Showing 5 results for Response Surface Methodology
N. Radhika, R. Raghu,
Volume 13, Issue 4 (12-2016)
Abstract
Functionally graded aluminium/zirconia metal matrix composite was fabricated using stir casting technique followed by horizontal centrifugal casting process and a hollow cylindrical functionally graded composite (150 x 150 x 16 mm) was obtained with centrifuging speed of 1200 rpm. The microstructural evaluation and hardness test was carried out on the outer and inner surface of the functionally graded composite at a distance of 1 and 13 mm from the outer periphery. In Response Surface Methodology, Central Composite Design was applied for designing the experiments and sliding wear test was conducted as per the design using a pin-on-disc tribometer for varying ranges of load, velocity and sliding distance. The model was constructed and its adequacy was checked with confirmation experiments and Analysis of Variance. The microstructural examination and hardness test revealed that the outer surface of FGM had higher hardness due to the presence of particle rich region and the inner surface had lesser hardness since it was a particle depleted region. The wear results showed that wear rate increased upon increase of load and decreased with increase in both velocity and sliding distance. Scanning Electron Microscopy analysis was done on the worn specimens to observe the wear mechanism. It was noted that wear transitioned from mild to severe on increase of load and the outer surface of FGM was found to have greater wear resistance at all conditions.
P.k. Jayashree, Sh. Raviraj, S.s. Sharma, G. Shankar,
Volume 15, Issue 2 (6-2018)
Abstract
CoHErrelation between weldability and improvement in properties is a key issue in materials science research. The objective of this work is to optimize the process parameters viz., aging temperature, aging time, solutionizing time, to enhance the hardness of Al6061 alloy. Hence, the present paper deals with hardness study of Tungsten Inert Gas welded 6061 aluminium alloy after age hardening under three different aging temperatures, aging time and solutionizing time using Taguchi’s L9 Orthogonal array. Finally, a second order model has been generated for hardness using Response Surface Methodology with 20 runs for full design. The predicted and experimental results are in good agreement.
Hamed Tavakoli, Mohammad Reza Aboutalebi, Seyed Hosein Seyedein, Seyed Nezameddin Ashrafizadeh,
Volume 18, Issue 1 (3-2021)
Abstract
Separation of samarium and lutetium was investigated through solvent extraction from their mixed aqueous species using commercial extractants of D2EHPA and PC88A. The Response Surface Method (RSM) was utilized to design the solvent extraction experiments. In which, a Central Composite Design (CCD) was applied to set the optimum conditions for highest separation factors between Sm and Lu. Design of Experiments (DOE) was conducted by making use of four operating variables, namely initial pH of the aqueous solutions (A: 0.2–2.6), extractant concentration (B: 0.01-0.09 molar), mole fraction of D2EHPA in the extractant mixture (C: 0 - 0.8) and a type of acidic solution (D: sulfuric and nitric acid) at three levels. The results indicated that the initial pH was the most paramount variable in solvent extraction of samarium and lutetium, while in the case of lutetium, the molar fraction of D2EHPA in the mixed extractants was non-influential. The statistical model predictions were confirmed by experiments for both samarium and lutetium extraction with high validity parameter of 97 and 98%, respectively. The optimum conditions for samarium and lutetium separation were identified as: A=0.8, B= 0.05, C= 0.2 and D= sulfuric acid. According to the findings of the model, the desirability value at the optimum conditions was evaluated as about 0.93, in which 71% of lutetium was extracted while the amount of extracted samarium was only less than 1%.
Ali Ebrahimpour, Amir Mostafapour, Naeimeh Hagi,
Volume 20, Issue 1 (3-2023)
Abstract
In this research, the effect of RSW parameters including current intensity, welding time and welding force (coded by A, B and C) on the radius, thickness and area of the nugget and the radius of the HAZ of TRIP steel joints was investigated by DOE and RSM. A 3D coupled thermal-electrical-structural FEM was used to model RSW. To validate the FE model, two TRIP steel sheets were welded experimentally. During welding, the temperature was measured and the results were compared with the FE results and a good agreement was obtained. The boundaries of the welding zones were determined according to the critical temperatures and the responses in all samples were calculated. Using analysis of variance, direct, quadratic and interaction effects of parameters on the responses were studied and a mathematical model was obtained for each response. The direct linear effects of all parameters on all responses were significant. But among the interaction effects, the effect of B×C on the nugget radius, the effect of A×B on the nugget thickness, the effect of A×B on the nugget area and the effects of A×B and B×C on the HAZ radius were significant. Also, current intensity had the greatest effect on all responses.
M. Reza Aboutalebi,
Volume 21, Issue 0 (3-2024)
Abstract
In recent years, Mg- based alloys have been considered as a biodegradable biomaterial for implant applications. However, the high corrosion rate and hydrogen gas evolution in an aqueous environment are the most important challenges for these alloys. This study has focused on optimizing the biocorrosion properties of bioalloys in Mg-Zn-Ca system, using a combined approach of thermodynamic simulations, and response surface methodology (RSM). In, Mg2Ca and CaxMgyZnz precipitates have a significant effect on corrosion mechanisms. It is believed that, in the Mg-Zn-Ca alloy system, the Mg2Ca secondary phase usually enhances corrosion rate with microgalvanic coupling mechanisms. The ternary phases CaxMgyZnz have less detrimental effects on corrosion resistance. To minimize harmful phases, CompuTherm’s PANDAT software was utilized for phase evolution prediction, with outputs directly validated against experimental measurements. Potentiodynamic tafel polarization experiments and long-term immersion tests were conducted to evaluate the corrosion rate. In order to design an alloy with the least detrimental phase, a statistical model (RSM) was developed based on predicted results from thermodynamic model. The results showed that the ZX31 (Mg-2.6Zn-1Ca) exhibited the highest corrosion potential (-1.6336 VAg/AgCl) and the lowest corrosion current density (216 µA/cm2), showing higher biocorrosion resistance compared to ZX24 (Mg-2.3Zn-4.0Ca) and ZX15 (Mg-1.3Zn-4.8Ca).
