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Jamasri .
Fakultas Teknik, Universitas Gadjah Mada, Yogyakarta
Aerospace Engineering Agriculture, Biological Sciences & Forestry Humanities Automotive Engineering Chemical Engineering, Chemistry & Bioengineering Chemistry Civil Engineering, Building, Construction & Architecture Computer Science & IT Control & Systems Engineering Decision Sciences, Operations Research & Management Earth & Planetary Sciences Education Electrical & Electronics Engineering Energy Engineering Environmental Science Industrial & Manufacturing Engineering Materials Science & Nanotechnology Mechanical Engineering Physics Social Sciences

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STUDI PERLAKUANALKALI DAN TEBALCORE TERHADAPSIFAT BENDING KOMPOSIT SANDWICH BERPENGUAT SERAT SAWIT DENGAN CORE KAYU SAWIT Jamasri Jamasri; Kuncoro Diharjo; Gunesti Wahyu Handiko
Jurnal Sains Materi Indonesia Vol 8, No 1: OKTOBER 2006
Publisher : Center for Science & Technology of Advanced Materials - National Nuclear Energy Agency

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (763.948 KB) | DOI: 10.17146/jusami.2006.8.1.4825

Abstract

STUDI PERLAKUANALKALI DAN TEBALCORE TERHADAPSIFAT BENDING KOMPOSIT SANDWICH BERPENGUAT SERAT SAWIT DENGAN CORE KAYU SAWIT. Kebijakan pemerintah tentang perluasan lahan sawit mendorong para peneliti untuk saling mengembangkan penggunaan berbagai produk sawit. Saat ini, pemerintah akan melakukan peremajaan tanaman sawit seluas 500.000 Ha. Kajian riset yang memanfaatkan aneka produk sawit dipandang penting untuk segera dilaksanakan. Penelitian ini bertujuan untuk menyelidiki pengaruh perlakuan alkali dan tebal core terhadap sifat bending komposit sandwich berpenguat serat sawit dengan core kayu sawit. Bahan penelitian adalah limbah serat sawit, kayu sawit, dan unsaturated polyester resin (UPRs). Serat sawit yang digunakan sebagai penguat, dicuci dengan air dan dilanjutkan dengan pengeringan. Sebagian dikenai perlakuan alkali (5% NaOH) selama 2 jam. Kayu sawit yang digunakan dipotong pada arah melintang dengan variasi ketebalan 10 mm, 15 mm, 20 mm, dan 25 mm. Pembuatan komposit dilakukan dengan metode cetak tekan. Pengujian bending komposit skin (serat sawit-poliester) dilakukan dengan mengacu pada standar ASTM D-790 pada fraksi massa serat antara 10% sampai dengan 50%, sedangkan pengujian bending komposit sandwichnya dilakukan dengan mengacu pada standar ASTM C-393. Komposit skin dan sandwich yang diperkuat serat perlakuan alkali (5% NaOH) memiliki kekuatan yang lebih tinggi. Kekuatan bending komposit skin yang diperkuat serat tanpa perlakuan pada Wf = 18,2% dan Wf = 29,5% adalah 21,67 Mpa dan 24,02 Mpa. Selanjutnya, kekuatan bending komposit skin yang diperkuat serat perlakuan alkali pada Wf = 17.6% dan Wf = 34,9% adalah 26,93 Mpa dan 36,04 Mpa. Kemampuan menahan momen komposit sandwich meningkat seiring dengan peningkatan ketebalan core. Namun, penebalan core akan menurunkan kekuatan bending komposit sandwich. Kekuatan bending komposit sandwich yang diperkuat serat tanpa perlakuan dengan core 10 mm dan 25 mm adalah 20,05 Mpa dan 14,23 Mpa, sedangkan kekuatan bending komposit sandwich yang diperkuat serat perlakuan alkali pada ketebalan core 10 mm dan 25 mm adalah 22,33 Mpa dan 16,31 Mpa. Mekanisme kegagalan diindikasikan oleh lemahnya komposit skin yang tidak mampu menahan beban bending.
ANALISIS DISTRIBUSI KETEBALAN DAN KEKERASAN HASIL CORAN SENTRIFUGAL ALUMINIUM PADUAN (Al-Mg-Si) AKIBAT PERUBAHAN LAJU PUTARAN DAN KEMIRINGAN SUMBU CETAKAN Sugiarto Sugiarto; Tjuk Oerbandono; Jamasri Jamasri; M Waziz Wildan
Journal of Environmental Engineering and Sustainable Technology Vol 1, No 1 (2014)
Publisher : Lembaga Penelitian dan Pengabdian kepada Masyarakat Universitas Brawijaya

