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Abstrak :
Micro Friction Stir Spot Welding (mFSSW) merupakan turunan dari proses Friction Stir Spot Welding (FSSW) yang dapat digunakan pada proses pengelasan pelat tipis. Sebagai proses pengelasan single spot, mFSSW dapat dipertimbangkan sebagai alternatif untuk menggantikan proses resistance spot welding dan paku keling. Spot welding sendiri sudah banyak digunakan pada industri aerospace, kereta api dan otomotif. Oleh karena itu, komponen yang di las menggunakan proses mFSSW perlu diketahui kekuatan sambungan nya terhadap beban dinamis. Penelitian ini bertujuan untuk mengetahui pengaruh geometri pahat terhadap ketahanan sambungan las yang dihasilkan melalui teknik pengelasan mFSSW pada pelat tipis kuningan dengan Aluminium AA1100 dalam bentuk beban berulang. Dalam penelitian ini parameter yang divariasikan berupa geometri tool, dimana tiap-tiap tool tersebut memiliki dimensi pin dan shoulder yang berbeda. Setelah di las dan dipastikan terbebas dari crack, spesimen akan di uji Tarik terlebih dahulu untuk mendapatkan parameter dan dilakukan uji fatigue. Hasil dari pengujian fatigue ini menghasilkan jenis kegagalan terhadap spesimen berupa pulled out nugget, dan juga terdapat fenomena fracture selama proses pengujian fatigue yaitu kerusakan spesimen selama pengujian diawali dengan adanya initial crack berupa hook dan diakhiri dengan final fracture. Selain itu berdasarkan pengujian fatigue yang telah dilakukan, didapatkan bahwa semakin tinggi pin tool, semakin kecil diameter tool dan juga semakin kecil luas penampang keyhole maka ketahanan fatigue semakin meningkat. Dan tool dengan geometri medium tapper  adalah jenis tool yang menghasilkan siklus terpanjang. ......Micro Friction Stir Spot Welding (mFSSW) is a derivative of the Friction Stir Spot Welding (FSSW) process that can be used in thin plate welding processes. As a single spot welding process, mFSSW can be considered as an alternative to replace resistance spot welding and rivet processes. Spot welding itself is already widely used in the aerospace, railroad and automotive industries. Therefore, components that are welded using the mFSSW process need to know the strength of the connection against dynamic loads. This study aims to determine the effect of tool geometry on the durability of welded joints produced through mFSSW welding techniques on brass thin plates with Aluminum AA1100 in the form of repeated loads. In this study, the parameters were varied in the form of tool geometry, where each tool has different pin and shoulder dimensions. After being welded and confirmed to be free from cracks, the specimens will be tensile tested first to obtain parameters and fatigue tests will be carried out. The results of this fatigue test resulted in a type of failure of the specimen in the form of a pulled out nugget, and there was also a fracture phenoma during the fatigue testing process, namely specimen damage during testing starting with an initial crack in the form of a hook and ending with a final fracture. In addition, based on the fatigue testing that has been carried out, it is found that the higher the tool pin, the smaller the tool diameter and also the smaller the keyhole cross-sectional area, the fatigue resistance increases. And the tool with medium tapper geometry is the type of tool that produces the longest cycle.

Abstrak :
Micro Friction Stir Spot Welding (mFSSW) merupakan turunan dari proses Friction Stir Spot Welding (FSSW) yang dapat digunakan pada proses pengelasan pelat tipis. Sebagai proses pengelasan single spot, mFSSW dapat dipertimbangkan sebagai alternatif untuk menggantikan proses resistance spot welding dan paku keling. Spot welding sendiri sudah banyak digunakan pada industri aerospace, kereta api dan otomotif. Oleh karena itu, komponen yang di las menggunakan proses mFSSW perlu diketahui kekuatan sambungan nya terhadap beban dinamis. Penelitian ini bertujuan untuk mengetahui pengaruh geometri pahat terhadap ketahanan sambungan las yang dihasilkan melalui teknik pengelasan mFSSW pada pelat tipis Aluminium AA1100 dalam bentuk beban berulang. Dalam penelitian ini parameter yang divariasikan berupa geometri tool, dimana tiap-tiap tool tersebut memiliki dimensi pin dan shoulder yang berbeda. Setelah di las dan dipastikan terbebas dari crack, spesimen akan di uji fatigue dengan 7 beban berbeda di tiap-tiap pengujian per hasil lasan dari tiap-tiap tools dengan menggunakan 2 kali repetisi. Hasilnya akan diolah menjadi S-N diagram dan kerusakan tiap spesimen dianalisis untuk mengetahui geometri pahat mana yang memiliki ketahanan paling baik terhadap beban berulang. Hasil penelitian menunjukkan bahwa tool yang tidak memiliki pin menghasilkan siklus terpanjang. Hal ini dikarenakan hasil las dari tool tersebut memiliki profil hook yang lurus dan memiliki nilai effective top sheet thickness yang cukup besar, sehingga menyebabkan perambatan crack terjadi dalam waktu yang relatif lama. ...... Micro Friction Stir Spot Welding (mFSSW) is a derivative of the Friction Stir Spot Welding (FSSW) process which can be used in thin plate welding processes. As a singlespot welding process, mFSSW can be considered an alternative to applying resistance spot welding and rivet processes. Spot welding itself has been widely used in the aerospace, railway, and automotive industries. Therefore, components that are welded using the mFSSW process need to know their welding joint strength against dynamic loads. This study aims to determine the effect of tool geometry on the resistance of welded joints produced through the mFSSW on AA1100 Aluminum thin plates in the form of repeated loading. In this study, the parameters varied in the form of tool geometry, where each tool has different pin and shoulder dimensions. After welding and ensuring that it is free from cracks, the test object will be tested for fatigue with 7 different loads in each test per weld result of each tool using 2 repetitions. The results will be processed into an S-N diagram and the damage to each specimen is analyzed to determine which tool geometry has the best resistance to repeated loads. The results showed that the tool that did not have pins produced the longest cycle. This is because the welding results from this tool have a straight hook profile and have a large enough effective top sheet thickness value, thus causing crack propagation in a relatively long time.

