Shabrina, Hilaliyah Nur (2017) Pemodelan Kasus Unbalance pada Centrifugal Fan saat Sebelum dan Sesudah Pemasangan DVA. Undergraduate thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Di dalam operasi permesinan sering kali terjadi getaran. Hal ini disebabkan oleh satu dan berbagai hal, misal: unbalance, misalignment, kerusakan pada gear atau bearing, dst. Salah satu kasus unbalance terjadi pada Centrifugal Fan di PT. PJB Services PLTU Amurang. Kasus unbalance pada Centrifugal Fan ini dapat direduksi dengan beberapa cara, salah satunya yaitu dengan penambahan Dynamic Vibration Absorber (DVA). Tugas akhir ini bertujuan untuk mereduksi getaran dengan penambahan DVA dan mengetahui pengaruh perubahan massa DVA terhadap respon getaran yang dihasilkan dari simulasi Simulink MATLAB.
Dengan mengangkat kasus tersebut, hal pertama yang dilakukan untuk mengetahui tipikal DVA yang cocok untuk kasus unbalance ini adalah mensimulasikan getaran yang terjadi ketika Centrifugal Fan dalam keadaan unbalance. Setelah diketahui karakteristik getarannya, dilakukan perancangan DVA teredam dengan variasi massa DVA. Jika massa DVA bervariasi, maka nilai stiffness dan damping DVA akan berubah pula nilainya. Setelah parameter dari DVA dihitung, rancangan DVA tersebut disimulasikan dalam keadaan sudah terpasang pada sistem Centrifugal Fan. Kemudian karaktersitik getaran dari hasil simulasi tersebut dibandingkan, saat sebelum dan sesudah pemasangan DVA. Seluruh parameter sistem Centrifugal Fan yang digunakan diperoleh dari PT. PJB Services PLTU Amurang. Dari data tersebut diperoleh nilai putaran kerja dari Centrifugal Fan sebesar 2840 rpm dan nilai vibrasi tertinggi arah horizontal (sumbu x) sebesar 48.52 mm/sec. Sedangkan untuk massa DVA dihitung dari massa system. Nilai stiffness dan damping DVA pada tiap massa berbeda, tergantung pada tiap rumus perhitungannya.
Dari hasil simulasi pemasangan DVA pada Centrifugal Fan didapatkan bahwa getaran yang terjadi pada system tidak berkurang, mulai dari massa pertama hingga massa kelima. Bahkan, saat massa DVA yang dipasang bertambah besar, getaran yang terjadi pada system juga semakin besar. Hal ini dimungkinkan getaran yang terjadi karena kondisi unbalance pada system Centrifugal Fan tersebut tidak dapat direduksi dengan pemasangan DVA. Hal ini juga bertentangan dengan teori dan perumusan bahwa reduksi yang dialami saat system telah dipasang DVA kurang lebih sebesar 90%.
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Sometimes there is a vibration inside a machine. This vibration caused by one thing and another, such as: unbalanced, misalignment, a damage on the gear or bearing and so on. The unbalanced case happened in Centrifugal Fan at PT. PJB Services PLTU Amurang. The unbalanced case in Centrifugal Fan can be reduced by several methods, one of them is by installing the Dynamic Vibration Absorber (DVA). This final assignment has a purpose to reduce the vibration by installing DVA and understanding the effect of DVA mass changes against vibration respond that is generated by simulation in Simulink MATLAB.
By lifting up this case, this final assignment is giving the solution to reduce the vibration which is caused by the unbalanced, by installing the DVA. The first thing to be done is to learn about the DVA type that matches for the unbalanced case and simulate the vibration when the Centrifugal Fan is unbalanced. After the vibration characteristic has been found, the next step is designing the damped DVA with the varied mass. If the DVA masses are varied, the stiffness and damping will change following the amount of the mass. After the parameter of the DVA has been calculated, the designs of the DVA are installed alternately on the Centrifugal Fan and simulate each of them. Then after the vibration characteristics as a result from the simulation have been collected, the vibration of the Centrifugal Fan will be compared on before and after the DVA installation. All of the parameters in the Centrifugal Fan system that is used in this final assignment was obtained from PT. PJB Services PLTU Amurang. In the data, there is a working frequency of the Centrifugal Fan by 2840 rpm and the highest vibration on horizontal direction (X axis) is 48.52 mm/sec. For the value of the DVA mass was calculated from the Centrifugal Fan system mass. The values of the stiffness and damping of the DVA on each mass are different, they depend on the calculations.
In the result of the installation of the DVA on Centrifugal Fan was acquired that the vibration inside the system can not be reduced, even with the first until the fifth DVA mass. Moreover, the bigger the DVA mass that was installed on the Centrifugal Fan, the vibration in the system will get larger than before. It is possible that this phenomena happens because the vibration itself can not be reduced by installing the DVA. This phenomena also contradicted with the theories and formulas based on trusted references that the amount of reduced vibration on the system will be about 90% after the DVA installation.
| Item Type: | Thesis (Undergraduate) |
|---|---|
| Uncontrolled Keywords: | Dynamic Vibration Absorber, Getaran, Unbalance, Centrifugal Fan |
| Subjects: | T Technology > TJ Mechanical engineering and machinery > TJ230 Machine design |
| Divisions: | Faculty of Industrial Technology > Mechanical Engineering > 21201-(S1) Undergraduate Thesis |
| Depositing User: | hilaliyah nur shabrina |
| Date Deposited: | 22 Nov 2017 02:21 |
| Last Modified: | 08 Mar 2019 03:25 |
| URI: | http://repository.its.ac.id/id/eprint/46001 |
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