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (877.536 KB) | DOI: 10.21776/ub.jeest.2014.001.01.3

Abstract

Pengaruh gaya sentrifugal pada pengecoran sentrifugal adalah mampu menghasilkan coran yang lebih padat dan beberapa sifat yang unggul lainnya dibanding pengecoran konvensional. Tetapi  kelemahannya adalah distribusi ketebalan dan kepadatan coran cenderung tidak merata, segregasi dan struktur yang tidak homogen akibat laju pembekuan yang tidak seragam, permukaan bagian dalam yang kasar akibat udara yang terjebak dan sebagainya. Kekurangan ini mungkin dapat diatasi dengan mengatur beberapa parameter seperti laju putaran, sudut kemiringan cetakan, karakteristik material coran, temperatur cetakan atau dengan memberikan perlakuan terhadap logam cair selama pengecoran.Penelitian ini mencoba mengatur laju putaran dengan variasi 1050 rpm, 1400 rpm, 1950 rpm dan 2300 rpm. Dan kemiringan cetakan diatur dengan variasi sudut 15°, 30°, 45° dan 60°. Bahan penelitiannya adalah aluminium paduan (Al-Mg-Si) dengan berat tiap penuangan 900 gram, temperatur penuangan 900 ºC dan waktu penuangan 120 detik.Hasilnya adalah distribusi logam cair tidak merata pada putaran 1050 rpm untuk semua sudut dan 1400 rpm dengan sudut 45º dan 60º. Pada permukaan bagian dalam produk terdapat bagian yang kasar (terdapat cacat permukaan) di hampir semua variasi putaran dan sudut, kecuali pada putaran 1400 sudut 15º, 1950 rpm sudut 60º dan 2300 rpm sudut 45º dan 60º. Pada putaran 1950 rpm dan 2300 rpm, distribusi ketebalan relatif merata untuk semua variasi sudut, sedangkan distribusi ketebalan yang paling merata adalah pada putaran 1950 rpm dan 2300 rpm dengan sudut 45º. Secara umum kekerasan di daerah ujung/benda kerja lebih tinggi daripada pada daerah tengah. Pada putaran 2300 rpm  dihasilkan distribusi kekerasan yang merata dengan kekerasan rata-rata yang lebih tinggi dibanding yang dihasilkan pada putaran yang lebih rendah.
Pemanfaatan Limbah Abu Terbang Sebagai Penguat Aluminium Matrix Composite Subarmono Subarmono; Jamasri Jamasri; M.W. Wildan; Kusnanto Kusnanto
Jurnal Teknik Mesin Vol. 10 No. 2 (2008): OCTOBER 2008
Publisher : Institute of Research and Community Outreach - Petra Christian University

