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Journal : Semesta Teknika

Pengaruh Fraksi Volume Serat terhadap Sifat-sifat Tarik Komposit Diperkuat Unidirectional Serat Tebu dengan Matrik Poliester Berli P. Kamiel, M. Budi Nur Rahman ,
Jurnal Semesta Teknika Vol 14, No 2 (2011): NOVEMBER 2011
Publisher : Jurnal Semesta Teknika

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Abstract

Sugar cane fiber has not optimallybeen used as reinforcement of compositematerial. So far, bagasse has been used as  firewood-substitute, raw material for papers, and brake lining. The purpose of this study is to investigate the effect of fiber volume fraction, Vf, on tensile strength of unidirectional sugar cane fiber/polyester composites. The material being used was sugar cane fiber, 268 SHCP BQTN  polyester resin and catalyst . Fibers were soaked in alkali (NaOH) 5% for 2 hours in order to remove their impurities. Composite panels were made with a printing press and the volume fractions of the fiber were 0%, 10%, 20%, 30% and 40%. Prior to being cut into specimens, the panels were subsequenlypost-cured at a temperature of 60 0C for 4 hours. Tensile testing wa carried out according to theASTM D638 standard, and fracture area photo macrographs of selected sampleswere analysed in order to find out the characteristics of fracture. It was found out that increasing the fiber volume fraction resulted in thedecrease of tesilestrength and strain,butincrease of the modulus of elasticity . The highest average tensile strength and strain was obtained at Vf = 0% (31.44 MPa and 9,11%), and a tensile modulus of elasticity was at Vf = 20% of 426.92 MPa. The observations on the photo macrographs showed thatcomposite fracture predominantly occuredspecimens withVf = 30%, and single fracture combined withfiber pull-out was identified for those ofVf = 0%, 10%, 20% and 40%.
Pengaruh Kecepatan Operasi Pompa Sentrifugal Terhadap Sensitifitas Metode Deteksi Fenomena Kavitasi Berbasis Parameter Statistik Domain Waktu Kamiel, Berli P; Ramadhan, Ray S
Semesta Teknika Vol 20, No 1 (2017): MEI 2017
Publisher : Semesta Teknika

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Abstract

Cavitation is one of the main concern on centrifugal pump faults that could cause component damages up to production failure in the industries. It is essential to detect and diagnose the fault as early as possible to prevent a catasthropic failure. Cavitation on sentrifugal pump could be caused by many factor, one of them are caused by the pump operating speed. This paper presents a method that able to detect cavitation by monitoring the vibrations level of the pump based on statistical analysis of time domain. This method is known as vibration monitoring technique that is undoubtedly the most effective technique to detect rotational machinery faults. The cavitation simulated on the test rig by varying the operating speed at 1000 RPM, 1200 RPM, 1400 RPM, …, 2600 RPM and by varying the size of suction valve opening. The cavitation phenomena are measured and indicated by magnitude of vibration level changes in stastical parameter such as Probability Density Function (PDF), Variance, Standard Deviation, Root Mean Square (RMS), Peak Value, Crest Factors and Kurtosis. The results show that PDF, Variance, Standard Deviation and RMS are proved to be able to detect cavitation caused by the pump operating speed variation. However, parameter such as Peak Value, Crest Factor and Kurtosis show low sensitivity and not suitable for the cavitation detection purposes.
Sifat-sifat Tarik dan Flexural Komposit Serat Sabut Kelapa Unidireksional/Poliester Sudarisman, Sudarisman; Kamiel, Berli P; Rahadi, Slamet
Semesta Teknika Vol 17, No 2 (2014): NOVEMBER 2014
Publisher : Semesta Teknika

