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Abstrak :
Recently, advanced technologies have put much attention on the materials selection as an alternative way to reduce the weight of material. Taking into account electronic devices, automobiles, aeronautics, and structural applications they are all required immense raw product. Magnesium and its alloys as one of the lightest metal (p = 1.8 g/m3) has attracted much intentions for an alternative metal alloy. Such good properties owned in magnesium including good castability, good machinability as well weldability and considerably cheap have made more convenient way for magnesium alloys to be used. However, its poor formability at room temperature is the major drawback of this material. Therefore, this project is intended to investigate the properties of AZ31 magnesium alloy especially for uniaxial tensile test at relatively low strain rate. Tensile properties were observed on the yield strength and elastic modulus which seems the crucial factor for magnesium tested at relatively low temperature. Slight dependency of plate orientations to the tensile properties for plate samples and tensile directions for sheet samples with three different sample thicknesses were also carried out. The experiment was done with the use of non-contact extensometer of Mini Instron Tensile Test. The main conclusion from the present study is that the thickness and the samples orientations affected tensile direction properties of the sheet samples. Microyielding occurred during the test which resulted in declining of modulus as the thickness increases. By contrast ultimate tensile strength, yield strength and ductility are generally increased as the thickness increased.

Abstrak :
This paper describes the material parameter determination procedure for the elastoviscoplastic bodner-partom model.....

Abstrak :
ABSTRAK 3D Printing belakangan ini telah menjadi salah satu pilihan terbaik untuk memanufaktur suatu produk karena kemampuannya untuk menghasilkan bentuk yang kompleks dengan biaya yang tergolong murah. Selain itu, pemilihan material dalam proses manufaktur merupakan proses penting yang harus dilaksanakan. Dengan memadukan Thermoplastic Polyurethane (TPU) dan Polylactic Acid (PLA) filamen, diharapkan dapat menghasilkan material baru dengan properti yang lebih tinggi dibandingkan material aslinya. Kedua material ini tergolong sebagai material yang biodegradable dan biocompatible yang aman saat berhubungan langsung dengan makhluk hidup. Dibandingkan dengan Polylactic Acid, Thermoplastic Polyurethane memiliki elongation at break yang lebih tinggi. Jadi, dengan menggabungkan dua material ini menggunakan struktur komposit untuk metode 3D Printing yaitu sistem penguncian dengan mencetak material sisi demi sisi, material baru akan dihasilkan. Komposisi TPU dan PLA adalah TPU/PLA: 10%/90%; TPU/PLA: 20%/80%; TPU/PLA: 30%/70%; TPU/PLA: 35%/75%, TPU/PLA: 40%/60% secara berurutan. Properti mekanik dari material ini dinilai dari uji Tarik. Hasilnya adalah, Kekuatan Tarik: 45.42033 MPa, 44.73766 MPa, 50.03833 MPa, 48.7633 MPa, dan 51.0130 MPa untuk 10%, 20%, 30%, 35%, and 40% matrix material, berurutan. Elongasi: 18.71%, 16.33%, 17.06%, 16.93%, dan 17.09% untuk 10%, 20%, 30%, 35%, and 40% matrix material, berurutan. Modulus Elastisitas: 421.88 MPa, 420.19 MPa, 485.23 MPa, 462.22 MPa, dan 495.22 MPa untuk 10%, 20%, 30%, 35%, and 40% matrix material, berurutan. Kekuatan Yield: 44.81 MPa, 44.73 MPa, 50.03 MPa, 45.35 MPa, and 50.43 MPa untuk 10%, 20%, 30%, 35%, dan 40% matrix material, berurutan.

