Particle reinforced metal matrix composites are skilled to fulfill the late needs of cutting edge designing applications, because of its tunable mechanical properties. Stir casting is one of the unmistakable and affordable strategies for preparing of particle reinforced metal matrix composites. However, complete investigation and evaluation of the vortex pressure and the homogenous distribution of particles are still an obstacle for the research community. In this method, vortex pressure and flow pattern are the important factors for the dispersion of particles in the liquid metal. Effectual flow pattern and vortex pressure can be attained by optimizing stir casting parameters such as volume concentration (5%, 10%), stirrer blade angle (45º, 90º), impeller position (20%, 40%) from the base, viscosity of Al melt (1.04 mPa-s, 1.24 mPa-s) and holding time (10 minutes, 15 minutes). In this research, computational fluid dynamics has been used to find the vortex pressure, which influences the particle distribution. A new photographic technique was implemented to find out the flow pattern of the reinforcement particles and the stir casting parameters are optimized using Taguchi method. Optimized parameters have been utilized for the production of PRMMCs. In addition, micro structural image and hardness test confirm the uniform particle distribution of the reinforcement particles. From the outcome of various experimentations, 10 minutes holding time of the stirrer blade with 45ᴼ angle which was kept 40% from the base and the viscosity of the Al melt (1.04mPa-s) with 10% volume fraction of SiC particles shows effective flow pattern and optimum vortex pressure with homogenous distribution of SiC particles.
Additive manufacturing plays a major role in medical science. One of the applications is the development of bone scaffolds. During scaffold fabrication, obtaining the properties of the polyamide scaffolds to mimic the elastic properties of human subchondral bone is a challenging task. In order to overcome this challenge, the present numerical study validated by experimental routine allows optimizing, fabricating and automating the generation of open-porous polyamide scaffolds. Human subchondral bone has an elastic modulus of 1.15 GPa and pore size of 800 μm which helps for cell in-growth. The design parameters such as strut diameter (0.6 to 3mm) and unit cell size (1.4 to 5 mm) were considered for this investigation. The optimized scaffold structure was fabricated using selective laser sintering method, one of the Additive Manufacturing (AM) processes and the structure was validated through uniaxial compression. Experimental test revealed a deviation in structural modulus of about 14 %, 10 % and 17 % for circular, square and hexagonal cross-section respectively. Optimized unit cell dimensions were found. The preliminary MTT (Methyl Thiazolyl diphenyl-Tetrazolium bromide) assay tests to evaluate the distributions of cells were performed, using in-vitro perfusion culture experiments. It was found that the scaffold structure with square cross section has the maximum percentage of cell viability of 58.33%. A Computer-Aided Design tool was developed using CATIA V5 Visual Basic program for modelling the bone scaffolds with better interconnectivity of unit blocks, porosity and compressive strength. This program facilitates automatic generation of optimized scaffold structure by providing necessary input parameters. The developed CAD tool was efficient enough to model the customized scaffold.
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