Studi Pengaruh Variasi Kuat Arus Pengelasan Pelat AISI 444 Menggunakan Elektroda AWS E316L

Baja tahan karat feritik sering digunakan dalam industri pengilangan minyak bumi. Pengelasan adalah proses manufaktur dan perawatan utama yang digunakan, salah satunya adalah pengelasan SMAW (Shielded Metal Arc Welding). Dalam studi ini, penulis menganalisa sifat mekanik pada sambungan pelat pengelasan baja tahan karat feritik AISI 444 dengan tebal pelat 2 mm dengan elektroda AWS A5.4 E316L diameter 2 mm. Karakterisasi yang dilakukan meliputi pengujian tarik, kekerasan mikro, dan struktur mikro. Berdasarkan data dari hasil penelitian didapatkan nilai kekuatan tarik spesimen raw material baja tahan karat feritik sebesar 555 N/mm2, sedangkan nilai kekuatan tarik spesimen hasil pengelasan arus 40 A sebesar 395 N/mm2, 60 A sebesar 511 N/mm2, dan 75 A sebesar 502 N/mm2. Terdapat cacat pengelasan berupa porositas pada weld metal pada pengelasan arus 40 A yang menyebabkan nilai kekuatan tarik menurun. Hasil uji kekerasan menunjukkan nilai tertinggi terdapat pada pengelasan arus 40 A yang memiliki rata – rata kekerasan pada daerah weld metal sebesar 353 HV, daerah HAZ sebesar 365 HV, dan weld metal sebesar 223 HV. Nilai kekerasan menurun seiring menurunnya arus pengelasan. Hal ini didukung dengan hasil uji struktur mikro, spesimen dengan arus pengelasan 40 A memiliki ukuran butir ferit lebih kecil di daerah HAZ, seiring bertambahnya arus pengelasan maka ukuran butir ferit poligonal semakin membesar yang menyebabkan kekerasan spesimen menurun. Kata kunci: Baja tahan karat feritik, SMAW, Uji tarik, Uji kekerasan mikro, Uji struktur mikro

Studi Upaya Penghematan Energi Listrik pada Gedung Asthabrata PT Mekar Armada Jaya

Audit energi merupakan kegiatan untuk mengidentifikasi jenis energi dan mengidentifikasikan besarnya energi yang digunakan pada bagian-bagian operasi suatu industri/pabrik atau bangunan serta mencoba mengidentifikasi kemungkinan penghematan energi. Audit energi yang dilakukan pada yaitu fokus pada penggunaan sistem pencahayaan dan sistem pendinginan. Gedung Asthabrata merupakan gedung di PT Mekar Armada Jaya yang berada di tengah-tengah kawasan autobody manufacturing PT Mekar Armada Jaya. Gedung yang digunakan sebagai kantorBidang Engineering. Dari data yang didapat konsumsi energi Gedung Asthabrata untuk sistem pencahayaan yaitu sebesar 50,8 kWh perhari, untuk sistem pendinginan sebesar 143,48 kWh perhari. Tingkat pencahayaan semua ruangan di gedung Asthabrata belum memenuhi standar yang ditetapkan oleh Badan Standar Nasional Indonesia. Kapasitas AC untuk semua ruangan di gedung Asthabrata belum memenuhi standar menurut perhitungan rumus yang ditetapkan. Hasil dari simulasi penghematan dapat disimpulkan bahwa dengan menggunakan lampu jenis LED dapat mengurangi jumlah energy sebesar 55% dari lampu jenis flourence. Untuk sistem pendinginan dilakukan simulasi penghematan dapat diketahui bahwa dengan menggunakan AC jenis inverter dapat mengurangi jumlah energy sekitar 56% dari AC jenis biasa. Dilihat dari simulasinya dapat ditarik kesimpulan bahwa simulasi ketiga dengan AC merek B paling signifikan dalam mengurangi jumlah penggunaan energy sebesar to73,1 kWh/hari. Kata Kunci: Audit energi, Sistem pencahayaan, Sistem pendingina

Analisis Kegagalan Baut Exhausted Lokomotif Mesin Diesel Elektrik Ditinjau dari Struktur Mikro Material dan Distribusi Tegangan oleh Momen Puntir