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ABSTRACT 3D Printing has become one of the best choices for manufacturing a product lately, due to its ability to produce a complex shape with an approximately low cost needed. On the other hand, material selection is always be an important step before doing any manufacturing process. By combining Thermoplastic Polyurethane and Polylactic Acid filament new material with higher properties than the original material is expected and can be one of the best choices of material to produce a medical related product. Both of these material are considered as a biodegradable and biocompatible material that is safe in contact with living issues. Thermoplastic Polyurethane has a higher elongation at break in compare to Polylactic Acid. So by combining these two material using a composite structure for 3D printing method which is the interlocking printing system by printing two different material side by side, a new material is produced. The Thermoplastic Polyurethane compositions are TPU/PLA: 10%/90%, TPU/PLA: 20%/80%, TPU/PLA: 30%/70%, TPU/PLA: 35%/75%, TPU/PLA: 40%/60% respectively. The mechanical properties of this new material were assessed by a tensile test. The results are Ultimate Tensile Strength 45.42033 MPa, 44.73766 MPa, 50.03833 MPa, 48.7633 MPa, and 51.0130 MPa for 10%, 20%, 30%, 35%, and 40% matrix material, respectively. Elongation at Break: 18.71%, 16.33%, 17.06%, 16.93%, and 17.09% for 10%, 20%, 30%, 35%, and 40% matrix material, respectively. Elastic Modulus: 421.88 MPa, 420.19 MPa, 485.23 MPa, 462.22 MPa, and 495.22 MPa for 10%, 20%, 30%, 35%, and 40% matrix material, respectively. Yield Strength: 44.81 MPa, 44.73 MPa, 50.03 MPa, 45.35 MPa, and 50.43 MPa for 10%, 20%, 30%, 35%, and 40% matrix material, respectively.

Abstrak :
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 ......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).

Abstrak :
Telah dilakukan penelitian untuk membuat material komposit dengan menggunakan poxy sebagai matriks dan woven roving E-Glass sebagai fiber. Pembuatan material enggunakan metode Vacuum Assisted Resin Infussion (VARI). Material dibuat dengan struktur serat terjalin 0°, 45°, dan -45° yang disusun sebanyak tujuh lapis. Uji tarik dilakukan untuk mengukur kekuatan mekanik material dan membandingkannya dengan hasil perhitungan menggunakan MATLAB 7.0.1. Pengujian dilanjutkan dengan penyinaran ultraviolet-A pada panjang gelombang 340nm yang lama penyinarannya divariasikan selama 10 jam, 20 jam, dan 30 jam. Kemudian, dilakukan kembali uji tarik dan didapatkan penurunan kuat tarik maksimum sebesar 28,22% sesudah penyinaran 30 jam, sedangkan modulus elastisitas relatif tidak berubah. Kerusakan yang terjadi akibat penyinaran pada ermukaan fiber dan matriks dilihat dengan menggunakan Scanning Electron Microscope (SEM). ......An experiment to make composites using epoxy as a matrix and woven roving E-Glass as a fiber was produced by a Vacuum Assisted Resin Infusion (VARI) method. The laminate systems consisted of seven woven fiber laminas with a pattern of 0°, 45°, and -45° degrees of orientation. Tensile properties of composites were obtained and compared with the result of MATLAB 7.0.1 program calculation The specimens were exposed by an ultraviolet-A (λ=340nm) with exposure period of 10, 20, and 30 hours The environmental tested specimens were followed by tensile test. The Ultimate Tensile Stress (UTS) of the composite decreased by 28,22% after 30 hours exposure. However, there was no reduction in the stiffness values. The Failure surfaces of specimen were observed using Scanning Electron Microscope. Failure was dominated with matrix rupture in transverse direction.

Abstrak :
Pengujian tarik masih banyak dilakukan dengan metode eksperimental yang memerlukan waktu dan biaya yang tidak sedikit. Namun, hal itu dapat diatasi dengan menggunakan pendekatan numerik dimana pengujian tarik disimulasikan kedalam suatu komputer dengan menggunakan metode elemen hingga. Penelitian ini bertujuan untuk mengetahui pengaruh elemen dan jumlah nodal pada pemodelan uji tarik pelat isotropik dengan pembebanan uni-aksial. Elemen yang digunakan ialah elemen 4 titik dengan jumlah nodal 196 dan 676 dan elemen 8 titik dengan jumlah nodal 560 dan 1976. Hasil pemodelan menunjukkan bahwa semakin banyak jumlah nodal maka hasil pemodelan akan semakin akurat. Hasil yang didapatkan ialah pemodelan dengan menggunakan elemen 8 titik dan jumlah nodal 1976 memberikan hasil yang akurat dengan persentase kesalahan 1,37 %. ......Tensile test was mostly done by experimental methods that require much times and costs. However, it can be solved by using a numerical approach in which the tensile test is simulated into a computer using the finite element method. This research aims to know effect of element and number of nodes in modeling tensile test of isotropic plate with uni-axial loading. Element used in this research is 4-nodes element with 196 and 676 number of nodes and 8-nodes element with 560 and 1976 number of nodes. The modeling results indicate that the more number of nodes then the modeling results will be more accurate. The results of this modeling is a modeling using 8-nodes element with 1976 number of nodes give an accurate result with a percentage of error 1.37%.

