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Rotasi
Published by Universitas Diponegoro
ISSN : 1411027x     EISSN : 24069620     DOI : -
Core Subject : Engineering,
Mechanical Engineering
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Articles 676 Documents
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Back Matter ROTASI Volume 23 Nomor 2 April 2021 Rotasi, Rotasi
ROTASI Vol 23, No 2 (2021): VOLUME 23, NOMOR 2, APRIL 2021
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.23.2.App. 1-4

Abstract

Penentuan Sudut Kemiringan Kristis Struktur Dinding Silo Berkapasitas Penyimpanan 4650 Ton Widyanto, Susilo
ROTASI Vol 22, No 3 (2020): VOLUME 22, NOMOR 3, JULI 2020
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.22.3.%p

Abstract

Konstruksi dinding silo dirancang untuk menerima beban desak dalam arah radial. Namun akibat kondisi tertentu, orientasi konstruksi silo dapat mengalami ketidak-tegak-lurusan terhadap bidang horisontalnya. Pada kondisi seperti ini, dinding silo mengalami beban gabungan yang berupa berupa beban desak dalam arah radial dan beban gravitasi.  Paper ini membahas penentuan sudut kemiringan kritis konstruksi dinding silo yang dikaitkan dengan distribusi tegangan yang terjadi. Investigasi dilakukan dengan simulasi FEM untuk konstruksi silo dengan kapasitas penyimpanan sebesar 4650 ton, diamater 19 m dengan ketinggian 20,875 m. Hasil simulasi FEM menunjukkan bahwa pada sudut kemiringan 5o, tegangan maksimum yang terjadi sebesar 24,4 kg/mm2, dimana besar tegangan tersebut hampir mendekati tegangan yield material yaitu 25 kg/mm2. Tegangan maksimum terjadi pada daerah sambungan antara dinding dan stifner
The Effect of The Ratio of Blood Shells (Andara Granosa) and Natural Fibers to The Bending Strength of The Composite Utami, Arum Vania
ROTASI Vol 23, No 1 (2021): VOLUME 23, NOMOR 1, JANUARI 2021
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.23.1.1-5

Abstract

Particle board composites that uses fiber as alternative to meet the needs of wood which is significant increase while forest resources can not meet it. The manufacture of fiber boards experienced instability in several quarters of 2015, in the first quarter 82,30 thousand m3 of fiber boards were produced and continued to experience a significant increase per year. In addition, increasing amount of waste palm fiber and coconut fiber also causes problems for the environment. This research aims to determine the effect of ratio of blood shells (Anadara granosa) and natural fibers to the bending strength of the composite. In this research used hand lay up method or manual printing by pressing the mold according to free variable i.e. fiber type with volume fraction 0:30, 20:10, 15:15, and 10:20 (%v). Obtained a composite with coconut fiber has the greatest average bending strength when the volume fraction ratio of blood shells and coconut fiber 0:30 is equal to 39,57 MPa, while the composite with palm fiber has the greatest average bending strength when the fraction ratio 10:20 volume of 39,57 MPa.
Pemodelan dan Optimasi Multiobjektif Refrigerator Kompresi Uap Menggunakan Metode Meminimalkan Pembangkitan Entropi Dwinanto, Matheus
ROTASI Vol 23, No 2 (2021): VOLUME 23, NOMOR 2, APRIL 2021
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.23.2.36-42

