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"Tujuan penelitian ini adalah untuk mempelajari hubungan antara proses penggilingan karet dan karakteristik vulkanisasi karet alam. Analisiskarakteristik vulkanisasi dilakukan dengan merancang formula karet alam yang dimastikasi dan digiling, kemudian diikuti dengan pengamatan reaksi vulkanisasi. Ada empat metode mastikasi yang masing-masing metode diikuti oleh empat urutan proses pencampuran karet. Metode pertama, karet dimastikasi selama 5 menit dan kemudian diikuti penambahan bahan kimia karet dan carbon blackN 330 secara simultan. Metode kedua dan ketiga, karet dimastikasiselama 1 menit kemudian carbon black dan bahan kimia karet ditambahkan secara simulan tetapi menggunakan bahan mengisi dengan tipe yang berbeda. Metode keempat, karet dimastikasi selama 3 menit dan kemudian carbon black ditambahkan dahulu lalu diikuti dengan penambahan bahan kimia karet. Penambahan bahan kimia karet dan carbon black ke dalam karet dibedakan atas urutan dan waktu yang dibutuhkan untuk masing-masing proses pencampuran.Carbon black ditambahkan dalam dua kali, yang pertama 10 phr ditambahkan kemudian sisa carbon black 40 phr ditambahkan kemudian bersamaan dengan penambahan minyak. Metode yang lain, nisbah penambahan carbon black (penambahn pertama dan penambahan kedua bersamaan dengan minyak) adalah 20:30, 30:20, dan 40:10. Hasilnya menunjukkan bahwa proses penggilingan karet mempengaruhi perubahan karakteristik vulkanisasi. Ini dipengaruhi oleh metode penambahan carbon black. Suhu penggilingan juga mempengaruhi waktu dan laju vulkanisasi, di mana semakintinggi suhu penggilingan, semakin rendah waktu dan laju vulkanisasi. Suhu vulkanisasi juga mempengaruhi waktu dan laju vulkanisasi dengan semakin tinggi suhu vulkanisasi, semakin rendah waktu vulkanisasi dan semakin tinggi laju vulkanisasi. Selanjutnya, ukuran partikel carbon black juga mempengaruhi waktu dan laju vulkanisasi di mana semakinkecil ukuran partikel, semakin rendah waktu vulkanisasi dan semakin tinggi laju vulkanisasi.

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AbstractThis research is aimed at studying the relationship between rubber mixing processes and curing characteristics of natural rubber. The curing characteristic analysis was carried out through a natural rubber formula having been masticated and mixed, followed by curing. As many as four mastication methods were finely applied; each respected four sequences of rubber mixing process. In the first method, rubber was masticated for 5 minutes and then rubberchemicals and carbon black N 330 were simultaneously added. In the second and the third methods, rubber was masticated for 1 minute and then carbon blacks and rubber chemicals were also simultaneously added but using different type of fillers. In the fourth method, rubber was masticated for 3 minutes and then rubber chemicals andcarbon black were subsequently added. The additions of rubber chemicals and carbon blacks to the masticated rubberwere distinguished by the sequence and time allocated foreach mixing process. The carbon blacks were added in twostages by which 10 phr was added first and the remaining 40 phr was added later along with oil. In another method, ratios of the carbon blacks addition (as done in the first and the second stages) were 20:30, 30:20, and 40:10. The examination results showed that rubber mixing process gave an impact on the changes of curing characteristics. They were much affected by the method of carbon black addition. The mixing temperature also had an effect on both curing time and curing rate in which the higher the mixing temperature, the lower the curing time and curing rate. Vulcanizationtemperature also affected the curing time and curing rate in which the higher the vulcanization temperature, the lower the curing time and the higher the curing rate. Lastly, particle size of carbon black also gave an impact on the curing time and curing rate in which the smaller the particle size, the lower the curing time and the higher the curing rate."