Abstrak :
Physical behavior of models can be measured in the laboratory, which, in turn are often used to assess the behavior of more complicated structures. Mechanical responses present physical behavior of a structure. By using three different transducer, one can measure acceleration, velocity and displacements directly. Determination of velocity and displacements from acceleration data is preferable from point of view economics; but on the other hand this procedure, at present, is still causing problem. This study shows that displacements and velocity can be calculated from its acceleration which is obtained by using one transducer. The acceleration data are obtained from a cantilever steel plate which is subjected to a transient force at a discrete location on its surface or an initial deflection on its tip. An acquisition program was first designed before starting the experimental program. By means of a piezoelectric accelerometer, a conditioning amplifier and a digital oscilloscope, acceleration data are captured and then transferred to a personal computer. The transformation of these two responses, displacements and velocity from the acceleration data are performed in two domains, time domain and frequency domain. Two integration techniques, Newton-Cotes formula and Simpson's rule were used for the calculation in the time domain. For both techniques, adjustment of basis line is performed by End Zero Time Technique Modified. Programmation has been done for both types of domain analysis. The Simpson's rule gives sufficient results and Newton-Cotes formulation gives good results only for moderate values of Cotes coefficient. High values of the coefficient give unrealistic calculated velocity and displacements. Drifting character are present on the displacements calculated by both methods. In the frequency domain, the velocity and displacements are obtained from acceleration data by means of Fast Fourier Transform and its Inverse Fourier Transform. This method give satisfactory results only for the calculation of velocity. The displacements obtained show also drifting character. Nevertheless, realistic forms of this displacements are moderately accepted. Results comparison of the two methods, both in time domain and frequency domain, show that none of the method is better than another. Analysis in frequency domain give more accurate results, but this method is not definitely a principal method for the solution of this type of problems. The two methods shall be used for the calculation of velocity and displacements. This procedure can verify one result to another to avoid wrong interpretation of transformed responses.

Abstrak :
ABSTRAK
Proses Micro Friction Stir Spot Welding (mFSSW) merupakan teknik pengelasan pelat logam yang memiliki ketebalan pelat yang relatif tipis. mFSSW memiliki keunggulan dalam proses pengelasan dibandingkan dengan pengelasan konvensional, seperti Arc Welding. Keunggulannya adalah dari segi kualitas pengelasan yang lebih baik dan distorsi yang relatif rendah. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh bentuk pahat dan kedalaman pahat terhadap sifat mekanik dan geometri hasil lasan pada teknik pengelasan Micro Friction Stir Spot Welding (mFSSW) menggunakan pelat tipis aluminium A1100. Pada penelitian ini parameter yang divariasikan adalah geometri pahat dan kedalaman pahat. Parameter geometri pahat divariasikan dalam penelitian ini menjadi 7 jenis geometri pahat. Parameter kedalaman puncture divariasikan dalam penelitian ini menjadi 3 macam kedalaman (200 mikron, 400 mikron, dan 600 mikron). Uji makro dilakukan untuk mengetahui geometri las, yaitu profil kontur, diameter, dan kedalaman sambungan. Hasil uji makro dilakukan untuk memprediksi hasil dan kekuatan patah. Untuk mengetahui sifat mekanik dilakukan dua pengujian yaitu uji tarik dan uji tarik silang. Hasil uji tarik akan dianalisa untuk menentukan jenis patahan dan kekuatannya. Dari hasil percobaan dan analisis diketahui bahwa geometri pahat dan kedalaman tusukan akan menghasilkan karakteristik tersendiri untuk geometri las dan kekuatan las. Geometri las yang akan terlihat pada profil adalah shoulder, pin, TMAZ, dan kedalaman aktual yang dihasilkan. Kekuatan las atau sifat mekanik yang akan diketahui adalah tegangan

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ABSTRACT
The Micro Friction Stir Spot Welding (mFSSW) process is a metal plate welding technique that has a relatively thin plate thickness. mFSSW has advantages in the welding process compared to conventional welding, such as Arc Welding. The advantages are in terms of better welding quality and relatively low distortion. The purpose of this study was to determine the effect of chisel shape and chisel depth on the mechanical properties and geometry of the welds in the Micro Friction Stir Spot Welding (mFSSW) welding technique using A1100 aluminum thin plates. In this study, the parameters that were varied were tool geometry and tool depth. The tool geometry parameters were varied in this study into 7 types of tool geometry. The parameters of the puncture depth were varied in this study into 3 different depths (200 microns, 400 microns, and 600 microns). The macro test was carried out to determine the weld geometry, namely the contour profile, diameter, and joint depth. Macro test results were performed to predict yield and fracture strength. To determine the mechanical properties, two tests were carried out, namely tensile test and cross-tensile test. Tensile test results will be analyzed to determine the type of fracture and its strength. From the experimental results and analysis, it is known that the tool geometry and the depth of the puncture will produce its own characteristics for the weld geometry and weld strength. The weld geometry that will be seen in the profile is the shoulder, pin, TMAZ, and the actual resulting depth. Weld strength or mechanical properties that will be known is the stress