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Abstract

This research aims to utilize fly ash which is obtained from waste of combustion of coal in steam power plant as a reinforcement of aluminum matrix composite (AMC). The amounts of fly ash of 2.5%, 5%, 7.5% and 10% wt were added to fine aluminum powder (dimension of particles are smaller than 40 µm). Each composition was mixed using a rotary mixer for 3 hr. The mixture was uniaxially pressed and it was followed by isostatic compaction with a pressure of 100 MPa to produce green bodies. They was pressureless sintered in argon atmosphere at various temperatures of 500°C, 525°C, 550°C, 575°C and 600ºC. Bending strength, Vickers hardness, wear resistance, density of the AMC were tested, and the microstructures were observed using SEM. The results show that the mechanical properties increase with increasing the fly ash content up to 5% wt. The bending strength, hardness, porosity and wear rate are 74 MPa, 66 VHN, 4.5% and 0.04 mg/(MPa.m), respectively. Abstract in Bahasa Indonesia: Penelitian ini bertujuan untuk memanfaatkan abu terbang sebagai penguat komposit bermatrik aluminium (AMC). Abu terbang merupakan limbah pembakaran batu bara pada pembangkit listrik tenaga uap. Abu terbang sejumlah 2,5%; 5%; 7,5% dan 10% berat dicampur dengan serbuk aluminium (ukuran serbuk lebih kesil dari 40 µm). Setiap campuran diaduk menggunakan rotay mixer selama 3 jam. Campuran aluminum dan abu terbang dikompaksi secara uniaksial dilanjutkan kompaksi secara isostatik dengan tekanan 100 MPa dan diikuti sintering tanpa tekanan dengan lingkungan gas argon dan variasi temperatur 500°C, 525°C, 550°C, 575°C dan 600°C. Kekuatan bending, kekerasan Vickers, ketahanan aus dan densitas komposit diuji serta struktur mikro diamati menggunakan SEM. Hasil pengujian menunjukkan bahwa sifat mekanis meningkat seiring dengan peningkatan fraksi berat abu terbang sampai 5% berat, selebihnya terjadi penurunan. Kekuatam bending, kekerasan Vickers, porositas dan laju keausan berturut-turut 74 MPa, 66 VHN, 4,5% dan 0,04 mg/(MPa.m). Kata kunci: Aluminum Matrix Composite, abu terbang, kompaksi, isostatik.
INFLUENCE OF REMELTING ON ALUMINUM ALUMINUM RAIN Aris Budiyono; Jamasri Jamasri
Jurnal Penelitian Saintek Vol 15, No 2: Oktober 2010
Publisher : Institute of Research and Community Services, Universitas Negeri Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (5873.567 KB) | DOI: 10.21831/jps.v15i2.1753

Abstract

The purpose  of this research is to observe the effect of remelting  on fatigue  crack growth rates of the aluminum  alloys. The material  used in this research was selected  aluminum scraps.  The material  was melt and cast at temperature  of  745°C in the metal molding, then was made specimen  according  to ASTM  E. 647. The remelting  was done three times at the same  condition.  The fatigue  crack growth  rate  testing  was performed  in a room temperature  condition with a constant load amplitude and the load ratio was maintained to be 0,3.The experiment result show that remelting can increase fatigue  crack growth rates whichwas shown by increasing ofn  exponential  values (I" remelting  was 4,4285 MFa.mo,s, 2nd4,5562 MFa.mo,s, and 3rd  4,6078 MFa.mo,5)Key words: remelting, fatigue  crack growth rates, aluminum alloys
FRACTURE SURFACE PADA KOMPOSIT HIBRID BERBASIS FIBERGLASS DAN COIR AKIBAT PENGARUH MOISTURE CONTENT Mastariyanto Perdana; Jamasri Jamasri
Jurnal Momentum ISSN 1693-752X Vol 17, No 1 (2015): Volume 17 No 1 Tahun 2015
Publisher : ITP Press

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (552.614 KB)

Abstract

Salah satu material teknik yang sangat banyak digunakan dibidang keteknikan adalah komposit. Ini disebabkan komposit memiliki sifat ringan dan relatif kuat. Namun, komposit yang berbasis serat sintesis dikurangi penggunaannya untuk mendapatkan sifat ramah lingkungan sehingga penelitian ini menggunakan serat hibrid dengan fraksi volume yang terdiri dari 12% fiberglass dan 18% coir. Fraksi volume antara serat hibrid dan epoksi adalah 30:70. Penelitian ini bertujuan untuk mengetahui bentuk patahan (fracture surface) komposit sebagai akibat pengaruh dari moisture content. Komposit direndam dalam air dengan variasi perendaman 6, 12, 18, dan 24 jam untuk mengetahui pengaruh dari moisture content tersebut. Hasil pengujian menunjukkan bahwa sebagai akibat moisture content menyebabkan terjadinya pull-out pada serat coir dan fiberglass pada komposit hybrid. Moisture content menyebabkan menurunnya interfacial bonding antara serat coir dan matrik sehingga akan menyebabkan terjadinya penurunan kekuatan dari komposit.
Assessment of Nugget Size of Spot Weld using Neutron Radiography Triyono Triyono; Jamasri Jamasri; M.N. Ilman; R. Soekrisno; Sutiarso Sutiarso
Atom Indonesia Vol 37, No 2 (2011): August 2011
Publisher : PPIKSN-BATAN

