Inspection of composite laminates in production line using Ultrasonic C-scan for NDT requires a competent and experience inspector in order to analyze the signal which involve various technical instruction. In this paper, two approaches had been used which are image based approach and signal based approach of ultrasonic C-Scan method for NDT of composite laminate are developed and applied, with the aim to compare and validate both techniques instead of surface defect percentage area. The idea is, to propose an image analysis technique which easy to handle by general worker either the defect percentage area between the image and signal analysis are acceptable range or not. Composite laminates 6 plies which produced in-house with geometry 280 mm length x 80 mm width x 2 mm thickness was drilled to consider as defect area. Then, further analysis was performed using image scanning and processing to calculate the percentage of the defect area before we proceeds to the ultrasonic signal based approach. This research had been successfully done with the maximum and the minimum yield percentage between image processing and ultrasonic signal based approach method are 17.12 percent and 8.52 percent.
Metallurgical bonded aluminium-copper bi-metal tube has a future prospect as an alternative material to copper in the heat, ventilation and air-conditioning (HVAC) industries. The application of aluminum-copper bi-metallic material is seems practical in maintaining the quality of existing products. However, the mechanical strength and fatigue properties of the bi-metal tubes are unknown. In this study, metallurgical, mechanical and fatigue properties of the copper phosphorous alloy and aluminium-copper bi-metal tubes were characterized through metallographic analysis, tensile, bending and fatigue tests. The results show that there observed a weak and brittle Al-Cu intermetallic compound at the interlayer between Al and Cu. Tensile fracture surface observation revealed that separation of Cu from Al occurred at the interlayer. The bending properties of the tubes were influenced by the amount of volume fraction of Cu in the materials. Three point bending fatigue test results showed that a critical buckling stress is presents for tubes with diameter less than 12.7mm. The aluminium-copper bi-metal tubes show degradation of fatigue strength almost 55% as compared to that of Cu alloy tube.
Aluminium recycling is now a well-known technique used in material manufacturing because it consumes less energy and is environmentally friendly. This paper presents the effect of burning temperature on rice husk silica as reinforcement of recycled Aluminium chip AA7075 on physical properties and hardness. Rice husk silica was prepared without any chemical treatments which are original rice husk (O), rice husk ash burned at 700°C (RHA) and calcination of rice husk ash burned at 1000°C (CRHA). Recycled Aluminium chip AA7075 reinforced with rice husk silica i.e., 2.5 wt.%, 5 wt.%, 7.5 wt.%, 10 wt.% and 12.5 wt.% were prepared. Analyses of silica were conducted by using x-ray diffraction (XRD) and x-ray fluorescence (XRF) test. Silica remains to be in amorphous phases for original rice husk and rice husk ash at 700°C. However, at a burning temperature of 1000°C, silica was observed in semi crystalline phase. Porosity and water absorption of composite of metal matrix increased with an increasing the composition of rice husk silica. The hardness of composite of metal matrix improved with increasing rice husk silica, while the hardness of chip AA7075/O and chip AA7075/CRHA decreased with increasing rice husk silica. Based on investigation to Aluminium reinforced rice husk at different burning temperatures, amorphous phase of silica burned at 700°C shows good potential to improve the hardness of material by appropriate composition of rice husk silica.
Stent implantation is an alternative invasive technique for treating the narrowed artery or stenosis in carotid artery to restore blood to the brain. However, the restenosis process is usually observed after a few weeks of carotid angioplasty and stenting due to abnormal progression of atherosclerosis and thrombosis. Many studies reported that the activity of atherosclerosis and thrombosis is majorly influenced by the geometrical strut configuration. Thus, this study was carried out to determine the hemodynamic performance on different geometrical stent strut configurations based on numerical modelling and statistical analyses. In this study, there are six stent types with different geometry that resembles the existing stent, namely as Type I, Type II, Type III, Type IV, Type V and Type VI which are resembling to Exponent (Medtronic), Precise (Cordis), Protégé (ev3), Vivexx Carotid Stent (C. R. Bard), Zilver Stent (Cook) and Acculink (Abbott Vascular), respectively. The stent strut configurations were 3-D modelled and simulated in different physiological conditions; normal blood pressure (NBP), pre-hypertension (PH) and hypertension stage one (HS1) through computational fluid dynamic (CFD) method. The hemodynamic performance of stent was analyzed based on parameters namely time averaged wall shear stress (TAWSS), time averaged wall shear stress gradient (TAWSSG), oscillatory shear index (OSI), relative residence time (RRT) and flow separation parameter (FSP). Meanwhile, Pictorial Selection Method was used to evaluate the best hemodynamic stent performance based on a scoring system. From observation, stent Type II was seen to show the highest score for TAWSS, which about 3.44 regardless of any physiological conditions. For TAWSSG, the lowest score was observed for Type V stent with 0.36. Furthermore, Type VI stent displayed the highest score for OSI while Type IV has the lowest score for FSP with 3.09 and 1.23, respectively. On the other hand, RRT was seen varying according to the physiological condition where the highest score in NBP condition was achieved by Type I while PH and HS1 condition was achieved by Type VI. In conclusion, Type VI has the best stent performance, whereas Type IV has the worst stent performance regarding the scoring system based on hemodynamic parameters. Further, Type I, Type II, Type III and Type V stents showed moderate hemodynamic performances for all physiological conditions.
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