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Mekanika: Majalah Ilmiah Mekanika
Published by Universitas Sebelas Maret
ISSN : 14127962     EISSN : 25793144     DOI : https://doi.org/10.20961/mekanika
Core Subject :
"Mekanika: Majalah Ilmiah Mekanika" is an open-access journal published by Mechanical Engineering Study Program, Faculty of Engineering, Universitas Sebelas Maret. Mekanika invites scholars, researchers and practioners who have interest in mechanical engineering to publish their articles and also provides forums for them to share their works and knowledge. Mekanika focuses on the area of materials engineering and science, design, energy, manufacturing and construction but is not limited to. Both English and Bahasa are accepted in this journal. Mekanika has two issues every year (March and September) and aims to publish more frequently in the future.
Arjuna Subject : Teknik (semua kategori) - Teknik Mesin
Articles 75 Documents
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Prospects and State of the Glass Industry in Saudi Arabia and a preliminary assessment of the quality of Glass and Glass-Ceramics Fabrication Mahmoud, Essam R. I.; Shaharoun, Awaluddin Mohamed; Aljabri, Abdulrahman; Almohamadi, Hamad; Farhan, Mohammed
Mekanika: Majalah Ilmiah Mekanika Vol 21, No 2 (2022): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v21i2.64294

Abstract

The current study presents a feasibility study of the fabrication of ordinary glass and glass ceramics from Saudi Arabian domestic raw materials. It discussed the glass industry in Saudi Arabia and the middle east region. It also gives a brief explanation of the sand geography in Saudi Arabia. Also, it represents experimental data about the fabrication of ordinary glass and glass ceramics from Saudi raw materials. Firstly, ordinary transparent glass without significant defects was fabricated with sand collected from the Ar-Rays region in Saudi Arabia. Four nanosized crystallization catalysts, namely Vanadium Carbide (VC), Tungsten Carbide (WC), Titanium Carbide (TiC), and Titanium Oxide (T2O3,) were added to the constituents of the Glass in 3% wt. For VC, the crystallization process was limited. The glass ceramics of WC consisted of multi-dimensional edges crystals that covered all of the matrices. The addition of TiC obtained gray crystalline whiskers. The Y2O3-glass ceramics consisted of multi-directionally rosette crystals. Finally, the microhardness values of the added crystallization catalysts in glass ceramics were much higher than in ordinary glass.
Experimental Test of Ignition Timing with Programable CDI on Performance Single Cylinder Otto Engine Rachmanto, Rendy Adhi; Wijayanto, Martinus Darmawan Bagas; Juwana, Wibawa Endra; Kataraki, Pramodkumar Siddappa
Mekanika: Majalah Ilmiah Mekanika Vol 21, No 2 (2022): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v21i2.58951

Abstract

Ignition timing is sparking from the spark plug based on the ignition angle during the compression stroke in the combustion chamber relative to the piston position and the crankshaft angular speed. Adjusting the ignition angle is one method to optimize the combustion process in the engine. An optimal combustion process can improve engine performance and reduce fuel consumption. This study investigates optimal data from ignition angle changes using a programmable Capacitive Discharge Ignition (CDI). The test was performed on a single-cylinder four-stroke Otto engine with standard ignition angle variations, +3°, +6°, and +9° before Top Dead Centre (TDC). The test results show that torque and power have increased while brake-specific fuel consumption has decreased. Optimal data acquisition at ignition angle of +9° with peak torque value of 6.91 Nm and peak power value of 4.80 kW, while the lowest value of specific fuel consumption is 0.234 kg/kWh, and the highest value of thermal efficiency is 36%. From this study, it was concluded that the ignition timing could affect the engine performance.
Experimental Study Influences Changes In Compression Ratio To Performance Of Single Cylinder Otto Engine Juwana, Wibawa Endra; Rachmanto, Rendy Adhi; Wiyono, Mugi; Istanto, Iwan
Mekanika: Majalah Ilmiah Mekanika Vol 21, No 2 (2022): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v21i2.59487

Abstract

Increasing the compression ratio is an attempt to increase the efficiency and performance of the engine. The purpose of the study was to analyze the effect of changes in the compression ratio on engine performance. Tests using a single-cylinder Otto engine by comparing the performance of an enlarged compression ratio of 9.7:1 and 10.4:1 with a standard compression ratio of 9.0:1. The result of the research is that the compression ratio of 9.7:1 produces a peak torque of 7.51 Nm at 6000 rpm, a peak power of 5.30 kW at 8000 rpm, and the lowest Brake-Specific Fuel Consumption (BSFC) is 0.146 kg/kWh at 6000 rpm. Torque and power increased by 0.09 Nm and 0.28 kW, and Brake-Specific Fuel Consumption (BSFC) decreased by 0.018 kg/kWh compared to the standard compression ratio of 9.0:1. Using a compression ratio of 10.4:1 produces a peak torque of 7.69 Nm at 6000 rpm, a peak power of 5.38 kW at 8000 rpm, and the lowest Brake-Specific Fuel Consumption (BSFC) is 0.116 kg/kWh at 6000 rpm. Torque and power increased by 0.27 Nm and 0.36 kW, and Brake-Specific Fuel Consumption (BSFC) decreased by 0.030 kg/kWh compared to the standard compression ratio of 9.0:1.
Failure Criteria in Crashworthiness Analysis of Ship Collision and Grounding Using FEA: Milestone and Development Carvalho, Hermes; Ridwan, Ridwan; Sudarno, Sudarno; Prabowo, Aditya Rio; Bae, Dong Myung; Huda, Nurul
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 1 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i1.70959

