Failure prediction of cracked pressure vessel is analyzed based on crack growth behavior under fatigue loading. The major objective of this study was to investigate and validate the use of commonly used industry standard with finite element method in order to predict failure of cracked pressure vessel. Growing of crack due to fatigue load was analyzed using both analytical and finite element method. In analytical side, API 579 Code is used with involving safety and correction factor which will increase conservatism degree of the results. Pressure vessel with D/t ratio 40, 60, and 80 were taken into analysis. Semi elliptical cracks in longitudinal and circumferential position were included into analysis with ratio a/t=0.3, 0.5, 0.8 and a/c=0.15, 0.125, 0.1. In this paper, there are 84 numerical model were solved numerically and plotted into several curves. Comparisons between API 579 and finite element simulation show that pressure vessel with D/t=40, 60 and 80 have percent error about 2.16 %, 9.32 % and 10.57 %, respectively. This results are reasonable due to several safety factor are included in API 579 analysis. Results of this paper can be used as consideration for make a decision regarding to integrity analysis of pressure vessel.
Mechanical Engineering, Universitas Riau, Indonesia.
Hydroxyapatite is one of important material in orthopedic application because its features like human bone, and it has potential to replace metal and ceramic in implantation. Hydroxyapatite may get from waste which rich calcium like sea shell and snail shell. In this research, the characterization of raw materials of hydroxyapatite from freshwater snailshell (Sulcospira sp.) was investigated. The shell was milled with ball mill in 200 rpm during 15 minute with 4 steps. Between the milling was conducted heat treatment process at temperature 9000C for 4h. The shell powder was then sorted based on its roughness with siever machine. Powder characterization was done with Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) and X-ray Diffraction (XRD). Result of this study show that the minimum size of powder about 67 µm and percentage of calcium in the powder is increased until 55%.
Biomedical Department, Medicine Faculty, Andalas University, West Sumatera, Indonesia
Mechanical Engineering, Engineering Faculty, Andalas University, West Sumatera, Indonesia
Hydroxyapatite is one of important material in orthopedic application because its features like human bone, and it has potential to replace metal and ceramic in implantation. Hydroxyapatite may get from waste which rich calcium like sea shell and snail shell. In this research, the characterization of raw materials of hydroxyapatite from freshwater snailshell (Sulcospira sp.) was investigated. The shell was milled with ball mill in 200 rpm during 15 minute with 4 steps. Between the milling was conducted heat treatment process at temperature 9000C for 4h. The shell powder was then sorted based on its roughness with siever machine. Powder characterization was done with Scanning Electron Microscope (SEM), Energy Dispersive X-ray (EDX) and X-ray Diffraction (XRD). Result of this study show that the minimum size of powder about 67 µm and percentage of calcium in the powder is increased until 55%.
Electrical Engineering Department, Sekolah Tinggi Teknologi Pekanbaru (STTP), Indonesia