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.17146/aij.2011.65

Abstract

Resistance spot welding (RSW) has been widely used for many years in the fabrication of car body structures, mainly due to the cost and time considerations. The weld quality as well as the nugget size is an issue in various manufacturing and processes due to the strong link between the weld quality and safety. It has led to the development of various destructive and non-destructive tests for spot welding such as peel testing, ultrasonic inspections, digital shearography, and infrared thermography. However, such methods cannot show spot weld nugget visually and the results are very operator’s skill dependent. The present work proposes a method to visualize the nugget size of spot welds using neutron radiography. Water, oil and various concentrations of gadolinium oxide-alcohol mixture were evaluated as a contrast media to obtain the best quality of radiography. Results show that mixture of 5 g gadolinium oxide (Gd2O3) in 25 ml alcohol produces the best contrast. It provides the possibility to visualize the shape and size of the nugget spot weld. Furthermore, it can discriminate between nugget and corona bond. The result of neutron radiography evaluation shows reasonable agreement with that of destructive test. Received: 13 October 2010; Revised: 25 August 2011; Accepted 26 August 2011
INFLUENCE OF SINTERING TEMPERATURE AND HOLDING TIME ON TENSILE STRENGTH AND SHRINKAGE OF PVC SPECIMEN ON INDIRECT PRESSURE-LESS SINTERING PROCESS S. A Widyanto; S Riyadi; A. E Tontowi; Jamasri Jamasri; H. S Rochardjo
Mesin Vol. 21 No. 1 (2006)
Publisher : Mesin

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Abstract

Sintering process has proven to be a manufacturing process that can produce a mechanical part with high geometric complexity. Development of alternative sintering process is continuously conducted to find the most inexpensive process. A solution process which is called indirect pressure-less sintering were proposed in this research. Generally this process of making a mechanical part is initiated with arranging powder by deposition machine, and continued by sintering process in conventional furnace. Optimal parameters that consist of sintering temperature and holding time in this process were optimized in this paper. PVC powder and sand casting (silica) were used as a material product and supporting powder respectively. The variations of sintering temperature are 100, 105, 110, 115 and 120°C, while the holding times are 2, 4, 6 and 8 hours. The optimal parameters were found by measuring tensile strength and shrinkage of specimen. The experiment results showed that dimensional stability of specimen can not be maintained for sintering temperature of 115°C with holding time longer than 2 hours. In sintering temperature higher than 120°C, PVC material directly starts to melt so that the volume of specimen increased. This was caused by binding of supporting powder. The strength of binding mechanism was measured when sintering temperature was higher than 107°C. In sintering temperature of 113°C with varying the holding time (2-8 hours) gave the longest variation of tensile strength.
The Effect of Clay Addition on the Mechanical Strength of Unsaturated Polyester Hybrid Composite Reinforced with Woven Agel Leaf Fiber/Glass Fiber Orisanto Darma Setiawan; Kusmono Kusmono; Jamasri Jamasri
Journal of Material Processing and Characterization Vol 1, No 2 (2020): Articles
Publisher : Departmen Teknik Mesin dan Industri, Fakultas Teknik, Universitas Gadjah Mada

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (450.027 KB) | DOI: 10.22146/jmpc.68280

Abstract

In the field of material technology, natural fiber materials are candidates for reinforcement in the production of lightweight, high-strength, environment-friendly, economical composites. Hybrid composites are comprised of a variety of reinforcement, fillers, and polymers. The objective of this research was to figure out the effect of clay addition on the mechanical properties of hybrid composites reinforced with woven agel leaf fiber/glass fiber. The materials used included woven agel leaf fiber, glass fiber, clay, Yukalac BQTN 157 type unsaturated polyester resin, and methyl-ethyl ketone peroxide catalyst. Firstly, the woven agel leaf fiber was given an alkaline treatment by submersion in a 4% NaOH solution for 1 hour, then rinsed with clean water and dried in the open air for 48 hours. The composite manufacture process employed 3 sheets of woven agel leaf fiber and 4 sheets of glass fiber sized 25 cm × 20 cm with unsaturated polyester matrix. The manufacture method used was the vacuum bagging method with a suction pressure of –70 cmHg. The mechanical tests carried out consisted of tensile test (based on the ASTM D638 standard), bending test (based on the ASTM D790 standard), and impact test (based on the ASTM D5942 standard). The results show that an addition of 1 wt% clay was able to increase the tensile strength, bending strength, and impact strength of the hybrid composite reinforced with woven agel leaf fiber/glass fiber by 7.26%, 30.85%, and 36.25%, respectively.
Development of Low Frequency Vibration Method of Direct-Write Deposition Relevant to Layer Manufacturing Application Widyanto, Susilo Adi; Tontowi, Alva Edy; Jamasri, Jamasri; Budi Rochardjo, Heru Santosa
Makara Journal of Technology Vol. 9, No. 2
Publisher : UI Scholars Hub