Abstract

This study presents reviews of the failure criteria to capture the resulting response due to the catastrophe of ship collision and grounding using the finite element. Researchers have introduced several failure criteria, for instance, the Det Norske Veritas (DNV) RP-C204 criterion, Germanischer Lloyd criterion, Peschmann, Rice-Tracey and Cockcroft-Latham (RTCL), Bressan-Williams-Hill (BWH) instability criterion, and Liu criterion. As in the mathematical formula, each criterion has a difference. The choice of failure criteria will depend on the simulation's specific requirements and the analysis's goals. Liu's criterion can be used to evaluate the failure of materials in ship collision simulations, for example, when large element sizes (i.e., 20 mm) are considered in the simulation.
Effect of Adding Al2O3 on the Macrostructure of Friction Stir Welding Polypropylene Sheet Clara, Dinda; Miksik, Frantisek; Kusharjanta, Bambang; Triyono, Triyono; Putri, Aniddya Salsabila Kurnia
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 1 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i1.63026

Abstract

In this study, an experimental investigation had been carried out to determine the effect of alumina (Al2O3) addition in joining Polypropylene. Polypropylene is a thermoplastic material used mostly as a non-metallic material. One of the joining methods that can be applied in Polypropylene is Friction Stir Welding (FSW). The use of Al2O3 as a filler was to modify the Polypropylene matrix's properties to improve the joint's quality. The Al2O3 powder with 99.9% purity was inserted along the Polypropylene plates in the groove. This research analyzed the role of adding Al2O3 and tool rotation speed concerning the joint's quality. The experiment was performed under different values of tool speed rotation (204 rpm, 356 rpm, 620 rpm, and 1140 rpm) and the presence or absence of the addition of alumina powder. Then, the joint's quality was visually observed by optical macroscopy at the top and cross-section view. From macroscopic observations, adding alumina could make the visual of the joint look better and result in minimum defects than the joint without alumina addition. Instead, the increasing tool speed rotation helped the distribution of alumina during the welding process.
Design Analysis and Structural Prediction of Bus Driver Chair Support: A Study Case using HOQ and FEM Cho, Joung Hyung; Ridwan, Ridwan; Kusuma, Rama Panji; Triyono, Joko; Muhayat, Nurul; Fajri, Aprianur; Laksono, Fajar Budi
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 1 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i1.44371

Abstract

The bus driver's comfort is crucial. The location of the driver's seat, which is correlated with the seat support design, is one of the elements supporting his comfort. By considering the safety factor, House of Quality (HOQ), weight, shape, and seat support dimensions, this study intends to ascertain how the characteristics of the bus seat support form after receiving a load or force. Conducting a field visit to gather the necessary data was the initial step in this research. The following stage was to decide on the design criteria based on the collected data. Next, use SolidWork to model the design. Using the Finite Element Method (FEM), this program can investigate design characteristics. The loading simulation under consideration included clutch engagement, bus brake application, and clutch engagement, whether the support was static or stationary. The validation with two supporting journals was then run as the following step to validate the findings. According to the study's findings, the constant chair support fulfills the typical value, whereas Support 1 was the most fracture-prone. The outcomes of Supports 2 and 3 demonstrated that the support strength was weak since it was subjected to an unequal load.
Mechanical Properties Of Pack Carburized AISI 4340 With Variation Energizer Composition of Barium Carbonate (BaCO3) And Sodium Carbonate (Na2CO3) Setiawan, Agris; Yusmania, Sapna; Sudiyanto, Anton
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 1 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i1.63870