Abstract

The vapor compression refrigerators have many applications for cooling and freezing. The advantage of this system has good performance, and can meet the needs of a relatively large cooling capacity with a small system size. But behind its advantages, the energy consumption of this system is high so that energy saving is the main goal of optimization and this will continue to be done in a sustainable manner in the future. In this article, thermodynamic design optimization is presented to minimization entropy generation, minimization total power input, maximization the efficiency of the second law, and maximization the performance coefficient, simultaneously. A multi-objective genetic algorithm is used during the optimization process, and based on the Pareto frontier a decision-making strategy is obtained and then used to determine the final solution. The optimization results show that the method of minimization entropy generation can experience a paradox, where minimizing the entropy generation number of the system will not automatically result in the maximum efficiency of the second law but there is an optimal point which indicates that the generation of entropy is minimum. From the results of thermodynamic design optimization of the refrigerator, the total input power is 0.281 kW, the second law efficiency is 0.311 and coefficient of performance is 2.95.
Electricity Production from Food Waste Leachate (Fruit and Vegetable Waste) using Double Chamber Microbial Fuel Cell: Comparison between Non-aerated and Aerated Configuration Prasidha, Willie
ROTASI Vol 22, No 3 (2020): VOLUME 22, NOMOR 3, JULI 2020
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.22.3.162-168

Abstract

Two double chamber microbial fuel cells with different configurations were developed to produce electricity food waste leachate and studied for 30 days. Anode and Cathode were made by uncoated carbon felt and graphite rods.  Food waste and water were incubated into the reactor. After more than 30 days, leachate with the neutral condition (pH 6.9) was collected from the leachate reactor. 500 ml leachate was used in the anode chamber and 500 ml catholyte was used in the cathode chamber. The first configuration, non-aerated MFC, the maximum OCV, maximum power density, average power density, and maximum current density were 373 mV, 25.7 mW/m2, 3.7 mW/m2, and 21.4 mA/m2 respectively. For the second configuration, aerated MFC, maximum OCV, maximum power density, average power density, and current density were 404 mV, 25.7 mW/m2, 6.1 mW/m2, and 21.4 mA/m2 respectively. Aerated MFC had higher maximum OCV and average power density than non-aerated MFC. From the study, supplying continuous dissolved air (oxygen) in the cathode chamber can produce more voltage and average power density in double chamber microbial fuel cell.
Analisis Desain Cetakan Straight Parallel Bipolar Plate pada Proses Pembentukan Superplastis dengan Metode Simulasi Numerik Choirotin, Ismi
ROTASI Vol 22, No 4 (2020): VOLUME 22, NOMOR 4, OKTOBER 2020
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.22.4.260-265

Abstract

Abstract As the most important component of fuel cell, bipolar plate has developed by many researcher to get it best performance. Some considerations have been made including the type of material, the forming process and the geometric design to obtain bipolar plates which produce efficient renewable energy. The objective of this study was to obtain the best bipolar plate geometry in straight parallel microchannel types by varying the corner radius value.The superplastic forming process was analyzed by numerical simulation method using ANSYS software. The investigation exhibit that the microflow channel of bipolar plate with maximum depth of 6.64 mm was produced by 2.0 mm corner radius. An increased corner radius will rise the thickness reduction percentage, however an even thickness distribution was resulted. Kata kunci:  Abstrak  Memegang peranan penting sebagai bagian dari fuel cell, penelitian tentang bipolar plate banyak dikembangkan untuk mendapatkan performa terbaik. Banyak pertimbangan dalam pembuatan bipolar plate yang menentukan performa fuel cell dalam menghasilkan energi, diantaranya jenis material, proses pembentukan dan desain geometrinya. Tujuan dari penelitian ini adalah untuk mendapatkan geometri bipolar plate terbaik pada tipe saluran straight parallel dengan memvariasikan nilai corner radius. Metode yang digunakan ada penelitian ini adalah simulasi numerik pada proses pembentukan superplastis dengan menggunakan software ANSYS. Dari hasil analisis yang telah dilakukan, didapatkan saluran bipolar plate  dengan kedalaman maksimal sebesar 6,64 mm pada variasi corner radius cetakan terbesar yaitu 2,0 mm. Peningkatan harga corner radius akan meningkatkan prosentase pengurangan ketebalan material akan tetapi ketebalan yang dihasilkan juga lebih merata jika dibandingkan harga corner radius yang lebih rendah. Kata kunci: 
Back Matter ROTASI Volume 23 Nomor 1 Junuari 2021 Rotasi, Rotasi
ROTASI Vol 23, No 1 (2021): VOLUME 23, NOMOR 1, JANUARI 2021
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.23.1.App 1-4