Abstrak :
The 7075 aluminum alloy (a typical Al–Zn–Mg–Cu alloy) is one of the most important engineering alloys. It is mainly used in the automotive industry, in transport and aeronautics, due to its excellent strength/weight ratio. The purpose of the present research is to model the behavior of 7075 aluminum alloy and to build an experimental database to identify the model parameters. Firstly, the paper presents an experimental device of simple tensile tests and the studied material on 7075 aluminum alloy. Thus, uniaxial tensile tests are carried out in three loading directions relative to the rolling direction. From experimental hardening curves and Lankford coefficients, the mechanical properties are extracted, particularly the various fractures owing to pronounced anisotropy relating to the material. Secondly, plastic anisotropy is then modeled using the identification strategy which depends on yield criteria, hardening and evolution laws. By smoothing experimental hardening curves in the tensile tests, a selection is made in order to choose the most appropriate hardening law for the identification of the studied material. Finally, a comparison with experimental data shows that the behavior model can successfully describe the anisotropy of the Lankford coefficient.

Abstrak :
Studi ini membandingkan hasil pengelasan plat aluminium seri 5083 dengan ketebalan 6 mm menggunakan Friction Stir Welding (FSW) dengan variasi welding speed, yaitu 22, 29 dan 38 mm/menit dengan hasil pengelasan konvensional Gas Tungsten Arc Welding (GTAW). Pengelasan FSW dilakukan dengan menggunakan mesin frais. Hasil FSW dan GTAW diidentifikasi menggunakan uji tarik, uji kekerasan, struktur mikro dan SEM-EDS. Dari identifikasi hasil analisa struktur mikro dan SEM-EDS menunjukkan terbentuknya presipitat Mg2Si dan alumina (Al2O3) yang menyebabkan naiknya nilai kekerasan pada daerah Lasan. Kemudian dari hasil pengujian struktur mikro diperoleh grain size hasil pengelasan FSW lebih kecil dari GTAW. Hal ini menyebabkan kekerasan hasil FSW lebih tinggi dibandingkan dengan GTAW. Berikutnya dari analisa struktur makro diperoleh bahwa semua hasil pengelasan FSW terdapat cacat incomplete fusion yang diakibatkan oleh kurang sempurna proses pengelasan. Hal ini mengakibatkan hasil pengujian tarik GTAW lebih baik dari FSW. ......This study compares the results of welding 5083 series aluminum plate with a thickness of 6 mm using the Friction Stir Welding (FSW) with a variation of welding speed, namely 22, 29 and 38 mm / min with the results of conventional welding Gas Tungsten Arc Welding (GTAW). FSW welding is done by using a milling machine. Results FSW and GTAW identified using tensile test, hardness test, microstructure and SEM-EDS. The identification results of the analysis of microstructure and SEM-EDS showed the formation of precipitates Mg2Si and alumina (Al2O3) which resulted in higher hardness values at weld zone. Then the microstructure of the test results obtained FSW welds grain size smaller than GTAW. It causes hardness of FSW results higher than the GTAW. The next of the macro structure analysis showed that all FSW welds are incomplete fusion defects caused by imperfect welding process. This resulted in GTAW tensile test results better than FSW.