Abstract

This research aimed to determine the mechanical strength of American Iron and Steel Institute (AISI) 4340 steel after pack carburizing with a combined variation of barium carbonate (BaCO3) and sodium carbonate (Na2CO3) as an energizer. Combination of two variations of energizer materials as an alternative to improve mechanical properties. The various ratios of energizer: 40/60, 50/50, and 60/40% w/w. The mechanical test was conducted to determine tensile (American Society for Testing and Material-ASTM E-8), impact strength (ASTM E-23), Rockwell hardness (ASTM E-18), and microstructure characterization (ASTM E-3). Both type specimens were temperature pack carburized was 950 ℃, and the holding time was 3 hours. Results showed that Specimen C had the lowest ultimate tensile strength mean value of the other specimens, which was 333.43±30.22 MPa. The impact test results showed that the lowest impact energy value was found in Specimen C, which is 4.32 Joules, and the highest impact energy value was found in specimens without treatment, which was 15.80 Joules. The microscope observation indicated that the specimen's microstructure was martensite structure increase, and the results of the hardness test were influenced by the martensite phase.
Effect of Screw Rotation Speed on Mechanical Properties and Morphology of Abs/Mcc Composites Adhana, Irvian; Smaradhana, Dharu Feby; Ariawan, Dody; Raharjo, Wijang Wisnu; Yusuf, Burhanuddin
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 1 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i1.70884

Abstract

Acrylonitrile Butadiene Styrene (ABS) polymer can be modified to increase strength against resistance, toughness, and heat resistance by adding Microcrystalline Cellulose (MCC) as a reinforcement to ABS composites. Extrusion is one of the established methods of polymer processing with filler and consequently disperses filler inside the polymer. Different speed shows different behaviour of filler dispersion. Therefore, this study was conducted to know the effect of extruder screw speed variations on the mechanical, physical, and thermal stability of ABS/MCC composites. The compositions used in producing ABS/MCC composites were 96% for ABS and 4% for MCC. The production process used screw extruder speed variations of 10 rpm, 15 rpm, and 20 rpm. ABS/MCC composite in the barrel and hot press used 160 °C for the temperature process. The highest tensile strength was obtained at 10 rpm variation for 14.2 MPa. Increasing the speed of the extruder screw caused a decrease in MCC content attached to ABS which reduced the mechanical strength. ABS/MCC composite density value decreased with the increased extruder speed, as evidenced by the increasing number of voids formed based on Scanning Electron Microscopy (SEM) testing.
Evaluating the Influence of Environmental Factors and Parameters on Advancements in Welding and Joining Processes: A Review Sudarno, Sudarno; Do, Quang Thang; Nubli, Haris; Prabowoputra, Dandun Mahesa; Agusti, Nur Candra Dana; Ridwan, Ridwan; Vandika, Anggi
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.75378

Abstract

This review article presents a comprehensive overview of welding, including its environmental influence, common welding failures, welding parameters, and predictions of development regarding welding and corrosion. The quality and integrity of welds can be significantly affected by environmental factors such as temperature, humidity, and atmospheric contaminants. Moreover, welding failures can occur due to various reasons, such as improper welding techniques, inadequate preparation, corrosion, or material defects, leading to structural weaknesses and compromised joint integrity. Furthermore, notable progress has been achieved in welding system technology, encompassing automation, robotics, and real-time monitoring. These advancements underscore the vital role of welding parameters in transforming control, precision, and productivity within the welding process. The integration of innovative welding systems has led to improved welding efficiency, reduced human error, and increased overall process reliability. This review consolidates knowledge from diverse sources, making it a valuable resource for researchers, practitioners, and industries involved in welding.
Repair Project Acceleration Strategy of Three Ship Units using Fuzzy Logic Analysis and Critical Path Method Ubyani, Hidayatus; Tuswan, Tuswan; Yudo, Hartono; Nubli, Haris; Mursid, Ocid; Iqbal, Muhammad
Mekanika: Majalah Ilmiah Mekanika Vol 22, No 2 (2023): MEKANIKA: Majalah Ilmiah Mekanika
Publisher : Universitas Sebelas Maret

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/mekanika.v22i2.76502

Abstract

This research uses the Critical Path Method (CPM) to analyze the main schedule of three combined ship repair projects. Then, shop-level planning is used to determine the productivity of each workshop so that each workshop knows the volume of work that needs to be completed daily. Furthermore, fuzzy logic is applied to analyze the risk of delays in repair project activities. The addition of working hours to critical work activities is accelerated from 30 days, the normal duration, to 23 days. Meanwhile, the addition of the workforce to critical work activities is accelerated from 30 days, the normal duration, to 22 days. The analysis of productivity values in each workshop results in the following productivity values: sandblasting and painting workshop 309.97 m2/person-days, piping workshop 4.12 units/person-days, fabrication workshop 407.16 kg/person-days, outfitting workshop 14.8 units/person-days, tank cleaning workshop 114.36 m3/person-days, and machining workshop 2.7 units/person-days. The fuzzy logic analysis results to determine the risk of delays in critical activities show that jobs with the codes SP1, SP2, SP3, SP4, M2, and SP5 have high risk of delay. Additionally, the collaboration with other departments in the company, such as the marketing, finance, and human resources departments, is ongoing to complete assigned tasks.

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