Lokomotif merupakan bagian dari kereta api dimana terdapat mesin untuk menggerakkan kereta api. Salah satu jenis dari kereta api di Indonesia yaitu menggunakan mesin diesel. Pada mesin diesel terdapat exhaust yang berfungsi sebagai saluran pembuangan gas emisi. Perawatan lokomotif memungkinkan terjadinya patah pada baut exhaust. Penelitian ini bertujuan untuk mengetahui penyebab kegagalan dari baut yang dipakai pada exhaust lokomotif diesel dengan meninjau perubahan struktur mikroskopik yang terjadi pada baut dengan kondisi temperature tinggi dan mengetahui distribusi tegangan yang terjadi pada baut pada saat pelepasan. Kondisi pada daerah exhaust lokomotif kereta api dapat mencapai diatas 750°C menyebabkan perubahan struktur kristal dari material pada baut. Modulus kegagalan punter lebih rawan terjadi pada material ulet. Material baut SAE grade 5 ukuran 1 inch memiliki nilai torsi maksimum material 885,8 N.m dengan nilai standardnya yaitu 664 N.m. Dengan demikian menunjukkan bahwa pada saat temperature ruang torsi yang diberikan pada saat pelepasan baut memiliki nilai yang aman, namun dengan meningkatnya temperature menurunkan nilai tegangan maksimum material baut untuk terdeformasi puntir

Finite Element Analysis of Road Roughness Effect on Stress Distribution of Heavy Duty Truck Chassis

Finite Element Method is one of the most powerful methods in numerical analysis techniques. The time consuming tasks and high costs can be reduced by using this method in the early stages of machine component design. The truck chassis is a base component of vehicles and integrates many of the truck component systems such as the axles, suspension, power train, cab and trailer. The truck chassis has been loaded by static, dynamic and also cyclic loading. Static loading comes from the weight of cabin, its contents and passengers. The movement of truck affects a dynamic loading to the chassis. The vibration of engines and the roughness of roads give a cyclic loading. The chassis used in trucks has almost the same appearance since models were developed 20 or 30 years ago, denoting that they are a result of slow and stable evolution of these frames throughout the years. The manufacturers of these chassis, in the past, and some still today, solve their structural problems by trial and error. Conducting experimental tests in the early stage of design are time consuming and expensive. In order to reduce these costs, it is important to conduct simulations using numerical software methods to find the optimum design. Determination of static, dynamic and fatigue characteristics of a truck chassis before manufacturing is important for design improvement. This paper presents the finite element analysis (FEA) of road roughness effects on stress distribution of heavy duty truck chassis

Test rig development for load test of pipe saddle support

Pipe saddle support is a structure commonly used to support horizontal steel pipe. It prevents direct contact between the pipe and the support. Pipe saddle support can experience displacement due to pipe movement and insufficient stress analysis. Given these concerns, conducting a load test is essential to determine the stress on pipe saddle supports. However, a universal testing machine (UTM) is not suitable for this purpose due to the size limitation. Therefore, this study proposed a test rig setup for the pipe saddle support load test. The test rig consists of a portal frame secured by an underground locking system featuring a strong floor. Additionally, an actual pipe is utilized to replicate actual loading conditions on the pipe saddle support. The applied load is measured using a load cell, with a custom-designed bracket to ensure precise load transfer. Finally, the pipe saddle support specimen is bolted to a base support to maintain stability during the load test. Stress analysis using finite element analysis (FEA) demonstrated that the test rig is suitable for conducting load tests on the specimens with a maximum force of 80 kN. FEA confirmed that the test rig operates within a safety factor of 1.3

Penggunaan metode Reliability-Centered Maintenance untuk menjaga keandalan material belt conveyor