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Abstract

The purpose of this study is to investigate the tensile and flexural properties of unidirectional coconut fiber/polyester composite materials, and to describe their failure modes. Specimens were cut from fiber/polyester composite plates containing various fiber contents. Materials being used in this study are coconut fiber that was previously alkali-treated and polyester resin matrix. Whilst tensile testing was carried out in accordance with the ASTM D3039 standard, flexural testing was based on the ASTM D790 standard. Failure surfaces of the representative specimens were then observed under an optical microscope, and their digital photo macrographs were captured for image analysis in order to describe their respective fiber distribution pattern and to determine their respective actual fiber volume fraction, Vf, by means of an open source software called ImageJ. It was found out that the actual Vf of the four composite plates being produced were 10.7%, 17.6%, 27.4% and 40.5%. It was revealed that while tensile strength increases with the increase of Vf, while failure strain, modulus elasticity and flexural strength decreases. The average highest tensile strength, tensile failure strain, and tensile modulus of elasticity were found being 30.01 MPa at Vf = 40.5%, 0.027 mm/mm at  = 0%, and 1.47 GPa at Vf = 0%, respectively. The average highest flexural strength, failure strain and modulus of elasticity were observed being 153.92 MPa at Vf = 10.7%, 0.0358 mm/mm at Vf = 0%, and 3.242 GPa at Vf =10.7%, respectively. It was observed that specimens were failed by fiber pull out and debonding.
Deteksi Cacat Bantalan Bola Pada Pompa Sentrifugal Menggunakan Spektrum Getaran Kamiel, Berli P; Mulyani, Mulyani; Sunardi, Sunardi
Semesta Teknika Vol 20, No 2 (2017): NOVEMBER 2017
Publisher : Semesta Teknika

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Abstract

One of the common fault in the centrifugal pump is faulty bearing. Bearings play a very important role for smooth rotation of a shaft. A bearing condition must be constantly monitored to ensure top performance of a pump. Therefore, a method is needed to detect an early defect in the bearings. One of the most widely used methods for bearing faults detection is based on the vibration analysis. Vibration analysis can detect a defect in a bearing without having to disassemble the machine. Furthermore, and it is fast and easy to be implemented. This study aims to develop a fault detection method on the ball bearing using spectrum analysis by applying envelope analysis. This research uses experimental method with three bearings conditions i.e. normal (no fault), outer race fault, and inner race fault. The type of ball bearings used are self aligning double row bearings. The vibration signal from each of bearing condition is taken from the centrifugal pump vibration test rig and measured using accelerometer sensor which is acquired directly with DAQ and then processed into Matlab. The analysis gives the result of frequency spectrum and envelope spectrum. This study concludes that the high amplitude on the frequency that coincide with the frequency of Ball Pass Frequency Outer Race (BPFO) and Ball Pass Frequency Inner Race (BPFI) make an indication of damage to the bearing on the outer and inner race respectively. The envelope spectrum gives better results as compared to the result of the frequency spectrum. This is because the high amplitude of low frequency generated from other components is blocked and removed using a high-pass filter. Consequently, it becomes easier to detect a low amplitude of high frequency vibration signal from a faulty bearing.
Deteksi Kavitasi Berbasis Getaran Pada Pompa Sentrifugal Menggunakan Principal Component Analysis (PCA) Kamiel, Berli Paripurna; Kausar, Ikhsan Aprima
Semesta Teknika Vol 21, No 2 (2018): NOVEMBER 2018
Publisher : Semesta Teknika

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.212219

Abstract

A centrifugal pump is one type of pumps that widely used in industries. Its mechanism which creates pressure changes may cause cavitation. Cavitation phenomenon that is not properly maintained may results fatal breakdown leading to high economic losses. Therefore, research is needed to find and develop a method that can detect early cavitation phenomena and identify it at several levels as well. This paper presents a method that can detect cavitation by monitoring the vibrations level of the pump based on statistical analysis of time domain and Principal Component Analysis (PCA). Vibration data is collected, trained and tested for each cavitation level. Training data is normalized and trained for each cavitation level using PCA which produces data loading matrix. The loading matrix is then multiplied by the testing data which gives a score matrix used to classify cavitation level of the centrifugal pump. The result shows that the method of domain-based PCA is successful in transforming the original data of 7 statistical parameters to 7 principal components (PC) with maximum variant. Three PCs gives 93.68% variants which can clearly identify and classify the differences between normal, early, intermediate and fully developed cavitation in the centrifugal pumps.
DETEKSI KAVITASI PADA POMPA SENTRIFUGAL MENGGUNAKAN SPEKTRUM GETARAN DAN SPEKTRUM ENVELOPE Kamiel, Berli P.; Nafsaka, Deby Arikh; Riyanta, Bambang; Asyratul, Azhim
Semesta Teknika Vol 22, No 1 (2019): MEI 2019
Publisher : Semesta Teknika

