1,721,116 research outputs found
Modified Design of Pin-on-Ring Tribometer for Hip Joint Prostheses Measurement; Case Study on Salat Activity_Peer Review
Full text link, Jamari Jamari, Sulardjaka Sulardjaka, Mohamad Tauviqirrahman, Emile van der Heid
PERHITUNGAN KEAUSAN PIN PADA SISTEM KONTAK SLIDING PIN-ON-DISC MENGGUNAKAN METODE ANALITIK DAN METODE ELEMEN HINGGA
Full text linkWear is one of the phenomena which plays important role in the life time designing of the mechanical component. Wear, in engineering design, should be considered due to its relation in material loss. The better engineering design of the mechanical component will reduce wear, results the lower energy loss, and prolong the component life time. There are three types of wear: mechanical, chemical and thermal. Sliding contact system in tribometer, i.e. pin-on-disc test, is one of the examples of the mechanical wear. Pin-on-disc is one of the most popular tribometer to conduct an experiment in wear prediction but this experimental research requires a large number of experiments, time and costs. Therefore, finite element and analytical solution should be the more commonly used approach to predict the wear behavior of a pair of materials.
The prediction of wear by analytical solution approach has been used by Archard, Sarkar and GIWM (Global incremental wear model) by Hegadekatte, while finite element approach has been studied by Podra for 2D analysis and Hegadekatte for 3D analysis. This research reports the comparison between the analytical and finite element approach in predicting wear. The results show that there is 15.36% deviation between GIWM developed by Hegadekatte and present GIWM developed by the author, 2.69% deviation between FEM developed by Hegadekatte and present FEM developed by the author and 6.58% between present GIWM developed by the author and present FEM developed by the author.
Keywords: wear modeling, pin on disc, analytical model, finite elemen
Lubricated MEMS: effect of boundary slippage and texturing
Full text linkMany types of micro-electro-mechanical-system (MEMS) based products are currently employed in a variety of applications. Recently, there has been an increase in the demand for higher reliability of MEMS which incorporate moving parts for each intended application. This is because the reliability of MEMS containing moving parts is poor and has a limited lifetime. Applying a lubricant to these systems to avoid wear hampers the movement due to the adhesive/surface forces, leading to stiction. By modifying the contacting surfaces, one is able to enhance the behavior of surfaces in a controlled way and thus alter the flow pattern in the liquid lubricating film for an enhanced performance. In this thesis, the concept of complex slip surface (CSS) as an artificial (deterministic) boundary slip surface is introduced. The thesis examines the exploitation of the artificial boundary slip to improve the performance of liquid lubricated-MEMS, with the emphasis on increasing the load support and reducing the coefficient of friction. Therefore, it is of great importance to get a clear view of the concept of the artificial boundary slip with respect to the performance of lubricated-MEMS
Study of Sliding Contact of Layered Surfaces
Full text linkTribology, one of the applied sciences in mechanical engineering which studies friction, wear and lubrication, contributes in the effort of minimizing wear and loses due to contact between two surfaces. Tribology is an essential technology for most of industries due to the impacts on energy efficiency, machine life, engine design, maintenance schedules and machine downtime. In the medical area, tribology is also critical to the long term mobility, healthy and the quality of life of patients with for instance replacement joints. An energy efficiency which is related to green technology is an important issue nowadays. However, it appears that possibilities to save energy by reducing the losses due to wear and friction have not sufficiently been taken into account in a large number of countries, especially in the developed-countries. It can be said that through tribology strategies for energy conservation can be reached. Industry could savings 1.5 % of GNP for the UK from better tribology application, based on the report made by Jost in 1966. It was a surprising value at that time. The number can be larger at this moment after considering the increasing of the use of the components in mechanical systems. A value at the same level is expected for Indonesia if the better tribology technology is applied.
Running-in, as a part of the tribology science, has a significant role in the reliability of mechanical components. Running-in occurs in the first period in the life-time of a rolling or sliding contact of a lubricated system. The running-in phase cannot be avoided in any mechanical system in which moving parts are present. For this, the running-in behaviour of surfaces has to be understood to be able to give guidelines to industry how to produce in a simple way their surfaces.
The long term project in the Laboratory for Engineering Design and Tribology, Department of Mechanical Engineering UNDIP focuses on the research of running-in of rolling-sliding contact system. Study of the layered surface becomes important related to the running-in because the layered surface contributes specific surface roughness. The specific surface roughness controls the running-in process.
One of the effective ways to improve the tribological properties of the contacting surface during running-in is by laminating or coating the surface with thin layers. The layers which can be deposited from several nano to a few microns are designed to control the surface roughness. The appropriate initial surface roughness, produced by good design of the thin layers, can contribute in reducing the friction and the wear rate in the running-in process and, as a result, prolong the component life.
