Scientific Journal of Mechanical Engineering Kinematika

INVESTIGATION OF MECHANICAL PROPERTIES OF SLA 3D PRINTED RESIN IN BENDING MOMENT ANALYSIS USING FINITE ELEMENT METHOD

Lita Asyriati Latif — 2026-07-15

This study investigates the mechanical properties of Stereolithography (SLA) 3D printed resin in bending moment analysis using the Finite Element Method (FEM). With the growing adoption of SLA in healthcare and manufacturing, understanding mechanical performance of SLA-printed components, particularly in bending, is crucial. The research evaluates influence of printing parameters and material composition on flexural strength and flexibility of dental resin samples. It examines internal geometries such as triangle and honeycomb structures and varying thickness-to-height ratios affecting bending strength. Bending tests followed ASTM D790 standards and results were compared with FEM simulations to validate material behavior. Simulations were performed using Abaqus Student 2025 software under conditions matching experimental tests. Results show geometry and thickness-to-height ratio significantly affect bending strength, with triangle geometry outperforming honeycomb. Samples with triangle geometry and 4.5 mm ratio achieved highest bending strength of 62.743 MPa, while honeycomb 9 mm reached 55.943 MPa. Post-processing such as UV curing improves mechanical properties of resin. This study provides insights for SLA 3D printing applications in dental prosthetics and offers a framework to optimize printing parameters for performance. It contributes to the development of predictive modeling combining FEM and experimental validation for improved design of additively manufactured resin components in biomedical applications. Future work will explore broader geometries, different resin formulations, and more complex loading conditions to enhance accuracy and reliability of simulation-based design methods for SLA printed structures in engineering and medical fields as well as improve clinical applicability in dental prosthetic fabrication processes and patient outcomes overall performance.

THE EFFECT OF GRAPHENE METAL FOAM UTILIZATION ON THE HEAT TRANSFER COEFFICIENT IN A CLOSED-LOOP GEOTHERMAL SYSTEM

Dinar Kurniawan — 2026-07-20

This study presents an experimental investigation into the effect of graphene metal foam on the heat-transfer performance of a closed-loop geothermal system. The system uses a sealed pipe configuration to circulate a low-temperature working fluid that extracts heat from the subsurface reservoir via conductive heat transfer and transports it to the surface. In this work, the system is modelled using a coaxial heat exchanger heated by an oven to simulate the geothermal reservoir. Two structural specifications of graphene-coated Ni-Fe alloy foam, 85% (90 PPI) and 90% (110 PPI), were employed and tested at a constant flow rate of 0.3 LPM under varying heat source temperatures of 170, 200, and 230 °C. The results show that both foam configurations achieved their highest performance at 230 °C. The overall heat transfer coefficient () reached 749.48 W/m².K for 85% (90 PPI) porosity and 462.78 W/m².K for 90% (110 PPI) porosity, significantly higher than that of a plain tube (103.88 W/m².K). These findings demonstrate that incorporating graphene metal foam, particularly at 85% porosity, effectively enhances heat-transfer performance in closed-loop geothermal systems.

THE EFFECTS OF ALUMINUM REFLECTOR SHAPES, ANGLES, AND THERMAL-LIGHT COVARIATION ON SOLAR PANEL PERFORMANCE

Nur Zaini Khafid — 2026-09-06

The performance of solar panels is strongly influenced by light intensity, panel temperature, and incident angle, indicating the need for reflector-based enhancements to improve power output. This study aims to analyze the effects of aluminum reflector shapes and angles on solar panel output while evaluating the covariation effects of room temperature, panel temperature, and light intensity. Experiments were conducted indoors using a 200 W spotlight with three reflector configurations (none, flat, concave) and angles of 55°, 65°, 75°, and 85°. Data were analyzed using MANCOVA and correlation tests to determine significance across variables. Results indicate that both reflector shape and angle significantly affect current and voltage, with the flat reflector delivering the highest power output, especially at a 55° angle. Light intensity was found to be the dominant covariate increasing power, whereas panel and room temperatures showed negative correlations. These findings highlight the crucial role of optimized reflector design and thermal management in enhancing solar panel performance.

