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Teknomekanik
Published by Universitas Negeri Padang
ISSN : 26219980     EISSN : 26218720     DOI : 10.24036/tm.
Core Subject : Engineering,
Mechanical Engineering
Teknomekanik is an international journal that publishes peer-reviewed research in engineering fields (miscellaneous) to the world community. Paper written collaboratively by researchers from various countries is encouraged. It aims to promote academic exchange and increase collaboration among scientists, engineers and researchers to support sustainable development goals.
Arjuna Subject : Teknik (semua kategori) - Teknik Mesin
Articles 174 Documents
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Enhancing mechanical properties of polylactic acid through the incorporation of cellulose nanocrystals for engineering plastic applications Shih-Chen Shi; Chia-Feng Hsieh; Dieter Rahmadiawan
Teknomekanik Vol. 7 No. 1 (2024): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v7i1.30072

Abstract

This study investigates the potential of enhancing the mechanical properties of polylactic acid (PLA) using cellulose nanocrystals (CNC). Recognized for their high specific strength and stiffness, CNCs are considered to improve the performance of PLA in engineering plastic applications. The synthesis involves a twin-screw extrusion process, which facilitates the uniform dispersion of CNC within the PLA matrix. The mechanical properties, including tensile strength and elongation at break, are comprehensively analyzed, highlighting the effects of CNC concentrations on the performance of PLA composites. Notably, the addition of 1 wt% CNC resulted in a 20% increase in strain at break compared to pure PLA, demonstrating enhanced ductility. Additionally, the thermal resistance of the composite increased by 0.3% with the inclusion of 5 wt% CNC. This study highlights the positive effect of CNC addition on the mechanical properties of PLA composites, making them more suitable for specialized engineering uses.
Classifying four maturity categories of coffee cherry using CNN-VGG19 Dominic Olango Cagadas; Dwi Sudarno Putra; Kristine Mae Paboreal Dunque; Meri Azmi
Teknomekanik Vol. 7 No. 2 (2024): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v7i2.31072

Abstract

The local coffee farmers employ manual inspection to identify the maturity of coffee cherries that are inefficient in labor and time. Thus, the objective of this study is to develop a CNN-VGG19 algorithm model that can accurately detect the maturity image of coffee cherry samples, and classify them into: unripe, semi-ripe, ripe, and overripe categories. The proposed solution will provide local coffee farmers with an automated and more accurate classification of the quality of coffee cherries. The visual geometry group-19 was employed to increase the object recognition model performance of the proposed algorithm while maintaining higher accuracy and quicker throughput, thus increasing revenues. The images are utilized as training and test set data. They were then processed by using the feature extraction of CNN-VGG19 deep learning model, and got four coffee cherry maturity classes. The model architecture attained a 90.00 % accuracy. Furthermore, the increase in both the validation and training accuracy graph with a corresponding decrease in both the validation and training loss graph propounds that the model performance has improved.
Infiltration capacity based on soil geophysical constants using artificial infiltration in residential land Totoh Andayono; Mas Mera; Junaidi Junaidi; Dalrino Dalrino
Teknomekanik Vol. 7 No. 2 (2024): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v7i2.31372