Abstract

Pengaruh Ukuran Partikel dan Feed Rate Pasir pada Sistem Sanding Kereta Api terhadap Kecepatan Putaran dan Kekasaran Permukaan Roda dan Rel Paryanto, Paryanto
ROTASI Vol 22, No 4 (2020): VOLUME 22, NOMOR 4, OKTOBER 2020
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.22.4.229-235

Abstract

Sanding is a method where a certain amount of sand is sprayed between the wheels and rails during emergency braking or other operations that require high coefficient of friction. However, an inappropriate sanding method can accelerate the wear and damage the surface of the wheels and rail. Therefore, this study aims to determine the most efficient parameters of the sand size and its feed rate for increasing the friction coefficient between the wheels and rails. The experimental is conducted using ST 60 steel for the wheel and ST 90 steel as rail test specimen. The experiments are done by rotating the wheel specimen on the rail specimen with a constant speed at 400 rpm. After that, water is dropped to the surface of the wheels and rails specimens at the flow rate 2 ml/min to create a wet surface condition. In the experiments set up, there are three sand variations of grain size, i.e. mesh 80-200, mesh 30-50, and mesh 20-30 with sanding rate 5 gram/min, 7 gram/min, and 10 gram/min. Based on the experimental results, it was found that the larger the sand grain size and feed rate, the slip ratio between the wheel and rail will decrease but the surface roughness of the wheel and rail will also increase. The optimal sand size for reducing the slip ratio between wheels and rails is 20-30 mesh sand (with 0.595-0.841 mm grain size) and at 10 gram/min feed rate. At this condition, the slip ratio between the wheel and rail is reduced to 1.05% with surface roughness value (Ra) of wheel 4.84 μm and 3.87 μm for rail specimen.
Pengaruh Penambahan Zat Aditif Pada Pengecoran Beton Joint Pit SKTT 150 kV Sario – Teling Fitrianto, Andrian Juli; Hakam, Dzikri Firmansyah; Prahastono, Iswan; Nainggolan, Akiman
ROTASI Vol 23, No 1 (2021): VOLUME 23, NOMOR 1, JANUARI 2021
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.23.1.39-49

Abstract

The construction of a 150 kV Sario - Teling High Voltage Cable Line (SKTT), which located in the city of Manado - North Sulawesi Province, is an important electricity project that has been planned to operate in 2020 according to the 2019-2028 Rencana Umum Penyediaan Tenaga Listrik (RUPTL). This transmission line construction is expected to increase electrical energy services in North Sulawesi region. This SKTT project applied the Boring Horizontal Directional Drilling (HDD) method to install the 150 kV SKTT cable. On the other hand, the Joint Pit installation uses a Box Culvert precast construction consisting of reinforced concrete.From the test results of the samples, we can conclude that there were an increases in the compressive strength of concrete from 1,04% to 1,27% above the compressive strength of normal concrete. There was a decrease in the compressive strength of the concrete at several points. However, this anomaly is still above the minimum limit of concrete compressive strength determined by PLN, which is 400 kg / cm2.This study involved laboratory testing to determine the effect of additives added during Box Culvert casting in order to obtain an efficient hardening time. It is hoped that this study will have an impact on the completion of the SKTT 150 kV Sario - Teling project on time, so that it can provide economic benefits for PLN and the consumer.
Front Matter Rotasi Vol. 23 No. 2 April 2021 Rotasi, Rotasi
ROTASI Vol 23, No 2 (2021): VOLUME 23, NOMOR 2, APRIL 2021
Publisher : Departemen Teknik Mesin, Fakultas Teknik, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/rotasi.23.2.i-v

Abstract

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