EXPERIMENTAL STUDY COMPARING SHELL S3X IMMERSION COOLING AND AIR COOLING PERFORMANCE IN DATA CENTERS

Andreas Argo Daru — 2026-09-06

The efficiency with conventional air cooling systems in controlling surplus heat has reached its limits due to the growing computing load in data centers. On a server with a 100% workload, this study compares the thermal performance and energy efficiency of air cooling and single-phase immersion cooling systems. An experimental test utilized Shell S3X dielectric fluid at a steady flow rate of 1.75 LPM to simultaneously cool an Intel Xeon E-2336 CPU and an Nvidia RTX A400 GPU. The findings demonstrate that immersion cooling significantly lowered operating temperatures by 17.50% for the GPU from 80.0 °C to 66.0 °C and by 35.53% for the CPU from 76.0 °C to 49.0 °C. This performance improvement is caused by a large increase in the convective heat transfer coefficient of up to 157.37% compared to conventional air cooling, which directly reduces the system's thermal resistance by up to 60.81%. In terms of energy efficiency, immersion cooling achieved a Power Usage Effectiveness score of 1.04, compared to 1.69 for the air system, and a Cooling Performance Index of 15.76.

EXPERIMENTAL STUDY ON THE PERFORMANCE OF SINGLE-PHASE IMMERSION COOLING FOR LITHIUM-ION BATTERIES

Ivan Ardiansyah — 2026-09-06

This study experimentally investigates the thermal performance of static immersion cooling for cylindrical lithium-ion batteries using a hydrocarbon-based dielectric fluid (Shell S3 X). Natural convection (NC) and static immersion cooling were compared for two battery variants at a 3C discharge rate up to 80% depth of discharge. Results demonstrate that static immersion cooling consistently outperforms natural convection. Specifically, IC reduced the average and maximum surface temperatures by up to 11.50% and 11.93%, respectively. Furthermore, thermal uniformity improved significantly, with the maximum surface temperature difference decreasing from 3.2°C to 1.6°C for Battery A, and from 7.4°C to 5.0°C for Battery B. Energy-balance analysis confirmed a reduction in residual battery heat by up to 10.03%, accompanied by an enhanced apparent heat-transfer coefficient. These findings establish that passive immersion cooling using Shell S3 X effectively suppresses temperature rise and improves thermal uniformity, offering a promising solution for battery thermal management.

ENHANCING PHOTOVOLTAIC EFFICIENCY USING SERPENTINE LIQUID COOLING UNDER VARYING FLOW RATES IN TROPICAL CLIMATES

Bintang Arif Prasetya — 2026-09-06

Global growth in electricity demand and the environmental impact of fossil fuels have accelerated the adoption of photovoltaic (PV) technology. However, PV efficiency significantly degrades under high outdoor thermal loads, where every 1°C rise in temperature reduces efficiency by approximately 0.3-0.5%. This study evaluates an active thermal management system (TMS) based on a serpentine liquid channel integrated with a dual-axis solar tracker on a 100 Wp monocrystalline PV module. Outdoor experimental research was conducted at Universitas Gadjah Mada in April 2026. Water flow rates of 1.5 LPM and 2.5 LPM were analyzed to determine their impact on performance. To ensure a fair comparative evaluation under dynamic weather conditions, cooling performance was evaluated against an analytical non-cooled baseline calculated using standard STC coefficients driven by real-time environmental data. The results demonstrate that the TMS significantly lowered cell temperatures. At 1.5 LPM, the average temperature reduction was 12.43°C, while 2.5 LPM achieved a better reduction of 14.58°C. The heat transfer coefficient increased by 43.1%, rising from 322.77 W/m²K at 1.5 LPM to 461.89 W/m²K at 2.5 LPM. Consequently, average gross electrical efficiency improved from a non-cooled of 14.69% to 15.63% at 2.5 LPM, representing a 6.4% relative increase. While the 2.5 LPM flow rate achieved the better gross electrical efficiency, the 1.5 LPM configuration yielded slightly better net efficiency after accounting for the pump load. These findings confirm that increasing water flow rates within serpentine channels effectively maintains the PV temperature and improves its gross efficiency.