It is important to realize that the mechanical contact between solids is localized to micro-scale contact spots that together form the real contact area. The contact pressure in these tiny areas is of the order of their hardness irrespective of the nominal contact pressure. Bearing this in mind, it is not surprising that damage can occur even in apparently very mildly loaded tribological contacts. One such example is the damage occurring on ceramic seals in sliding contact despite the nominal contact pressure being a hundred thousand times lower than their hardness. A layered surface can fail prematurely due to the detachment, delamination, cracking and/or spalling of the coating material. The present research will obtain the situation where the coating/layer, the substrate and the interface show a good performance during the sliding contact.
The conventional way to determine the layered surface behaviour is by performing experiments. The different material pair of the thin layer/film, coefficient of friction and load will show a different state of the stress distribution, the contact pressure, and the wear. The experimental research on layered surface requires a large number of experiments and the costs are enormous. Due to the difficulty in making precise measurements and the lack of the measurement setup in Indonesia, numerical method is the best approach to study the behaviour of the layered surface contact system. Therefore, in this project, finite element analysis (FEA), as one of the useful numerical tools, will be used to solve the problem in the present study.
Different arrangement of the thin film, i.e. layer/film thickness and the structure of the layer, will be used as the variable in the sliding contact simulation. The commercial finite element software package ANSYS is used for the simulation. Several geometrical models will be used for the simulation based on the previous results from the research conducted in the Laboratory for Engineering Design and Tribology UNDIP. Variations of load, below and beyond the critical load, are applied to the contacting layered bodies. The critical stress distribution, strain, contact pressure, and deformation due to sliding contact on the layer, the substrate and the interface will be reported. Finally, the optimum model for the layered surface is presented where stresses, pressure and strain is satisfactory in preventing damage of the layer due to sliding action
STUDI PENERAPAN KETERAMPILAN MENGAJAR AL-QUR€™AN HADITS DI MADRASAH ALIYAH AL-IKHLAS PAMONA SELATAN KABUPATEN POSO
Full text linkEffect of inertia on the cavitation phenomena of hydrodynamic textured bearings considering slip (lembar review)
Full text linkPengujian Bearing Pompa Sentrifugal untuk Nelayan Produk Industri Kecil dan Menengah
Full text linkPompa air untuk kapal nelayan adalah salah satu jenis pompa sentrifugal yang digunakan sebagai alat pendukung kapal nelayan dalam melaut. Pompa sentrifugal ini berfungsi untuk mengeluarkan air laut yang masuk ke kapal akibat proses menarik jaring, ombak yang masuk ke kapal dan kebocoran minor pada kapal. Pada kenyataan di lapangan, pompa kapal nelayan produk IKM memerlukan perbaikan/penggantian pompa setiap 2-3 bulan sekali sedang produk impor mampu bertahan 1-2 tahun masa pakai tanpa masalah. Peneltian ini bertujuan untuk mencari penyebab kerusakan yang terjadi pada pompa produk IKM dengan melakukan pengujian pompa yang menyerupai kinerja pompa di kapal nelayan saat berlayar. Analisa difokuskan pada komponen sistem bearing: inner raceway dan ball bearing menggunakan pengamatan mikroskop dan SEM. Pompa kapal yang diuji berjumlah 3 buah: 2 buah pompa produk IKM dan 1 buah pompa produk impor. Hasilnya pada hari ke-21 pengujian salah satu pompa produk IKM mengalami kemacetan dan berhenti beroperasi sementara dua pompa lain masih berfungsi. Analisa yang dilakukan terhadap inner raceway dan ball bearing menunjukkan adanya flaking pada kedua permukaan komponen bearing tersebut. Penyebab flaking pada awal siklus penggunaan bearing pada pompa kapal IKM ini adalah akibat kurangnya pelumas saat bearing berputar akibat bocornya pelumas. Seal yang seharusnya menahan pelumas untuk tetap berada di bejana tidak berfungsi baik sehingga pelumas mengalami kebocoran, menjadikan gesekan berlebih pada bearing dan mengakibatkan flaking. Langkah perbaikan yang perlu diambil oleh IKM adalah memperbaiki kualitas perencanaan seal pelumas pada pompa kapal produk IKM. Pelumasan yang berfungsi baik sangat vital terhadap kinerja bearing dan memperpanjang umur pakai bearing
LAPORAN INDIVIDU PRAKTIK PENGALAMAN LAPANGAN SMK NEGERI 1 PENGASIH
Full text linkUniversitasNegeriYogyakarta memiliki sebuah program yang ditujukan bagi mahasiswa yang mengambil jurusan kependidikan yaitu program praktik pengalaman Lapangan (PPL). Salah satu misiyang dimiliki UNY yaitu menyiapkantenagakependidikan yang memilikisikap, pengetahuan, danketerampilansebagaitenagaprofesional. Untuk menyiapkan tenaga kependidikan tersebut UNY memberikan pengetahuan dan keterampilan menjadi tenaga pendidik.Program PPL merupakan program yang harus ditempuh oleh mahasiswa karena menjadi salah satu syarat untuk menempuh gelar sarjana kependidikan selain tugas akhir. Program ini dilaksanakan oleh mahasiswa dengan diawali dengan observasi ke lapangan, sehingga mengetahui kondisi yang ada di sekolah khususnya di SMK N 1 Pengasih, Kulon Progo. Setelah mengetahui keadaan sekolah berdasarkan data yang telah terkumpul, disusunlah program kerja yang dapat menjadi pedoman dalam melaksanakan PPL berdasarkan skala prioritas, kebutuhan, dan waktu.