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.221231

Abstract

AbstrakKavitasi adalah salah satu indikator penting kondisi operasi sebuah pompa sentrifugal. Fenomena kavitasi ditunjukkan dengan terbentuknya formasi gelembung udara yang kemudian pecah secara tiba-tiba akibat perubahan tekanan pada sisi hisap pompa. Kavitasi dapat menyebabkan kerusakan yang parah komponen pompa terutama bagian sudu atau impeller. Kavitasi biasanya dapat diidentifikasi melalui suara bising dan timbulnya getaran yang berlebihan. Sebuah metode deteksi kavitasi dibutuhkan agar potensi kerusakan lebih lanjut pada pompa sentrifugal dapat diantisipasi secepatnya. Penelitian ini bertujuan menghasilkan sebuah metode deteksi kavitasi menggunakan spektrum getaran dan spektrum envelope pada bentang frekwensi rendah 0-4 kHz dan bentang frekwensi tinggi 4-8,5 kHz. Sinyal getaran pompa direkam menggunakan sebuah akselerometer yang diletakkan pada rumah volute pompa arah aksial. Sinyal getaran kemudian ditransformasikan kedalam spektrum dan spektrum envelope menggunakan  Fast Fourier Transform. Spektrum dan spektrum envelope untuk masing-masing bentang frekwensi dibandingkan antara pompa kondisi normal dan kondisi tiga level kavitasi kavitasi. Hasil penelitian menunjukkan bahwa spektrum frekwensi rendah dapat digunakan untuk mendeteksi kavitasi level 3 yang ditunjukkan dengan peningkatan amplitudo frekwensi poros sebesar 47,6 Hz dan ½ BPF sebesar 149,6 Hz. Sedangkan kavitasi level 1 dapat dideteksi oleh spektrum envelope pada bentang frekwensi tinggi. Dapat disimpulkan pula bahwa penurunan ampitudo teramati secara umum pada domain waktu seiring dengan meningkatnya level kavitasi. AbstractCavitation is an important indication of operation condition for a centrifugal pump. An indication of the appearance of cavitation is the formation of bubbles which collapse suddenly when the pressure changed on the suction side of the pump. The formation of cavitation bubbles can cause fault to the inner pump components. The fault that often results from cavitation phenomenon is affected in the impeller. This fault is usully identified through noise and vibration generated. Therefore, a method is needed to detect early cavitation phenomenon at the centrifugal pump. This study aims to develop cavitation detection methods using the vibration spectrum and envelope spectrum of low frequency band of 0-4 kHz and high frequency band of 4 kHz-8,5 kHz. In this study, cavitation detection in conducted by recording vibration signals that occur at centrifugal pump using an accelerometer. The data obtained is then transformed into the frequency domain and envelope spectrum using Fast Fourier Transform. The results were compared between normal condition and level 1, 2, and 3 cavitation. Comparisons were made on each vibration spectrum and envelope spectrum at the low frequency and high frequency bands. The result of this study showed that the vibration spectrum with low frequency band can detect the formation of level 3 cavitation with an increase in shaft frequency amplitude (47,26 Hz) and ½ BPF (149,6 Hz). Whereas early cavitation or level 1 cavitation was identified through the envelope spectrum at high frequency band. It also showed that a decrease in amplitude occured gradually in the time domain along with increasing level of cavitation.
KLASIFIKASI CACAT LINTASAN DALAM BANTALAN BOLA BERBASIS SUPPORT VECTOR MACHINE (SVM) PADA FAN INDUSTRI Kamiel, Berli Paripurna; Wiranto, Arie Joko; Riyanta, Bambang; Yulianto, Sulis
Semesta Teknika Vol 22, No 2 (2019): NOVEMBER 2019
Publisher : Semesta Teknika