"Timbunan bertiang merupakan salah satu metode dalam meningkatkan daya dukung tanah lunak ketika dilakukan pekerjaan penimbunan, dimana tanah dasar diberikan perkuatan berupa pondasi tiang. Adapun dengan adanya perkuatan pada tanah lunak ini ternyata dapat mengurangi penurunan yang terjadi. Hal ini disebabkan oleh adanya mekanisme arching effect yang menyebabkan sebagian beban timbunan ditransfer ke pondasi tiang, sehingga tanah lunak mengalami reduksi beban. Penelitian ini merupakan turunan dari penelitian timbunan bertiang, dimana pada penelitian ini akan dianalisis perbedaan antara pondasi tiang yang menggunakan gesekan antara pondasi tiang dan tanah (friction piles) dengan pondasi tiang dengan menggunakan tahanan ujung (end bearing piles), dimana digunakan Program Plaxis 3D Foundation dalam permodelannya. Selain itu, studi ini juga memvariasikan ketinggian timbunan, jarak antar tiang, kekakuan aksial lapisan geosintetik, dan juga susunan pondasi tiang sehingga dapat terlihat pengaruhnya terhadap sistem timbunan bertiang ini. Bahasan dalam penelitian ini mencakup penurunan dan juga prilaku konsentrasi tegangan yang terjadi pada timbunan bertiang, serta pengaruhnya terhadap gaya tarik geosintetik yang terjadi pada pondasi tiang.

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Piled embankment is one of the methods to improve soft soil’s bearing capacity when the embankment construction is done, in which the base soil is given piles as the support. With piles support the soft soil, the settlement of the embankment can be reduced. This is because of the arching effect mechanism which causes some of the loads of the embankment are transfered through the piles, so that the load working on soft soil is reduced. This study is a derivative of piled embankment case study, where this study will analyze the differences of behaviour between the friction piles system and end bearing piles system using Plaxis 3D Foundation for modeling the case. Besides that, this study is also varying the height of embankment, the spacing between piles, the axial stiffness of geosynthetic layer, and the arrangement of piles so that the affection against piled embankment system could be concluded. The discussion of this research concludes the settlements and also the stress concentration behaviour, and also the axial force of geosynthetic layer that occurs in the piled embankment system."

"Friction-vibration interactions are common but important phenomena in science and engineering. Handbook of friction-vibration Interactions introduces the principles and provides the resources to understand and work with them. A unified theoretical framework includes some of the most important engineering applications. The first three chapters in the book introduce basic concepts and analytical methods of friction and vibration. The fourth chapter presents the general principles on friction-vibration interactions, and also touches on various engineering applications. In the fifth chapter the concepts and methods are extended to some of the most critical engineering applications in high-tech industry, presenting the friction-vibration interaction principle and applications in data storage systems."

"This book covers the rapidly growing area of friction stir welding. It also addresses the use of the technology for other types of materials processing, including super-plastic forming, casting modification, and surface treatments."

"Friction Stir Welding (FSW) adalah suatu teknologi pengelasan yang merupakan proses solid-state joining yang bisa digunakan untuk menyambungkan material yang berbeda, karakter awal base material bisa dipertahankan dan juga tidak memerlukan bahan tambah (filler). Distorsi dari hasil proses FSW sangat rendah dikarenakan prosesnya dalam keadaan padat sehingga defleksi setelah pengelasan bisa diminimalisir dengan kekuatan sebanding dengan proses pengelasan lain dan juga dapat diaplikasikan pada material-material yang sulit dilas bila menggunakan metode konvensional atau teknik penyambungan lain seperti solder atau rivet. Tipe sambungan pada FSW yang akan dilakukan adalah tipe Lap Welding dan Spot Welding. Adapun parameter yang akan digunakan adalah kecepatan putaran tool, kecepatan translasi tool (feeding), kemiringan tool saat proses pengelasan, dan desain mata pisau tool. Mesin yang digunakan pada proses ini yaitu mesin CNC tipe adjustable vertical milling machine sehingga hasil tiap langkah proses pengelasan akan seragam Untuk mengetahui kekuatan mekanik dari spesimen maka dilakukan uji kekasaran permukaan (surface rougness) dan uji tarik untuk setiap specimen yang berbeda tiap parameternya. Hasil analisis data dengan menggunakan metode Grafik, Chi Square, dan Response Surfece Methodology (RSM) menunjukkan bahwa setiap parameter yang digunakan pada proses FSW mempengaruhi kekuatan mekanik dan kekasaran permukaan pada material hasil pengelasan.

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Friction Stir Welding (FSW) is a welding technology which is a solid-state joining process that can be used to connect different materials. The initial character of the base material can be maintained and also does not require the added material (filler). Distortion of the FSW process is very low due to the process in the solid state so that the deflection after welding can be minimized with the strength compare to other welding processes, FSW can also be applied to materials that are difficult to weld when using conventional methods or other sewing techniques such as Solder or Rivet.

In this study, the type of connection with FSW method are Lap Welding and Spot Welding. The parameters were the tool rotation speed, translational speed of the tool (feeding), the slope of the tool when the welding process, and tool shape. Machine that used in this process was the adjustable CNC vertical milling machine so that the results of each step of the welding process will be uniform. To find the mechanical strength of the performed test specimens surface roughness and tensile test for each different specimens each parameter were investigated.

