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INDONESIA
Rotasi
Published by Universitas Diponegoro
ISSN : 1411027x     EISSN : 24069620     DOI : -
Core Subject : Engineering,
Mechanical Engineering
Arjuna Subject : -
Articles 12 Documents
 1   2 
Search results for , issue "Vol 22, No 3 (2020): VOLUME 22, NOMOR 3, JULI 2020" : 12 Documents clear
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
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 PEMBEBANAN KAKI TIRUAN MONOCENTRIC PRODUK UNDIP ATAS LUTUT MENGGUNAKAN GROUND REACTION FORCE Ismail, Rifky
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.22.3.208-214

Abstract

Salah satu anggota gerak tubuh yang berperan penting untuk mobilitas adalah kaki. Akan tetapi, beberapa penyandang disabilitas terutama kehilangan kaki memiliki keterbatasan fisik yang menyebabkan mobilitas berkurang. Oleh karena itu, perkembangan kaki tiruan sangat membantu penyandang disabilitas dalam melakukan aktivitas sehari-hari. Salah satu produk kaki tiruan atas lutut yang telah dikembangkan oleh Universitas Diponegoro yaitu kaki tiruan atas lutut dengan sendi mekanik. Akan tetapi dalam proses analisis pembebanan, hanya menggunakan pembebanan 100kg. Sehingga dalam penelitian ini, dilakukan analisis pembebanan menggunakan ground reaction force. Hasil analisis pembebanan ground reaction force pada gait cycle 17% menghasilkan tegangan von Mises maksimal sebesar 18,47 MPa, deformasi maksimal sebesar 0,11 mm dan safety factor sebesar 14,94. Sedangkan pada gait cycle 47% menghasilkan tegangan von Mises maksimal sebesar 20,88 MPa, deformasi maksimal sebesar 0,14 mm dan safety factor sebesar 13,21. Hal ini dapat disimpulkan bahwa kaki tiruan atas lutut tersebut dapat menerima beban terbesar pada gait cycle 47% yang lebih besar daripada gait cycle 17%.
Analisis Roll Bending Process Pada Square Pipe Dengan Desain Flexible Roll sufiyanto, sufiyanto; Andrijono, Djoko
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.22.3.169-179

Abstract

The roll bending process is used to form the curved frame needed for making canopies and iron fences. The number of stages of the roll bending process is determined by the frame's curvature radius, thickness, cross-section size and the pipe material used. The flexible roll design aims to ensure that the dies roll can be used for the roll bending process with various of square pipe sections. It is necessary to analyze the roll bending process of square pipe to make the curved frame with a flexible roll design. This analysis aims to calculate the required bending force and the bending stress that occurs. The method used in this analysis uses two ways. First, the bending force is determined based on the strength of the pipe material used. Second, the bending force is determined based on the amount of lateral deflection given. The results obtained from the analysis of the first method are the bending force required of 488.4 kg on a square pipe with  2.2 mm thickness and  3 cm x 3 cm pipe size; 868.3 kg at 4 cm x 4 cm pipe size; 1953.6 kg at 6 cm x 6 cm pipe size. The conclusion of the first method is that the forming process occurs when the bending force applied must be able to produce plastic deformation in the formed pipe. Whereas the second method produces a limitation that the lateral deflection that occurs should not exceed the limit of the permissible bending stress in order to avoid buckling.
Front Matter Rotasi Vol. 22 No. 3 Juli 2020 Rotasi, Rotasi
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.i-v

Abstract

Front Matter
Terbentuknya White Layer pada Proses Milling Austempered Ductile Iron (ADI) Rusnaldy, Rusnaldy; Umardani, Yusuf
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.22.3.180-187

