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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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Hydrodynamic optimization of a Sweptback Stern Foil for resistance reduction in flat-hull ships: A CFD-based extension of the Hull Vane concept Nabawi, Rahmat Azis; Syahri, Budi; Alfana, Yogi Dian; Fernandez, Donny
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.54872

Abstract

Flat-hull ships are known to have higher resistance than streamlined hulls. Although the Hull Vane® concept has been proven effective as a stern-mounted energy-saving device through pressure-field modification and stern-wave interaction, most previous studies have focused on straight-foil configurations (straight planform). The effect of planform shape optimization, particularly the sweptback configuration, on the hydrodynamic performance of flat-hull ships is limited in the literature. This study modifies the geometry of a Hull Vane® into a sweptback stern foil and evaluates its performance using Computational Fluid Dynamics simulations. The results show that a 15° sweptback angle yields the greatest reduction in total drag. Velocity contour analysis shows a narrower wake and a more uniform velocity-gradient distribution in the stern area for the 15° swept-back stern-foil configuration compared to other configurations. Meanwhile, the turbulence length distribution shows a tendency toward reduced intensity of large-scale turbulent structures behind the ship, indicating improved wake-flow characteristics. The identified drag reduction mechanism primarily stems from improved pressure recovery and modified pressure distribution in the stern area, which is consistent with the working principle of Hull Vane®. Optimizing the sweptback planform geometry yields more efficient flow interaction than the straight-foil configuration. These findings indicate that planform optimization is an important design parameter in the development of stern foils to improve the hydrodynamic efficiency of medium-to high-speed commercial vessels.
Multiclass gas pipeline leak detection using multi-domain signals and genetic algorithm-optimized classification models Wiwit Suprihatiningsih; Dedik Romahadi; Hadi Pranoto; Rikko Putra Youlia; Fajar Anggara; Rizky Rahmatullah
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.38372

Abstract

Pipeline networks are critical infrastructure for oil and gas transport because the occurrence of leaks can rapidly escalate into safety, economic, and environmental crises. Operators are practically required to identify the presence and type of leaks; however, applying multiclass recognition is challenging when labeled data and computing power are limited. Therefore, this study proposes a three-stage pipeline which consists of: (1) adopting the GPLA-12 dataset of acoustic or vibration signals spanning 12 leak types; (2) extracting multi-domain features by combining time-domain descriptors with Power Spectral Density (PSD)-based spectral features; and (3) applying a genetic algorithm (GA) as a wrapper for feature selection to enhance discriminability and reduce dimensionality, which was followed by benchmarking seven conventional classifiers and GA-based refinement of the top model with a focus on the feature subset and hyperparameters. A maximum accuracy of 96.35% was achieved on the GPLA-12 dataset with low computation time and a simple model architecture. The proposed pipeline also attained similar or better accuracy at substantially lower complexity and data requirements compared with prior deep CNN approaches. These results support timely multiclass decision-making in resource-constrained industrial settings. A key observation was that the focus was on supervised leak-type classification from acoustic or vibration signals, while localization, severity estimation, and multi-sensor fusion were beyond the scope of this study.
Comparative study on the corrosion behavior of TiCN-coated austenitic and ferritic stainless steels in geothermal environments Agus Solehudin; Haipan Salam; Enda Permana; Atiek Rostika Noviyanti; Akrajas Ali Umaar; Risti Ragadhita
Teknomekanik Vol. 9 No. 2 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i2.44172