Abstract

Conversion of catch-land into residential land in urban areas reduces infiltration, and increases surface flow and flood risk. Artificial infiltration is a potential solution to increase infiltration capacity, but its effectiveness is highly dependent on the physical characteristics of the soil, including geophysical constants. This study aims to determine the level of infiltration capacity based on the value of soil geophysical constants using artificial infiltration in residential land in Padang. Measurements were carried out using the Horton method and double-ring infiltrometer in several residential locations. The study results show that the soil characteristics of residential land in Padang consist of the soil texture of sand, loamy sand, and sandy loam, which have high moisture content, large fill weight, and low porosity, causing low infiltration rate and high surface flow. Artificial infiltration can significantly increase the infiltration capacity, especially on sandy soils with high hydraulic conductivity. The soil geophysical constant, k, is classified according to field measurement results. In the lower range of 1.2 < k ≤ 1.9, the average infiltration capacity was found at 625.1 mm/hour. Within the interval of 1.9 < k ≤ 2.6, the mean capacity decreased to 587.7 mm/hour, but in the upper interval of 2.6 < k ≤ 3.3, the average infiltration capacity was 499 mm/hour. Large soil geophysical constants reveal higher infiltration capacity, while small geophysical constants indicate low infiltration capacity.
Transformative process: Crafting imines from nitrobenzene and benzyl alcohol coupling with cerium oxide modified mesoporous SBA-15 Soumini Chandralayam; Sugunan Sankaran
Teknomekanik Vol. 7 No. 2 (2024): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v7i2.31772

Abstract

A low-cost and eco-friendly cerium oxide modified mesoporous SBA-15 catalyst was developed by wet impregnation. It enables sequential oxidation of benzyl alcohol and reduction of nitrobenzene, followed by imine formation in a single and solvent-free system. Characterization confirms homogeneous cerium oxide dispersion, high stability, and enhanced redox properties. The optimized catalyst demonstrates excellent conversion and selectivity, attributed to the mesoporous SBA support, acidic properties, and cerium's redox functionality. Elevated temperatures enhance benzyl alcohol dehydration and hydrogen diffusion, facilitating intermediate aniline formation by a borrowing-hydrogen mechanism and followed by imine synthesis. It eliminates solvents, reduces byproducts, and achieves high atom economy and renewability. It presents a significant advance in sustainable catalysis. The catalyst's robustness and ease of recovery strengthen its practicality for repeated cycles. The findings provide a scalable and energy-efficient solution for greener imine synthesis with potential applications in industrial processes requiring efficient and eco-friendly chemical production. It ensures minimal environmental impact and offers a cost-effective pathway for high-value chemical synthesis. This study supports the SDGs by promoting sustainable industrial practices through the development of a low-cost and eco-friendly catalyst that reduces environmental impact, enhances energy efficiency, and contributes to greener chemical production.
Vapor compression refrigeration system with air and water cooled condenser: Analysis of thermodynamic behavior and energy efficiency ratio Muji Setiyo; Retno Rusdjijati; Ilham Habibi; Muhamad Latifur Rochman; Bagiyo Condro Purnomo; Fungky Dyan Pertiwi; Budi Waluyo; Rifky Ismail; Aditya Kolakoti
Teknomekanik Vol. 7 No. 2 (2024): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v7i2.31972

Abstract

This study presents the analysis of thermodynamic behavior and energy efficiency of a vapor compression refrigeration system with two types of condensers: air-cooled (ACC) and water-cooled (WCC). The main objective is to assess the system performance by comparing the Coefficient of Performance (COP) and Energy Efficiency Ratio (EER) under both condenser configurations. During a 12-hour test period, data on refrigerant pressure, temperature, and electrical energy consumption were collected and analyzed. The results show that the WCC system outperforms the ACC system, showing a 5.7% increase in heat rejection and a 4.2% increase in cooling capacity. In addition, the WCC system exhibits a lower compressor duty cycle and consumes less electrical energy, resulting in a higher total EER of 5.658 compared to ACC of 1.945. These findings suggest that integrating a water-cooled condenser into a refrigeration system can significantly improve energy efficiency and reduce operating costs, making it a viable option for commercial applications in tropical regions.
Enhanced durability and tribological performance of polyvinyl alcohol/layered double hydroxide/tannic acid composites under repeated swelling cycles Dieter Rahmadiawan; Shih-Chen Shi; Wei-Ting Zhuang; Eko Indrawan; Yolli Fernanda; Budi Syahri; Irzal Irzal
Teknomekanik Vol. 7 No. 2 (2024): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v7i2.32872