Abstract

Machining processes cause a white layer at the surface of a work piece. A white layer is a featureless layer that typically forms on machined steel surfaces and appears white when observed under an optical microscope after standard metallographic preparation. A white layer is known to be a function of the cutting conditions and its thickness ranges from a few microns to a few tens of microns. A white layer is generally a hard phase and leads to the surface becoming brittle causing crack permeation and product failure. This layer has been reported in a wide range of materials, from mild steels to nickel-based super alloys. This paper reports on an investigation of white layer formation for a range of cutting speeds, feeds and depth of cut  in milling of Austempered Ductile Iron (ADI). To produce ADI, ductile irons  were first austenitized in furnace at 900oC for 1 hour and then they were quenched in salt bath at 375oC for 1 hour.  The machined specimens were analysed using a optical microscope with software Lumenera Infinity 1 to measure the thickness of white layer dan a micro hardness tester. The present results reveal that white layers were formed on the machined surfaces of ADI. The machined surface showed an increase in hardness with respect to the bulk material. The effects of cutting speeds, feeds and depth of cut on thickness and micro hardness of  white layers are reported in this paper.
Analisis Pengaruh Perubahan Ukuran Cam Lobe Lift terhadap Performa pada Mesin Otto Empat Langkah Kurniawan, Nicholas; Soewono, Arka; Iskandar, Isdaryanto
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.22.3.143-148

Abstract

The modification of cam lobe lift value was studied to observe its effects on the volumetric efficiency and performance of a 4-stroke Otto engine with a displacement of 150 cc. The testing was done by comparing the standard cam lobe with 7,36 mm lift and two other cam lobes with a higher lift, which is 8,24 mm and 8,53 mm. ANSYS software was used as a method to acquires the volumetric efficiency value, while a dynamometer was used to measures the performance. From the calculation and testing that has been done, the usage of both modification cam lobes increase the volumetric efficiency and performance of the engine. Compared with the standard cam, the cam with 8,53 mm lift result in an increase of volumetric efficiency from 78,51% to 84,1% and performance from 15,36 WHP to 15,76 WHP at 9000 rpm.
Back Matter ROTASI Volume 22 Nomor 3 Juli 2020 Rotasi, Rotasi
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.App. 1-4

Abstract

The relationship between heel pad compressibility index, age, body mass index and foot area contact in calcanea spur patients Wibowo, Dwi Basuki; Suprihanto, Agus; Haryadi, Gunawan Dwi
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.22.3.188-193

Abstract

This study was performed to investigate the relationship between heel pad compressibility index (HPCI), age, body mass index (BMI) and (FAC) for calcanea/heel spur patients. Thirteen patients with a symptomatic heel spur (3 males and 10 females) participated in this study. The HPCI increased with age and HPCI of the elderly is greater than the adult. The HPCI increased with pain minimum compressive pressure (PMCP) indicated HPCI are all significantly greater in patients with plantar heel pain than in normal subjects. The BMI increased with FAC is caused by BMI and FAC of males is greater than females. The PMCP decreased with BMI indicated that patient with excessive body mass will make experience more pain. The result of pain measurement showed that there are 7 patients who indicated the abnormality (the PMCP value is lower than 2 kg/cm2). From this study, it can be concluded that the quantitatively pain level is worst when PMCP< 2.0 kg/cm2, it is severe when 3.0> PMCP ≥ 2.0 kg/cm2 and it is moderate when PMCP≥3.0 kg/cm2
The effect of expander input and output pressure ratio on the performance of simple organic Rankine cycle with low quality geothermal steam as the heat source Siregar, Achmad Husein
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

Electricity currently plays essential role to support the lives of modern society and national development in Indonesia. The use of renewable energy resources to produce electricity need to be continually encouraged since the exploitation of fossil energy sources to generate power have been depleting the energy reserves. In addition, the use of fossil energy pollutes for the environment. For these reasons, a lot of studies need to be carried out to find out the best possibilities to generate power using renewable energy sources.In this study an experimental investigation of the performance of a small-scale power generation system using an organic Rankine Cycle (ORC) system with a low-quality geothermal steam as the heat source is carried out. The experimental system was designed, built and tested using R134a as a working fluid. This small-scale power generation unit uses key components such as a vane type pump, to increase the pressure of the working fluid, the evaporator, to absorb heat from the heat source, the expander (turbine), to expand the heat vapour to generate work on shaft, and the condenser, to change the fluid phase into saturated liquid. Some parameters such as heating steam temperature and mass flow rate of the working fluid will be varied during the experiment to obtain the best system performance. From the test results it is obtained that the highest thermal efficiency of the system is 5.34% and the net output power is 1523.42 Watt. The experimental results show that using low-quality geothermal steam in the power generation system using this ORC system is feasible to use with acceptable performance. Keywords: renewable energy, geothermal, organic Rankine cycle

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