Present study, two-dimensional numerical solution for the same test condition has been performed by employing the turbulent model of RNG-k-ε to simulate the flow pattern after a rectangular bluff body of which has height to width ratio of two in various wavy surface conditions and Reynolds numbers. Sinusoidal surfaces were chosen for wavy condition to represent the wavy boundary. Range of Reynolds numbers were 1480 to 3300 and the waves amplitude were 0.13 of the bluff body height (0.13D), 0.33D and 0.67D. Comparisons were made against flow over the flat surface for the same flow condition. For most cases studied, two vortices always present in the region in the vicinity close to the bluff body. Larger size of vortices appears in the middle area than those in the upper area of the flow and less vortices occurs in the lower area. For low amplitude wave, the flow tends to follow the wave and resulted in large streamwise and spanwise negative velocity zone behind the bluff body. As the wave amplitude increases, the size of this negative velocity region will reduce. Otherwise.all wavy surface condition with the variation of amplitude also increases the strength of vortices as the Reynolds number increases occurred in the middle area to provide with the velocity profile along centerline. In general, the numerical solutions were in good result to calculate the velocity pattern.
Department of Mechanical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia
Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai Johor Bahru, Malaysia
The stainless steel 316L has been successfully coated by hydroxyapatite (HA) for increased their biocompatibility. The purposes of this research are to investigate the effect of applied voltage and deposition time on the properties of HA coatings. Stainless steel 316L with size of 20x20x1 mm3 put into alcohol and water solution for 1 hour. HA solution was prepared in ethanol solution used magnetic stirrer for 2 hours and 200 rpm. Subsequently the HA powder was deposited by electrophoretic deposition (EPD) using carbon as anode at 40, 60 and 80 volt and deposition time 2, 7, 12 and 17 minutes. It was observed from SEM analysis that HA deposited on stainless steel increased with higher voltage, thickness of HA layer on stainless steel was 30, 45 and 55 µm for deposition 17 minutes and applied voltage 40, 60 and 80 volt. Thickness of HA layer on substrate increased,as the time deposition increased with result 30, 35, 50 and 55 µm at deposition 80 volt and deposition time 2, 7, 12 and 17 minutes. The intensity of HA peaks in the coated substrate was highest at 80 volt and deposition 17 minutes. HA coatings at applied voltage 80 volt and deposition time 17 minutes was obtained suitable for bone plate.
Department of Chemical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia
Accuracy is the closeness value of a measurement results to the actual value. In reality, it is impossible to gain a 100% presice value same as the actual value of measurement. Therefore that accuracy cannot be perfect, in designs they often specify tolerances that is, acceptable variations in precision. Instead of giving one precise value, a tolerance specifies a range of acceptable result, and allowed amount of variation. This is often given as a deviation (difference) of that from an absolute accurate value. Using a high accuracy measurement device will produce accurate measurement data set and other wise it will not meet desired standards of measurement value. This research aims to determine the value of the mandrel roundness deviation, roundness accuracy according to “Roundness Tester Machine (RTM)” data reading. As mandrel is a reference measured object, so the reading of that of the RTM will tell how good the RTM be considered as a roundness tester instrument. Deviation was determined based upon radius average value of mandrel rod circumscribed circle. The longest and the shortest radius of that are called outer circle radius and the inner circle radius consecutively. They are recognized as the outer deviation and inner deviation of the roundness. It is reported based on series measurement, that the accuracy value of roundness measuring instrument RTM for ten positions along the mandrel rod are as follows: in position 1 = 0,006 mm, position 2 = 0,006 mm, position 3 = 0,011 mm, position 4 = 0,018 mm, position 5 = 0,003 mm, position 6 = 0,018 mm, position 7 = 0,021 mm, position 8 = 0,031 mm, position 9 = 0,002 mm, position 10 = 0,001 mm. In percentage, error measuring instrument (instrument error) that the maximum error is 0,02944 mm or 18,871% and the minimum deviation is 0,00029 mm or 0,225%. Operator error or measuring (Human Error) for first test (human) 22%, second test 5,33%, third test 182%, fourth test 187%, fifth test 58%.
Department of Mechanical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia
In this paper, a parametric study will be conducted on Bouguet’s camera calibration method. The main disadvantages of the method include too many checkerboard image sampling and a lot of clicking of chessboard pattern image. Four checkerboards that have same outer dimension but different size in small squares will be used as tools to determine minimum sampling amount of checkerboard’s image and the best suitable checkerboard for the particular measurement system. A DSLR Canon 7D camera with 50mm fixed lens is used as a sensor. Focal length as one of parameters resulted from calibration process for each checkerboard is then compared with lens’s focal length. Finally, the calibration process is applied for structural in-plane deflection measurement. A simple beam rig is used as a structural model. Repeatability and accuracy of the measurement is also to be analyzed.The results show that the minimum number of image sampling for good result is 12 times and 12x12 square checkerboard is the best for particular measurement system. Accuracy of the measurement using 12x12checkerboard with 12 times image sampling is around 4.5%.
Faculty of Mechanical and Aerospace Engineering, Institute of Technology Bandung, Bandung, Indonesia