Abstract

In recent years, the exploration of polyvinyl alcohol (PVA) composites has garnered significant attention due to their versatility applications in aqueous environments. However, despite their promise, neat PVA exhibit limitations such as significant mechanical degradation under repeated swelling cycles. This study investigates the durability and tribological performance of polyvinyl alcohol (PVA) composites reinforced with nickel-iron layered double hydroxide (LDH) and tannic acid (TA) under repeated swelling cycles. Building on previous research that explored composite preparation and initial characterization, this research emphasizes the effects of cyclic swelling on wear resistance, friction behavior, and mechanical properties. Tribological tests were conducted to evaluate the coefficient of friction (COF) and wear rate before and after multiple swelling cycles, alongside tensile strength and strain measurements. The results revealed that the PVA/TA2/LDH2 composite, containing the highest additive content, exhibited the lowest wear rate of 11.52 × 10⁻⁵ mm³/Nm after 3 swelling cycles, demonstrating superior resistance to material degradation. Although PVA/TA2/LDH1 exhibited a slightly lower COF, its wear rate was higher due to reduced reinforcement. Compared to neat PVA, which showed a COF increase from 0.45 to 0.53, the PVA/LDH/TA composites retained their tribological stability, with only a marginal increase in COF and wear rate. Similarly, tensile strength of PVA/TA2/LDH2 decreased by only 11% after 3 cycles (from 33.3 MPa to 30 MPa), while neat PVA experienced a 25.5% reduction (from 30 MPa to 22.5 MPa). These findings highlight the potential of PVA/LDH/TA composites for applications in aqueous environments, offering significantly enhanced long-term performance and reliability.
The conversion of nata de coco bacterial cellulose into cellulose nanofibers using high shear mixer with eco-friendly fluid dynamics method Amun Amri; Diana Eka Putri; Dhina Febryza; Salsabilla Diva Voadi; Syelvia Putri Utami; Hussein A. Miran; M. Mahbubur Rahman
Teknomekanik Vol. 7 No. 2 (2024): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v7i2.32972

Abstract

Nanocellulose is widely applied in various fields due to its superior characteristics. Several methods have been developed to synthesize it, but they still have limitedness as being non-eco-friendly and inefficient use. Therefore, the synthesis of nanocellulose from sustainable sources is being developed using a simple and eco-friendly method. This study successfully produced a low viscosity gel suspension of cellulose nanofibers (CNF) from bacterial cellulose (BC) derived from Nata de Coco using a high shear mixer (HSM). The mixture of BC and water in a 1:1 ratio was processed with various rotational speeds and times in the HSM. The suspension result was characterized using an Ostwald viscometer, UV-vis spectrophotometer, lux meter, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), particle size analyzer (PSA), and x-ray diffraction (XRD). Based on the characterization, it was confirmed that higher rotational speeds and extended processing times reduced the suspension viscosity and increased light transmittance, indicating a reduction in BC size to the submicron/nanometer scale. The best light transmittance was achieved with the HSM at 4500 rpm for 180 min, resulting in a viscosity drop from 232.67 mPa.s to 1.45 mPa.s. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis showed that the CNF retained its fibrous structure with nanometer-scale widths and high porosity without significant changes in crystallinity.
Optimizing vertical-axis wind turbine designs: A comparative CFD analysis of savonius, darrieus, and savonius-darrieus configurations Nelvi Erizon; Refdinal Refdinal; Jasman Jasman; Irzal Irzal; Yufrizal A; Muhammad Shadiq Fahrezi; Firza Fernanda; Egi Fadillah; Ma Leona Maye B. Pepito
Teknomekanik Vol. 8 No. 2 (2025): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v8i2.33172