Abstract

Corrosion in stainless steel (SS) remains a critical limitation for its application, particularly in harsh environments such as geothermal systems. This study aims to evaluate the corrosion resistance of two SS substrates, namely SS 11-0 (ferritic) and SS 18-8 (austenitic), used as drill bit materials, both before and after the application of a TiCN protective coating. The coating was deposited by Physical Vapor Deposition (PVD) for 15, 25, and 35 minutes at 250°C. Corrosion resistance was assessed using a salt spray test with a 5% NaCl solution (pH 6–7) for 100 hours to simulate a neutral corrosive environment. Surface morphology and elemental composition were characterized using Field Emission Scanning Electron Microscopy–Energy Dispersive X-ray Spectroscopy (FESEM–EDS), while coating thickness and hardness were evaluated using Fischerscope® X-RAY XAN and Vickers microhardness testing, respectively. Corrosion performance was quantitatively analyzed using mass-loss-based corrosion rate calculations and polarization resistance measurements with a potentiostat instrument, providing insights into the electrochemical behavior of the coating–substrate system. The results demonstrate that increasing deposition time enhances coating thickness and overall coating quality. FESEM–EDS analysis confirms the successful formation of the TiCN layer and reveals changes in surface morphology and elemental composition after coating and corrosion exposure. Among the tested substrates, SS 18-8 consistently exhibits superior hardness, surface uniformity, and corrosion resistance compared to SS 11-0. Based on the weight loss method, the corrosion rates of uncoated and TiCN-coated SS 18-8 are 0.2600 mm/year and 0.1625 mm/year, respectively, both lower than those observed for SS 11-0. This enhanced performance is attributed to the synergistic effect between the TiCN coating and the Cr- and Ni-rich chemical composition of SS 18-8, which facilitates the formation of a stable and protective passive layer. These findings highlight the strong potential of TiCN-coated SS 18-8 for applications in geothermal environments under neutral corrosive conditions.
Performance evaluation of a standalone PCA-based denoising method for Distributed Acoustic Sensing (DAS) data Monowar Mahmud; Aiman Ismail; Fairuz Abdullah; Hui Jing Lee; Nur Luqman Saleh; Abdul Hadi Sulaiman
Teknomekanik Vol. 9 No. 2 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i2.44372

Abstract

This paper experimentally evaluates the effectiveness of Principal Component Analysis (PCA) for denoising distributed acoustic sensing (DAS) data. Experiments were conducted by applying different vibration strengths using a piezo-electric transducer (PZT) at various sensing locations along the sensing fiber. Unlike existing hybrid PCA-based DAS denoising approaches, this work explicitly investigates PCA as a standalone denoising framework, addressing the lack of systematic evaluation of its effectiveness and practical applicability. Results show that PCA improves the signal-to-noise ratio (SNR) by at least 4.7 dB across a range of strain levels. The SNR also shows improvements exceeding 5 dB for sensing fiber lengths up to ~5.2 km. For ~10.2 km vibration location, PCA still achieved around 2.45 dB of SNR improvement. The PCA algorithm was then compared with traditional denoising algorithms, i.e., Moving Average, Low-Pass Filtering, and Wavelet Denoising, at a fixed sensing fiber length of 3.2 km and 2 Vpp applied to the PZT. PCA outperformed these approaches in noise reduction while maintaining moderate computational cost. Overall, PCA effectively suppresses background noise while preserving the integrity of the vibration signal. These results indicate that standalone PCA is a practical denoising option for DAS applications that require improved SNR at a moderate processing cost.
Uniaxial and biaxial hot pressing of PVDF films: A pathway toward high-performance piezoelectric sensors and energy harvesters Suprapto Suprapto; Jubaidah jubaidah; Selamat Triono; Harianto Gunawan; Lisyanto Lisyanto; Aditya Sukma Nugraha; Yopan rahmad Aldori
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.44972

