PENGAMATAN MUAI PANJANG LOGAM ALUMUNIUM, BESI, DAN TEMBAGA MENGGUNAKAN MIKRO-RADIOGRAFI SINAR-X DIGITAL

A. MARIO YUDI PUTRANTO, Drs. Gede Bayu Suparta, M.S., Ph.D.

2014 | Skripsi | S1 FISIKA

Pada umumnya pengukuran muai panjang dilakukan menggunakan metode dilatometri mekanik, optikal interferometri, dan analisa termomekanikal. Namun metode-metode tersebut hanya dapat dilakukan pada keadaan laboratorium, dan menghasilkan nilai konstanta muai panjang yang menjadi acuan dalam dunia kerja. Dalam penelitian ini, dilakukan pengukuran muai panjang dan pembandingan koefisien muai panjang logam sampel melalui citra radiografi. Citra radiografi didapat menggunakan mikro-radiografi sinar-X yang dikembangkan oleh Grup Riset Fisika Citra FMIPA UGM. Citra yang didapat untuk setiap perubahan suhu logam diolah melalui software ImageJ. Pengolahan citra menggunakan proses penjumlahan (add), pengurangan (substract) dan menu stack serta analisa Adrian's FWHM dalam menentukan pergeseran tepi citra logam sampel. Penentuan koefisien muai panjang logam dilakukan melalui metode grafik dan penentuan gradien persamaan garis yang menggunakan metode kuadrat terkecil (least mean square). Pengukuran muai panjang logam menggunakan mikro-radiografi menunjukkan bahwa mikro-radiografi dapat digunakan dalam memeriksa muai panjang logam, karena mampu memberikan hasil pengukuran mendekati metode-metode yang telah umum dipakai. Pengukuran menggunakan mikro-radiografi dapat diaplikasikan dalam dunia kerja, karena mampu mengukur muai logam pada mesin dalam keadaan bekerja (online).

In general, the measurements of linear thermal expansion use the dilatometry mechanical techniques, optical interferometry, and thermomechanical analysis. However, these methods can only be done at lab situation, and produces value of coefficient of thermal expansion that be the reference in workplace. In this observation, the measurement of linear thermal expansion and the comparison of coefficient of thermal expansion of metal samples based on radiographic image have been done. Radiographic image is obtained using digital X-ray micro-radiograph that was developed by the Research Group of Physics Imaging FMIPA UGM. The image that was obtained for each metal temperature changes, is processed through ImageJ software. The processing of image use the addition, subtraction, stack and Adrian's FWHM analysis in determining the shift edge of the image samples. Determination of thermal expansion of metal is done through a graphic method and determining the gradient of line equation that uses the least mean square. The measurements of linear thermal expansion of metal using micro-radiography showed that the micro-radiograph can be used to check the measurements of linear thermal expansion of metal, because it can provide the result of the measurement approaching methods that have been commonly used. Measurements using a micro-radiography can be applied in workplace, because it ables to measure the expansion of metal on the working engine (online).

Kata Kunci : Muai panjang, mikro-radiografi digital, sinar-X, ImageJ