Praktik mengajar dilakukan untuk melatih ketrampilan dan kemampuan mahasiswa dalam mengajar, berdasarkan bekal dan persiapan yang telah dilakukan. Pelaksanaan program PPL berlangsung berdasarkan rencana yang telah dibuat dan menerapkan ilmu berdasarkan pembelajaran mikro. Pada kegiatan PPL, mahasiswa menerapkan langkah-langkah dalam mengajar dan berdasarkan prinsip-prinsip pembelajaran. Kegiatan PPL di SMK Negeri 1 Pengasih dilaksanakan pada tanggal 11 sampai dengan 15 Juli 2016 dan 26 Agustus 2016 sampai dengan 16 September 2016. Mahasiswa praktik mengajar 3 kelas yaitu kelas XII Multi Media (Selasajam ke 1,2 dan 3) kelas XII Pemasaran (Rabu Jam ke 1,2 dan 3) kelas XII Akutansi (kamis jam ke 1,2 dan 3) Saya Mengajar Olahraga Tujuannya Adalah Untuk Meningkatkan Kebugaran Jasmani Siswa.
Praktik Pengalaman Lapangan (PPL) merupakan sarana yang paling tepat bagi mahasiswa jurusan kependidikan untuk bisa mengaplikasikan ilmu yang diperoleh dibangku perkuliahan ke sekolah. PPL yang mempunyai kegiatan yang terkait dengan proses pembelajaran maupun kegiatan yang mendukung berlangsungnya pembelajaran dapat memberikan pengalaman belajar bagi mahasiswa terutama dalam hal pengalaman mengajar, memperluas wawasan, pelatihan dan pengembangan kompetensi yang diperlukan dalam pembelajaran, peningkatan keterampilan, kemandirian, tanggung jawab, dan kemampuan dalam memecahkan masalah
FAKTOR-FAKTOR YANG MEMPENGARUHI KEPUASAN KONSUMEN KHUSUSNYA SISWA SMA ATAU SMK DIY DALAMMENGGUNAKAN LAYANAN KOLAM RENANG UNY
Full text linkKolam renang FIK UNY banyak diminati oleh para pengunjung terutama
anak sekolah. Untuk mengetahui kepuasan konsumen dalam mengunakan layanan
kolam renang dalamPenelitian ini bertujuan untuk mengetahui faktor-faktor yang
mempengaruhi kepuasan konsumen khususnya siswa SMA/SMK DIY dalam
menggunakan layanan kolam renang UNY.
Penelitian ini adalah penelitian deskriptif kuantitatif dengan menggunakan
metode survei. Instrumen yang digunakan adalah angket (kuesioner) dengan
validitas 0,441 dan reliabilitas 0,956,yang telahdiuji coba kepada responden
sebanyak 15 anak,dalamSubjek penelitian ini adalah siswa SMA/SMK DIY yang
menggunakan layanan kolam renang UNY sebanyak 55 anak. Teknik analisis data
yang digunakan dalam peneitian ini adalah deskriptif dengan presentase.
Berdasarkan hasil penelitian dan pembahasan diketahui kepuasan konsumen
khususnya siswa SMA Atau SMK DIY dalam menggunakan layanan kolam
renang UNY dalam bentuk bentuk diagram lingkaran sebagian besarpada kategori
keandalan sebesar 19,95 %, ketanggapan 20,01 %, keyakinan 20,29 %, empati
19,61%, berwujud 20,14 %, dan pada kategori baik dengan persentase sebesar
36,36 %, pada ketegori cukup baik sebesar 29,09 %, pada kategori kurang sebesar
27,27 %, pada kategori sangat sangat kurang sebesar 5,45 % dan kategori sangat
baik sebesar 1,81 %
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