AbstrakTujuan dari penelitian ini adalah menentukan spesimen uji agar bisa diterima berdasarkan acceptance criteria ASME. Penelitian ini menggunakan material mild steel dengan nilai kekerasan 135 HVN dengan ukuran 30 cm x 20 cm x 1,2 cm yang disambungkan dengan proses pengelasan SMAW posisi 3G buttjoint dengan elektroda rooting LB 52U diameter 2.6 mm menggunakan arus 70 Amper dan tegangan 380 volt, sedangkan untuk filler menggunakan elektroda LB 5218 diameter 3,2 mm dengan arus 80 Amper dan tegangan 380 volt. Pada proses pengelasan banyak hal terjadi yang dipengaruhi oleh banyak faktor baik yang sengaja maupun yang tidak disengaja. Metode untuk menginspeksi hasil lasan salah satunya dengan uji tidak merusak metode dye penetrant (NDT-PT) yang hasilnya akan ditentukan berdasarkan acceptance criteria berdasarkan standar ASME. Hasil pengujian menunjukkan adanya discontinuity berupa adanya porositas pada permukaan hasil pengelasan pada spesimen 1 terdapat rounded terbesar 5 mm pada jarak 233 mm sehingga berdasarkan acceptance criteria standar AWS dinyatakan hasil pengelasan tersebut accepted dan pada spesimen 2 terdapat discontinuity pada jarak 233 mm dengan ukuran 8 mm sehingga dinyatakan rejected. Hasil rejected ini dapat diperbaiki dengan cara di gouging pada discontinuity tersebut kemudian dilakukan pengelasan. Kata Kunci: NDT-PT, SMAW, Butt Joint, ASME AbstractThe purpose of the research are determine acceptance criteria the specimen based on ASME standard.
AbstrakMenipisnya cadangan bahan bakar fosil dan gas alam membuat manusia berfikir ulang untuk mencari pengganti energi aletrnatif. Biomassa merupakan energi alternatif yang masih melimpah dan belum termanfaatkan secara maksimal. Gasifikasi merupakan salah satu alternatif dalam pembuatan gas yaitu mengubah dari bahan bakar padat (serbuk kayu) menjadi gas yang mudah terbakar secara termokimia. Penelitian menggunakan gasifikasi tipe downdraft dengan bahan serbuk kayu secara eksperimental. Pelaksanaan penelitan dilakukan diworkshop kampus Polindra, menggunakan sistem batch, artinya 1 kali pemasukan biomassa pada tungku dari awal sampai biomassa habis sebesar 5 kg biomassa serbuk kayu. Equivalence Ratio (ER) dilakukan 4 variasi yaitu: 1,01; 1,13; 1,34; 1,52. Data-data yang dicatat berupa: temperatur di dalam reaktor, waktu operasi gasifikasi, debit udara masuk, kandungan syngas, dan visualisasi nyala api.
Portable vacuum grain conveyor (PVGC) work as transporting grain materials such as grain, wheat, sorghum, corn and its kind using air media. The advantages of this machine are that it can move material quickly, the material does not fall in the transportation process, it can move from the bottom to the top or vice versa, it does not require a feed hopper, and the machine can move places. How the PVGC machine works by utilizing the suction and thrust of a vacuum blower. The seed material is sucked in by the input hose and then into the cyclone to separate the air and seed material. Air from the cyclone enters the vacuum blower through the input hole and is blown into the output line to push the material falling from the cyclone through the rotary airlock. Seed material out through the output hose is directed to the desired place. Performance testing of the PVGC engine includes noise, the air suction speed of the input hose and the thrust speed of the output hose, the engine capacity, and thermal testing. The highest noise test results in the electric vacuum blower motor was 95.5 dBA ±1, the air suction speed at the input hose was 38 m/s ±3, the air thrust speed at the output hose was 44 m/s ±2, the capacity of the PVGC machine could transport IR64 of grain type with weighing 88 kg/minute. The hottest component was in the vacuum blower with a temperature of 52.50C.
Crashworthiness is the ability to protect its occupant by absorbing the energy of impact during a collision. A crush initiator is one way to increase crashworthiness criteria at collision. The most widely applied crush initiator applications are holes, wall thickness reduction, grooves, notch, bead and corrugated. This study discussed making a functional model from the crashworthiness criteria which is known by CFE and SEA. Variable used variations of the crush initiator in the form of circular holes with different rotation angles and diameters. The rotation angle referred to in this study was 2 holes which are rotated based on the midpoint of the hole distance to the radial axis of the hole. The crush initiator was placed in a square column at each side with steel material. Besides, the wall thickness variable was added which can increase the energy absorption during a collision. The method used numerical simulation and experimental dynamic loading. The numerical simulation used the explicit finite element method by using ESI PAM-Crash. Both methods used the drop test model by using impact transferability. Impact transferability was rigid which was used to transfer impact loading during impact conditions. Experimental was used to validate the function model which was obtained through the least square method with sampling from numerical simulations. The results showed the same patterns produced by the functional and experimental models using the Taguchi method (L9) with 3 runs. The maximum of this pattern is 23% for CFE and 17% for SEA. Meanwhile, the average error of the S/N ratio shows 8.77% for CFE and 2.16% for SEA. This model function could be used by a crashworthy designer to estimate the value of CFE and SEA.
Collision test is needed in transportation area in order to anticipate injuries of passangers when the accident occurred. Therefore, this test must be done for achieving standar requirements which is known by crashworthiness. This paper discussed about development of crasworthiness test by using modelling impact transferability by numerical simulation. The goal is to know the error of maximum deformation when given axial dynamic loading between numerical simulation and real experiment. Furthermore, analitic was used to validate duration of stress wave propagation from result of numerical simulation. This simulation used explicit finite element method by using PAM-Crash. The component of this research was impactor and impact of transferability with 80 and 27 kg of mass. The square tube-thin walled structure with holes as crush initator 3 mm of diameter was used as specimen. The result shows maximum deformation and duration of stress propagation error which are 3.90 % and 14.89 %.
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