Abstract

This study aims to evaluate the performance of vertical-axis wind turbines (VAWTs) with three different configurations, including Savonius, Darrieus, and a Savonius-Darrieus hybrid wind turbine, using Computational Fluid Dynamics (CFD) simulations. The methodology involves 3D geometry modeling, simulation parameter setup, meshing, and post-simulation analysis using SolidWorks 2022 software. The simulation results indicate that the Savonius turbine achieves the highest power coefficient (Cp) and torque coefficient (Ct) among the three designs, with a maximum Cp value of 0.5 at a Tip-Speed Ratio (TSR) of 0.4. Conversely, the hybrid turbine demonstrates lower efficiency, although it theoretically offers potential for improving performance at low wind speeds. Pressure and flow velocity distributions reveal that the Savonius turbine maintains the most stable pressure pattern compared to the other configurations. These findings highlight the potential of the Savonius turbine as a small-scale renewable energy solution, particularly in urban areas with low wind speeds. Further research is recommended to optimize hybrid turbine designs using machine learning approaches and empirical validation through field experiments to support the achievement of Sustainable Development Goals (SDGs), particularly Goal 7, affordable and clean energy.
Natural fiber substitution in glass fiber-reinforced plastics: A Tensile properties simulation Alief Wikarta; Chandya Andikusuma; Julendra Ariatedja; I Made Londen Batan; Femiana Gapsari; Sze Wei Khoo
Teknomekanik Vol. 8 No. 1 (2025): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v8i1.33472

Abstract

Glass fiber-reinforced polymer composite materials, commonly used for industrial axial flow fan blades due to their high strength-to-weight ratio, are environmentally criticized for their non-biodegradability. This concern has prompted the investigation of eco-friendly alternatives, such as sisal and kenaf as natural fibers. Although they generally have lower mechanical properties than synthetic fibers, they offer advantages in terms of biodegradability, cost, and density. This study aims to evaluate the feasibility of partially substituting glass fiber with unidirectional natural fibers kenaf and sisal in a 14-layer GFRP axial fan blade through numerical simulation. The research employed a finite element method (FEM) to simulate tensile testing in accordance with ASTM D-638 standards. Several hybrid layer configurations were analyzed, focusing on the number and position of natural fiber layers replacing glass fiber, particularly the glass roving (GR) layers. The simulation investigated how these substitutions influence the overall tensile stress and elastic modulus of the composite blade structure. The findings suggest that this substitution does not significantly affect tensile characteristics but substantially improves the biodegradability of the composite, resulting in a more environmentally friendly material without compromising mechanical performance.
Evaluation and characterization of charcoal briquettes using damar binder for sustainable energy Hendri Nurdin; Waskito Waskito; Dani Harmanto; Purwantono Purwantono; Andre Kurniawan; Dori Yuvenda; Yoszi Mingsih Anaperta
Teknomekanik Vol. 8 No. 1 (2025): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v8i1.33672

Abstract

Palm kernel shells have great potential as biomass and renewable energy sources. Its utilization has not been maximized which is only directly burned which causes air pollution. The accumulation of solid waste in the crude palm oil processing industry negatively impacts the environment. The research aims to determine the characteristics and quality of charcoal briquettes with palm kernel shell carbonization. The main findings of this study are the calorific value, water content, volatile matter, ash content, and fixed carbon in palm kernel shell charcoal briquettes with damar binder. The experimental research method was carried out by carbonizing the raw materials of palm kernel shell briquettes, applying various concentrations of damar binder mixtures. The technical parameters of briquette making were 10 MPa pressure, 60 mesh size, and different carbonization temperatures by furnace. The calorific and proximate were empirically measured by using a bomb calorimeter. This research produced palm kernel shell charcoal briquettes with a calorific value of 30.72 MJ/kg at a carbonization temperature of 500oC and concentration of 85%:15%, a moisture content of 5.18%, volatile matter of 32.72%, ash content of 2.81%, and fixed carbon of 57.90%. Palm kernel shell charcoal briquetting technology is potentially a recommended alternative solid fuel. Consequently, developing renewable energy that is environmentally friendly leads to achieve sustainable energy security. By utilizing waste, the negative impacts on the environment can be overcome and energy needs are also resolved.

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