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Abstract

The research of deposition process is the first step in development process of multi materials selective laser sintering. The deposition process enables to settle multi materials powder in horizontal formation on one layer. In this research we use low frequency (70 - 200Hz) to vibrate a hopper nozzle in which powder is settled. The research method consists of two steps, the first step is to determine flow-ability parameters and the second is to join flow ability parameter with other parameters such that the line width can be controlled. The results show that the line width depends on uniformity of particle size, particle size, frequency of vibration, deposition gap, particle shape and feed-rate of hopper-nozzle.
Determination of Operation Condition and Product Dimension Accuracy Optimization of Filament Deposition Modelling on Layer Manufacturing Application Widyanto, Slamet A.; Tontowi, Alva Edy; Jamasri, Jamasri; Rochardjo, Heru Santoso Budi
Makara Journal of Technology Vol. 10, No. 2
Publisher : UI Scholars Hub

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Abstract

Layer manufacturing process has proven as a process that can produce a high complexity mechanical part. Now, Improvement of LM methods continuously conduct that is aimed to increase precessions and efficiency of these processes. Pressure filament deposition modelling is a form of layer manufacturing process that is designed to produce a plastic part with controlling its semisolid phase. In this research, the equipment of filament depositor is designed and tested to make the product filament deposition. With operation condition observation, the optimal temperature and pressure of deposition process was determined. These experiments used PVC as crystalline material and polypropylene as amorphous material. To optimize this process, the tensile strength and density test were conducted. The shape of tensile test specimens is based on ASTM 638 standard and made in 3 orientations deposition path, namely: in 0 degree, 45 degree and 90 degree from load force axis. To found the most accurate dimension, controlling the time delay, temperature of build part, feeding speed and variation deposition path was conducted. The results of experiments show that the filament deposition method can only be applied for amorphous material in which it has a semisolid phase. From the tensile strength test, the binding strength among filaments is 0.5 kg/mm2, 20% of the tensile strength of filament. And the density of a sample product, which used the filament diameter of 0.8 mm, is 0.7668 g/cm3. Accuracy of product dimension can be increased by: controlling time delay in location where the motion orientation of hopper filament is changed and controlling temperature of build part surface.
Co-Authors A. E Tontowi A. Puspawan Alva Edy Tontowi Alva Edy Tontowi Alva Tontowi Alva Tontowi, Alva Aris Budiyono Budi Rochardjo, Heru Santosa Dawal, Siti Zawiah Md. Dawal, Siti Zawiah Md. Duskiardi Duskiardi Gunesti Wahyu Handiko H. Hestiawan H. S Rochardjo Hendri Hestiawan Hendri Hestiawan Heru Santoso Budi Rochardjo Heru Santoso Budi Rochardjo, Heru Santoso Heru Santoso Budi Rochardjo, Heru Santoso Budi Iswanto, P.T. Iswanto, P.T. Khasanah, Rahayu Kuncoro Diharjo Kusmono Kusnanto Kusnanto Kusnanto Kusnanto M. Waziz Wildan M.N. Ilman M.N. Ilman, M.N. M.W. Wildan M.W. Wildan Mastariyanto Perdana Nur Subeki Orisanto Darma Setiawan R. Soekrisno Riyadi, S Rizky Arman Rochardjo, H. S S Riyadi S. A Widyanto Slamet Widyanto Slamet Widyanto, Slamet Subarmono Subarmono Subarmono Subarmono Sugiarto Sugiarto Suryadima Suryadima Susilo Adi Widyanto Susilo Widyanto Susilo Widyanto, Susilo Sutiarso Sutiarso Tjuk Oerbandono Tontowi, A. E Triyono Triyono Wenny Marthiana Widyanto, S. A Widyanto, Slamet A. Yovial Mahyoedin