Abstrak :
Roket adalah kendaraan peluncur yang mampu mengangkut muatan ke tujuan yang diinginkan. Nosel merupakan komponen struktural terberat, yaitu menyumbang sekitar 30 % dari berat keseluruhan struktur roket sehingga sangat terbuka kemungkinan untuk mereduksi beratnya, dalam mendesain nosel juga harus memperhatikan beban mekanik dan termal yang cukup tinggi akibat dari pembakaran propelan untuk menghasilkan gaya dorong (thrust) roket. Salah satu alternatif untuk mereduksi berat adalah penggunaan material Komposit Polimer Berpenguat Serat Karbon, untuk mengaplikasikan material komposit tersebut terhadap nozzle case, perlu dilakukan karakterisasi sifat-sifat mekanik. Salah satu pengujian yang paling sering dilakukan yaitu uji tarik (tensile test), pengujian ini memiliki fungsi untuk mendapatkan nilai kekuatan, modulus elastisitas, dan failure mode. Pengujian Tarik dilakukan melalui dua tahapan untuk menyeleksi material yang mampu menerima beban termal. Pengujian tarik tahap pertama dilakukan dengan rentang temperatur dari RT sampai 200°C menggunakan mesin Shimadzu AG-50KNX PLUS Machine untuk seleksi material antara komposit C/LY5052 dengan C/ARMC berdasarkan ketangguhan pada temperature yang diuji. Selanjutnya material yang terpilih diteruskan ke pengujian tahap dua, dimana material terpilih di uji Tarik pada rentang temperatur RT sampai 800°C dengan interval 100°C menggunakan mesin SCHENK TREBEL Machine. Hasil yang didapatkan pada penelitian ini, untuk gangguan mekanik pada nozzle case maksimum sebesar 7 MPa, beban mekanik ini sangat kecil jika dibandingkan dengan kekuatan tarik yang dimiliki komposit C/LY5052 dan C/ARMC, untuk beban termal pada Nozzle Case, pemanasan maksimum yang terjadi pada nozzle Case dengan rentang temperature 550ºC hingga 700°C, pada temperatur ini komposit C/LY5052 tidak bisa diterapkan karena hanya mampu bertahan sampai temperatur 200 ºC, hasil berbeda pada komposit C/ARMC pada saat rentang temperatur ini masih tangguh, maka dari hasil tersebut komposit C/ARMC dalam penelitian ini dapat dijadikan acuan sebagai alternatif material Nozzle Case. Namun ketika mendesain nozzle case dengan material komposit C/ARMC harus diperhatikan mode kegagalannya terutama mode kegagalan delaminasi. ......A rocket is a launch vehicle capable of transporting payload to the desired destination. The nozzle is the heaviest structural component, which contributes about 30% of the total weight of the rocket structure so it is very possible to reduce the weight. In designing the nozzle, one must also pay attention to the mechanical and thermal loads that are quite high due to the combustion of the propellant to produce rocket thrust. One alternative to reduce weight is the use of Carbon Fiber Reinforced Polymer Composite materials, to apply these composite materials to the nozzle case, it is necessary to characterize the mechanical properties. One of the most frequently performed tests is the tensile test. This test has a function to obtain values for strength, modulus of elasticity, and failure mode. Tensile testing is carried out in two stages to select materials that are capable of receiving thermal loads. The first stage of the tensile test was carried out with a temperature range from RT to 200°C using the Shimadzu AG-50KNX PLUS Machine for material selection between C/LY5052 and C/ARMC composites based on toughness at the temperature tested. Then the selected material is continued to the second stage of testing, where the selected material is tested in Tensile at a temperature range of RT to 800°C with intervals of 100°C using the SCHENK TREBEL Machine. The results obtained in this study, for maximum mechanical disturbance in the nozzle case of 7 MPa, this mechanical load is very small when compared to the tensile strength of the C/LY5052 and C/ARMC composites, for the thermal load on the Nozzle Case, the maximum heating that occurs on the Case nozzle with a temperature range of 550ºC to 700°C, at this temperature the C/LY5052 composite cannot be applied because it can only survive up to a temperature of 200 ºC, the results are different for the C/ARMC composite when this temperature range is still tough, so from these results, The C/ARMC composite in this study can be used as a reference as an alternative nozzle case material. However, when designing the nozzle case with C/ARMC composite material, the failure mode must be considered, especially the delamination failure mode.