Abstract

The piezoelectric efficiency of Poly (vinylidene fluoride) (PVDF) membranes becomes restricted by the challenge of generating and stabilizing electroactive β-phase during processing. Stretching requires control of deformation parameter, while solvent-based methods bring environmental and occupational health risks. This research suggests hot-pressing as an alternative method for enhancing β-phase fraction, utilizing multidirectional stress without solvent or chemical exposure. This study systematically compares uniaxial hot-pressing (Uniaxial HP) and biaxial hot-pressing (Biaxial HP) setups to determine which stress distribution is more effective at promoting changes and improving piezoelectric properties in PVDF membranes. The main objective of this research is to systematically evaluate and compare the impacts of uniaxial and biaxial hot-pressing on the crystalline phase transformation and electromechanical performance, including the piezoelectric coefficient (d33) and output voltage response of PVDF membranes. PVDF pellets were hot-pressed at 220o C under a pressure of 60 MPa for 15 minutes followed by rapid quenching in ice water. X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) confirmed phase composition, correlated with performance via the piezoelectric coefficient (d33), and assessed piezoelectric activity. Experimental results show that biaxial loading provides a higher b-phase fraction (50.47%) compared to untreated membranes (47.80%) and UHP samples (49.30%). The crystallinity and the piezoelectric coefficient also increased to 49% and 18.8 pC/N, respectively. Biaxial stress pattern during hot-pressing induces favourable thermodynamic and kinetic conditions for b-phase expansion. Beyond phase-related results, the approach delivers competitive piezoelectric effectiveness while maintaining simplicity and reducing solvent-dependent processing steps.
Grid convergence analysis of an H-Darrieus wind turbine for multiple blade configurations Sanjaya Baroar Sakti Nasution; Dian Morfi Nasution; Elang Pramudya Wijaya; Oki Suprada Ompusunggu
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.45272

Abstract

Mesh size and number significantly affected the accuracy of CFD simulations in wind turbine analysis. However, most studies focused solely on turbine performance, such as the blade torque or power coefficients. Therefore, this study adopted a broader perspective by analyzing the influence of mesh resolution on both aerodynamic performance and key fluid-dynamic parameters, including vorticity and pressure coefficients, for an H-type Darrieus vertical-axis wind turbine. Two-dimensional CFD simulations were performed using ANSYS Fluent with the k–ω SST turbulence model. Five mesh levels were evaluated across different blade configurations, and the Grid Convergence Index (GCI) was used to quantify discretization errors. The results indicate that increasing mesh resolution yields more stable torque predictions and improved resolution of near-wall flow features, with consistent grid-convergence behaviour observed across all blade configurations. GCI analysis shows that discretization errors consistently decrease as the mesh becomes finer. It also shows that a grid size of about 1.6 x 105 cells is sufficient to keep errors below 5%. These findings show that including flow-field details in mesh sensitivity analysis gives a better way to check the accuracy of CFD simulations for Darrieus wind turbines.
Comparative analysis of bio-inspired and topology-optimized lattices under compressive loading Ahmad Anas Arifin; I Made Londen Batan; Michele Bici; Arif Wahjudi; Agus Sigit Pramono
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.45472

Abstract

Lattice structure design is still dominated by strut-based forms and surface-based shapes, such as triply periodic minimal surfaces (TPMS), which both exhibit overlapping limitations. Strut lattices often show strong anisotropy because their response depends heavily on cell orientation, while TPMS lattices are difficult to adjust when bounded by geometric constraints. These conditions eventually led to stagnation in the development of lattice morphology. Hybrid and topology-optimization methods have appeared as possible alternatives, but many of them still produce modified versions of classical patterns. This study examined two lattice geometries: the Pyramorph, inspired by the shape of a pyramid, and the Topomorph, generated through a topology optimization framework. Both structures were designed using a CAD unit cell patterning technique and manufactured using the FDM method, with relative densities ranging from 0.40 to 0.44. Their mechanical behaviour was examined through FEA simulation and uniaxial compression testing. The parameter variations included cell orientations of 0°, 15°, 30°, and 45°, and cell sizes of 8 mm and 12 mm within a 24 mm specimen. The Topomorph showed superior strength, reaching 15–20 MPa, while the Pyramorph reached only 7–8 MPa. The highest value, about 20.5 MPa, was obtained from the Topomorph at 0° and with an 8 mm cell size. Failure modes indicated buckling and delamination in the Pyramorph, while the Topomorph tended to collapse progressively. These findings indicate that topology optimization combined with CAD-based patterning could significantly improve lattice performance.
Effects of process parameters on the evaporative pattern casting of scrap aluminum–RHA composites Rudi Siswanto; Abdul Ghofur; Rachmat Subagyo; Mastiadi Tamjidillah; Mahmud Mahmud; Ma’ruf Ma’ruf; Adi Nordiman
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.46072

