding time of 4 hours and a gas flow of 150 mL/min in NH₃ gas. The results show that iron nitride is formed after nitriding of iron oxide powders, and the phases formed include ε-Fe₃N and γ’-Fe₄N. The synthesized material exhibits soft magnetic properties, with saturation magnetization values ranging from the highest at 75.41 emu/g and the lowest at 18.9 emu/g.

Microstructures and mechanical properties of friction stir dissimilar AA2024-O/AA6061-T6 welded joints at varying tool rotational speeds

Diana Puspita Sumarno — 2025-06-30

Friction Stir Welding (FSW) is an innovative solid-state welding technique, especially for joints of unweldable metals or even dissimilar metals. In this study, FSW processes of two dissimilar metals, namely AA2024-O and AA6061-T6, were done at different tool rotational speeds of 910, 1500, and 2280 rpm whilst the welding speed was kept constant at 30 mm/min. This research was intended to improve the mechanical properties of the dissimilar FSW joints. A cylindrical pin-equipped tool was selected, and it was tilted at an angle of 2^o during welding. Afterwards, microstructural observations, microhardness, and tensile tests were done. Results demonstrated that increasing tool rotation increased the peak temperature, accompanied by better mixing of different metals in the weld nugget zone (WNZ), hence resulting in improved microstructural homogeneity. The hardness distributions for all dissimilar FSW joints were characterized by the appearance of a high hardness region in the central part of WNZ, resulting in a peak of hardness. It was obtained that the FSW joint at 1500 rpm revealed the best ultimate tensile strength (UTS) around 170.38 MPa, which could be a result of precipitation hardening combined with a better homogeneity in WNZ.

Ballistic performance of a composite armor reinforced by alumina balls with various matrix materials: A numerical study

Agustinus Andrie Prasetyo — 2025-06-30

This study observed the ballistic performance of the composite armor reinforced by an alumina ball with various matrix materials. The investigation was conducted numerically to establish an effective design of the composite armor for protection against a 7.62 mm bullet impacting at 800 m/s speed. Al 5083, Ti-6Al-4V, Weldox 700E, and Q235 steel, along with ceramic balls acting as reinforcement, make up the composite. The simulation was set in a 3D model and performed using Abaqus finite element software. The outputs of the simulation present the residual velocity, the depth of penetration, the optimized weight-to-penetration depth ratio, and the deformation pattern. The results indicated that the composite armor with ceramic ball reinforcement produced the optimum design using a matrix of Ti-6Al-4V. The matrix with a higher Young modulus has a higher velocity decrease. The matrix with a higher plastic equivalent strength has a higher resistance to the projectile deformation, marked by mushrooming during its penetration. On the contrary, the matrix with a lower plastic equivalent strength forms a ductile hole. This work guides to determination of the optimal design of composite armor containing ceramic balls as reinforcement, considering the different matrix materials.

Corrigendum to “Experimental investigations of number of blades effect on archimedes spiral wind turbine performance” [MESI Vol. 4, No. 2 (2024) pp 198-209]

Agus Dwi Korawan — 2025-06-30

In the original article (https://doi.org/10.31603/mesi.12373), there was a mistake in Paragraph 3 (1. Introduction), Paragraph 1 (2.2.1. The archimedes spiral wind turbine (ASWT) design), Table 1 (2.2.2.Mesh generation), Paragraph 1, 2 and 3 (3.1. Experimental result) and 4. Conclusion as published. The mistake involves the use of a comma (,) instead of a period (.) and vice versa in writing numerical values, as well as missing citations. The editor and author have communicated and agreed to correct this issue to avoid misleading readers.
All corrections are provided in detail in the PDF file.