The results of data analysis using Graph Method, Chi Square, and Response Surface Methodology (RSM) showed that each parameter used in the FSW process influences to mechanical strength and surface roughness of welded materials."

"Micro Friction Stir Spot Welding (m-FSSW) merupakan salah satu jenis solid state welding dengan menggunakan non-consumable tool ber-skala mico thicknes material<1 mm) dan memanfaatkan gesekan serta axial force pada prosesnya. Hasil pengelasan yaitu lap-joint pada satu titik. Pada penelitian ini dilakukan pengujian Geometril tool terhadap hasil pengelasan, sehingga didapartkan korelasi antara geometri tool, temperature ,perubahan kecepaatn putar, hasil uji tarik geser dan uji hardness . Dimana semakin tinggi pin maka semakin tinggi RPM,temperature dan uji tarik (berbanding lurus) dimana ketinggian pin < plunge dept (600 µm). Namun Pada tool 4 geometri tool memiliki ketinggian pin 650 µm dan diameter 2.540 mm, sehingga membuat RPM masih di putaran tinggi ,temperatur pada suhu yang rendah dan hasil uji tarik yang belum maksimal (penetrasi hanya dilakukan di pin/Shoulder tidak menyentuk spesimen uji). Pada eksperimen ini peak temperatur tertinggi berada pada tool 3 (shoulder 450) dengan temperature 428.44˚C dengan hasil uji tarik geser yaitu 449.66 N (tertinggi). Pada pengujian tarik geser terdapat mode kegagalan diamati selama TS tes, yaitu mode PF (Pulled Out Nugget) pada seluruh hasil lasan dengan menggunakan tool 1 hingga tool 4. Hasil kekerasan pada geometri tool diketahui bahwa semakin tinggi pin maka hardnes akan semakin besar atau selaras dengan temperature yang terjadi. Namun saat temperatur berada pada suhu 400°C , material AA100 mengalami fully aneling sehingga berdampak pada penurunan hardness pada material hasil lasan (Jaehyung Cho ,2010). Pada hasil uji struktur makro (crossection) terdapat daerah Stir Zone (SZ), Thermo-Mechanically Affected Zone (TMAZ), Heat Affected Zone (HAZ),ParentMetal (PM), Hook dan EXTD zone (pada tool 1,2,3).Dimana daerah SZ (stir zone), terjadi rekristalisasi secara penuh (>350°C) sedangkan daerah TMAZ yang mengalami rekristalisasi sebagian akibat adanya panas dan mengalami perubahan sifat mekanik (250°C-350°C). dan untuk daerah HAZ atau daerah yang terpengaruhi panas namun

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Micro Friction Stir Spot Welding (m-FSSW) is a type of solid-state welding using a non-consumable tool with a mico scale (materialthickness < 1mm), using friction and axial force in the process. The result of welding is a lap joint at one point. This study has a correlation between tool geometry, temperature, rotational speed, tensile shear test, and hardness (Vickers) test. Where the higher the pin have higher the RPM, temperature, and tensile shear test (directly proportional) where the pin height < plunge depth (600 m). However, in tool 4 the geometry of the tool has a pin height of 650 m and a diameter of 2.54 mm so that the RPM is still at high rotation, the temperature is at a low temperature and the tensile shear results are not maximized (penetration is only at the pin/shoulder not touching the specimen). In this experiment, the highest peak temperature at tool 3 (shoulder 450) is about 428.44˚C with the results of the shear tensile test being 449.66 N (the highest). In the tensile shear test, get a failure mode, there is PF (Pulled Out Nugget) on all weld results (tools 1 to tool 4). The results of the hardness on the geometry of the tool are known that the higher pin, get the high hardness or proportional with the temperature that occurs. However, when the temperature is was at 400 °C, this material (AA100) had fully annealed and had an impact on decreasing the hardness of the welded material (Jaehyung Cho, 2010). In the macrostructure test results, there are Stir Zone (SZ), Thermo-Mechanically Affected Zone (TMAZ), Heat Affected Zone (HAZ), ParentMetal (PM), Hook, and EXTD zone (on tool 1,2,3). The SZ region (stir zone), where full recrystallization occurs (>350 °C) while the TMAZ region partially recrystallizes due to heat and changes in mechanical properties (250 °C-350 °C). and for the HAZ region or heat-affected region but not recrystallized (<250 °C)."