Abstract

This study investigates the fabrication and characterization of aluminium matrix composites reinforced with rice husk ash (RHA), using scrap aluminium as the base material and evaporative pattern casting as the manufacturing method. The work evaluates the effects of three key independent variables: pouring temperature, aluminium (Al)-RHA composition ratios, and styrofoam pattern thickness on the resulting composite properties. The dependent variables examined include surface roughness, Brinell hardness, and dimensional shrinkage-expansion. Experimental results show that increasing the pouring temperature and adjusting the composition ratio significantly influence the mechanical and physical properties of the composites. The highest hardness (45.6 HB) and fluidity (252.65 mm) were achieved at a 60:40 composition ratio and a pouring temperature of 750 °C, albeit at the cost of increased porosity. Additionally, the styrofoam pattern thickness was found to affect the dimensional stability and surface roughness of the composites, with thicker patterns resulting in higher surface roughness. This study highlights the potential of utilizing rice husk ash as a reinforcing material in aluminium matrix composites, offering a sustainable approach to improving material properties. The findings suggest that an optimal balance of composition ratio, pouring temperature, and pattern thickness is crucial to achieving desirable mechanical and physical characteristics, with implications for advanced manufacturing processes in the materials industry.
Optimization of bio-based cellulose-phosphate hydrogel production from rice husk waste using the Taguchi method Selvia Aprilyanti; Irnanda Pratiwi; Winny Andalia; Tine Aprianti; Hariman Al Faritzie
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.47172

Abstract

This work reports the development and statistical optimization of a fully Bio-based absorbent hydrogel synthesized from rice husk–derived cellulose via phosphoric acid crosslinking. Cellulose was extracted through sequential chemical treatments and subsequently converted into a phosphate-crosslinked hydrogel using a controlled synthesis process. A Taguchi L16 (4⁵) orthogonal array was employed to optimize four key synthesis parameters: cellulose content, reaction time, heating temperature, and phosphoric acid volume. Hydrogel structure and morphology were characterized using Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). FTIR results confirmed the formation of phosphate ester linkages, indicating successful crosslinking, while SEM observations revealed a porous and interconnected network structure favorable for water absorption. The optimized hydrogel formulation achieved a maximum swelling ratio of 91.25 g/g, demonstrating effective absorbent performance despite the absence of synthetic monomers or grafting agents. These findings indicate that rice husk waste can be efficiently valorized into an environmentally benign absorbent material through a simple and statistically guided synthesis route, supporting sustainable hydrogel development and agricultural waste utilization.
Spatial modelling of shallow groundwater quality in coastal areas with Kriging interpolation Yaumal Arbi; Nurhasan Syah; Iswandi Umar; Indang Dewata; Mulya Gusman; Nevy Sandra
Teknomekanik Vol. 9 No. 1 (2026): Regular Issue
Publisher : Universitas Negeri Padang

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.24036/teknomekanik.v9i1.47272

Abstract

This study maps shallow coastal groundwater quality in Padang, Indonesia, using four operational parameters: potential of hydrogen (pH), electrical conductivity (EC), total dissolved solids (TDS), and salinity. We characterize spatial dependence using empirical variograms, evaluate directional anisotropy, and generate prediction surfaces with Ordinary Kriging. The variogram analysis indicates stronger spatial continuity along the coastline for EC and TDS, while salinity shows shorter continuity with a distinct directional structure, reflecting localized freshwater-seawater mixing processes. Groundwater pH remains neutral to slightly alkaline and exhibits lower spatial variability than EC, TDS, and salinity. Leave-one-out cross-validation supports the reliability of the kriging estimates at the study scale, indicating low prediction error and strong agreement between observed and predicted values. The resulting thematic maps enable a three-level quality zoning that differentiates a lower-risk northern segment, a transitional central belt, and a higher-risk southern segment consistent with seawater intrusion influence. These outputs provide a practical basis for prioritizing monitoring locations, protecting vulnerable wells, and strengthening evidence-based coastal groundwater management aligned with SDG 6 Clean Water and Sanitation and SDG 11 Sustainable Cities and Communities.

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