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Abstract

Fan adalah sebuah mesin industri yang berfungsi  mensirkulasikan udara di dalam sebuah ruangan. Salah satu komponen dari fan yang sering rusak adalah bantalan. Metode spektrum merupakan salah satu metode deteksi rusak/cacat bantalan berbasis getaran yang umum digunakan namun grafik spektrum sering sulit dipahami oleh operator di lapangan. Metode pengenalan pola (pattern recognition) adalah metode yang mudah digunakan karena tidak perlu menterjemahkan grafik spektrum. Metode pengenalan pola yang digunakan pada penelitian ini adalah Support Vector Machine (SVM). Tujuan penelitian ini adalah mendeteksi cacat lintasan dalam pada bantalan bola. Penelitian ini menggunakan dua kondisi bantalan yang berbeda yaitu bantalan normal, dan bantalan cacat. Cacat pada bantalan dibuat dengan metode Electrical Discharge Machine (EDM) pada lintasan dalam dengan kedalaman 1,4 mm dan lebar 0,4 mm. Sinyal getaran bantalan direkam dari rig uji fan industri menggunakan software MATLAB dengan merekam data sebanyak 700 file untuk setiap kondisi. Data tersebut diektraksi kedalam 17 parameter statistik yang kemudian diseleksi secara visual sebagai input SVM. Klasifikasi SVM dilakukan dengan variasi kernel Radial Basis Function (RBF), Polynomial dan Linear. Hasil penelitian menunjukkan parameter statistik entropy dengan standart error menggunakan variasi kernel Radial Basis Function (RBF), Polynomial dan Linear adalah rekomendasi untuk klasifikasi cacat pada bantalan lintasan dalam karena menghasilkan akurasi sebesar 100%. Industrial fan is one of -rotating machinery commonly used by industries to circulate air in a particular area. One of the most important component of a fan is the bearing which may fault during its operation Spectrum analysis  is one of vibration-based methods frequently used to detect faulty bearing  but this method has a disadvantage that is not easily understood by operators in the field. Pattern recognition method  is an easy method to be used because it does not need to interpret the spectrum. The pattern recognition method used in this study is Support Vector Machine (SVM). The purpose of this study is to detect inner race fault of a ball bearing using SVM. This study uses two different bearings, namely a normal bearing and a faulty bearing. Fault on the bearing were made by Electrical Discharge Machine (EDM) on the inner race with a width of 0.4 mm  and a depth of 1.4 mm. The test is carried out on an industrial fan test rig and recorded using MATLAB. The vibration signal is recorded to result of 700 files for each bearing condition. The vibration data is subsequently extracted into 17 statistical parameters which are then visually selected as input of SVM classifier. The SVM classifiear is trained using variations of the Radial Basis Function (RBF), Polynomial and Linear kernels. The results shows that the statistical parameters of entropy-standard error using variation of the RBF, Polynomial and Linear kernels gives the highest accuracy of 100%.
Deteksi Cacat Lintasan Luar Bantalan Bola pada Fan Industri Menggunakan Metode Cepstrum Kamiel, Berli Paripurna
Semesta Teknika Vol 23, No 1 (2020): MEI 2020
Publisher : Semesta Teknika