Alat transportasi berperan penting dalam mengangkut material konsentrat untuk diolah dalam pabrik smelter secara kontinyu. Peralatan tersebut dijaga agar selalu beroperasi tanpa ada kerusakan. Kerusakan alat dapat mengakibatkan terhentinya proses produksi. Oleh karena itu manajemen peralatan pabrik sangat penting, dengan melakukan maintenance secara berkala untuk menghindari kejadian yang tidak diinginkan. Permasalahan yang sering terjadi pada salah satu alat yaitu belt conveyor adalah adanya tumpahan material ketika beroperasi. Penelitian ini menerapkan metode Reliability Centered Maintenance untuk mengetahui solusi yang tepat atas permasalahan sehingga material belt conveyor memiliki kehandalan yang tinggi dan umur pakainya meningkat. Hasil penelitian menunjukkan bahwa failure mode yang terjadi pada belt conveyor merupakan kategori C dan memiliki persentase terbesar sehingga dampak kerugian ekonominya relatif kecil. Namun tetap demikian kemungkinan terjadinya outage pada plant tetap harus diperhatikan

Vibration Training System Performance Test – Two Mass Absorber System Experiment

Two mass absorber is a vibration control system designed to enhance structural stability by strategically placing additional masses to effectively absorb and dampen vibrations. This technology mitigates resonance and harmful amplitude, reducing the risks of structural failure and operational inefficiencies in diverse engineering applications. Through this innovative approach, structures can withstand dynamic forces and operate efficiently in various fields. The TM 150 unit is used for conducting various experiments related to vibration phenomena. In this paper, experiments are carried out on a flexible beam that is oscillated using an unbalanced mass in the frequency range of 6 Hz to 18 Hz to see at which frequency the flexible beam will resonate. Another variation is to provide two mass absorbers under the flexible beam to see the difference. The experimental resonance graph was produced that was in accordance with the theoretical one, but with different amplitude units due to equipment limitations. The resulting graph shows before the absorber, the flexible beam resonates at its natural frequency. Afterward, small vibrations occur at that point, while resonance shifts. Furthermore, the performance of the vibration test unit is very good in showing the phenomena that occur in accordance with the theory

Minimizing Risk of Failure from Ceramic-on-Ceramic Total Hip Prosthesis by Selecting Ceramic Materials Based on Tresca Stress

The choice of ceramic-on-ceramic coupling in total hip prosthesis has advantages over couplings with other combinations of materials that use polyethylene and metal materials in terms of high hardness, scratch resistance, low wear rate, and increased lubrication performance. To reduce the risk of primary postoperative failure, the selection of ceramic materials for ceramicon-ceramic coupling is a strategic step that needs to be taken. The current study aims to analyze ceramic-on-ceramic coupling with commonly used ceramic materials, namely zirconium dioxide (ZrO2), silicon nitride (Si3N4), and aluminium oxide (Al2O3), according to Tressa failure criterion for the investigation of the stress distribution. A two-dimensional axisymmetric finite element-based computational model has been used to evaluate the Tresca stress on ceramic-on-ceramic coupling under gait cycle. The results show that the use of ZrO2-on-ZrO2 couplings can reduce Tresca stress by about 17.34% and 27.23% for Si3N4-on-Si3N4 and Al2O3-on-Al2O3 couplings, respectively

Tresca stress study of CoCrMo-on-CoCrMo bearings based on body mass index using 2D computational model

Many investigations for developing total hip arthroplasty performance presented in previous literature show focusing on implant users' external factors. Although this is important, assessing loading based on implant user’s weight also needs to be examined as it contributes to overall performance of this prosthesis. Our study attempted to evaluate Tresca stress in CoCrMo-on-CoCrMo hip implant based on body mass index from patient. 2D computational model in this paper has been establishing to reach this objective. Loading variation is also considered with different body mass index categories from underweight, normal, overweight, obese class I, obese class II, and obese class III under normal walking condition. We found that Tresca stress rises with higher body mass index category

Stress analysis of heavy duty truck chassis using finite element method

One of the most important steps in development of a new truck chassis is the prediction of fatigue life span and durability loading of the chassis frame. The age of many truck chassis in Malaysia are of more than 20 years and there is always a question arising whether the chassis is still safe to use. Thus, fatigue study and life prediction on the chassis is necessary in order to verify the safety of this chassis during its operation. Stress analysis using Finite Element Method (FEM) can be used to locate the critical point which has the highest stress. This critical point is one of the factors that may cause the fatigue failure. The magnitude of the stress can used to predict the life span of the truck chassis. In this study, the stress analysis is accomplished by the commercial finite element packaged ABAQUS