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Abstract

Bantalan bola pada sebuah fan (kipas) menerima beban dinamis yang sangat besar ketika beroperasi. Hal ini menyebabkan bantalan mengalami keausan yang harus dapat segera dideteksi untuk mencegah kerusakan/cacat lebih lanjut. Salah satu metode deteksi yang sering digunakan adalah metode analisis spektrum. Namun metode ini menghasilkan harmonik dan sidebands yang rumit jika diaplikasikan pada fan dengan transmisi roda gigi sehingga observasi amplitudo pada spektrum sulit dilakukan. Penelitian ini mengusulkan metode cepstrum ketimbang spektrum karena cepstrum dapat mengelompokkan berbagai harmonik yang berasal dari getaran komponen-komponen fan sehingga amplitudo cacat bantalan dapat diidentifikasi dengan mudah dan jelas. Bantalan yang digunakan dalam penelitian adalah tipe ASB 6209 2RS dengan kondisi normal (tanpa cacat) dan cacat lintasan luar. Cacat pada bantalan sengaja dibuat menggunakan Electrical Discharge Machine (EDM)  dengan kawat kuningan berdiameter 0,25 mm. Hasil penelitian menunjukkan bahwa spektrum dapat mendeteksi frekuensi poros fan  9,11 Hz, frekuensi ball pass frequency outer (BPFO) 36,52 Hz, dan frekuensi poros roda gigi 22,59 Hz.  Namun demikian amplitudo BPFO sulit diidentifikasi pada spektrum karena secara visual bercampur dengan amplitudo harmonik dari komponen-komponen lain yang turut bergetar pada fan. Hasil lebih baik diberikan oleh metode cepstrum dimana amplitudo quefrency BPFO sebesar 0,027 detik, yang bersesuaian dengan BPFO, sangat jelas terlihat karena tidak terganggu oleh amplitudo lain di sekitarnya. A Ball bearing in a fan  experience a very large dynamic load during its operation. This causes wear which must be detected immediately to prevent severe damage. One detection method that is often used is the spectrum analysis. However, this method produces complex harmonics and sidebands when applied to a fan with a gear transmission which makes it difficult to observe amplitude on the spectrum. This research proposes the cepstrum method rather than the spectrum because the cepstrum can classify the various harmonics that come from the vibrations of the fan components so that the amplitude of the bearing defects can be identified easily and clearly. The bearings used in the study are ASB 6209 2RS with normal condition (no fault) and with outer race fault. Defect in the bearings is intentionally made using an Electrical Discharge Machine (EDM) with 0,25 mm brass wire. The results show that the spectrum can detect the fan shaft frequency of 9,11 Hz, the ball pass frequency outer race (BPFO) 36,52 Hz, and the gear shaft frequency of 22,59 Hz. However, the BPFO amplitude is difficult to identify on the spectrum because it is visually mixed with the harmonic amplitude of the other vibrating components. A prominent results are given by the cepstrum method where the quefrency of 0,027 s, which corresponds to the BPFO, is clearly visible because it is not disturbed by other amplitudes. 
Deteksi Kavitasi Berbasis Getaran Pada Pompa Sentrifugal Menggunakan Principal Component Analysis (PCA) Kamiel, Berli Paripurna; Kausar, Ikhsan Aprima
Semesta Teknika Vol 21, No 2 (2018): NOVEMBER 2018
Publisher : Universitas Muhammadiyah Yogyakarta

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.18196/st.212219

Abstract

A centrifugal pump is one type of pumps that widely used in industries. Its mechanism which creates pressure changes may cause cavitation. Cavitation phenomenon that is not properly maintained may results fatal breakdown leading to high economic losses. Therefore, research is needed to find and develop a method that can detect early cavitation phenomena and identify it at several levels as well. This paper presents a method that can detect cavitation by monitoring the vibrations level of the pump based on statistical analysis of time domain and Principal Component Analysis (PCA). Vibration data is collected, trained and tested for each cavitation level. Training data is normalized and trained for each cavitation level using PCA which produces data loading matrix. The loading matrix is then multiplied by the testing data which gives a score matrix used to classify cavitation level of the centrifugal pump. The result shows that the method of domain-based PCA is successful in transforming the original data of 7 statistical parameters to 7 principal components (PC) with maximum variant. Three PCs gives 93.68% variants which can clearly identify and classify the differences between normal, early, intermediate and fully developed cavitation in the centrifugal pumps.