Papers by Keyword: Response Surface Method (RSM)

Abstract: The aim of the present paper is to study the vibration behavior of a sandwich structure with honeycomb core experimentally and numerically with different design parameters. The natural frequency and damping ratio were obtained. Core height, cell angle and face thickness were considered as design parameters. Finite element models for the honeycomb sandwich were developed and analyzed via ANSYS finite element analysis (FEA) software. Response Surface Method (RSM) is used to establish numerical methodology to simulate the effect of the design parameters on natural frequency and damping ration. The employment of (RSM) provides a study of the effect of design parameters on natural frequency and damping ratio, numerical modeling of them in term of design parameters and specifying optimization condition. The experimental tests were conducted on sandwich specimens for the validity goal of the previous models created via the finite element analysis. The obtained results show that the natural frequency is directly proportional to the core height and face thickness, while it is inversely proportional to cell angle, Vice versa for damping ratio. Moreover, the optimum value of natural frequency (209.031 Hz) as minimum and damping ratio (0.0320) as maximum were found at 4.8855 mm of core height, 26.770 cell angle and 0.0614 mm face thickness.

Abstract: The present paper concerns with studying the high complexity nature of the EDM multiple discharge analysis transformed into a feasible solvable mathematical model for the die steel workpiece type AISI D2, the copper and graphite materials electrodes, and the kerosene dielectric by setting the Transient Thermal and the Multiphysics analyses domain loads models using the ANSYS 15.0 finite element analysis. Two load steps modeled the entering setting time analysis, six sub-periods setting time cycle, four heating, and two cooling periods, six transient temperature values, and four transient thermal convection models. The radius spark (discharge channel), the total number of discharges sparks, the total heat power generation, the absorbed heat flux fractions by the electrodes, the workpieces and kerosene fluid dielectric, the heat-affected zones (HAZ), the hard white recast layer thickness (WLT) and properties, the workpiece fatigue safety factor and life after EDM machining were determined and simulated. The thermal model errors compared with theoretical calculations and a modeled predicted equation were also deduced and verified. The experimental results evinced that the maximum total heat flux generated using the graphite material electrodes is (2.619E+009 W/m2) which is higher than when using copper material electrodes by (82.4%), while the minimum value of the white layer thickness (WLT) after EDM machining using graphite tool electrodes is (8.34 μm), which it gives an improvement comparing with using of copper tool electrodes by (40.0%). The macrographic and microstructure evaluation manifest that the discharge spark craters sizes when using graphite tool electrodes reached their sizes. The maximum fatigue stresses and fatigue safety factor when using copper tool electrodes are (240 MPa) and (0.89) which is higher by a value of (3.35%) and (3.45%) comparing with the using of graphite electrodes, respectively.

Abstract: Single-point diamond turning is a technique of ultra-high precision machining that provides excellent quality of surface for mirrors, spherical and aspherical components. In SPDT just like other machining processes, cutting fluid plays an important role in metal removal and tool condition which largely influence the surface of diamond turned surface. In this paper, the surface roughness of diamond turned RSA 431 was studied by investigating the effect of kerosene mist and water as cutting fluids. Higher order response surface of Box-Behnken design was generated using fewer runs than a normal factorial technique. The cutting parameters that were varied for both experiments were depth of cut, feed and, speed. Taylor Hobson PGI Dimension XL surface Profilometer was used to measure the surface roughness after each experimental run. The results show that water when used as cutting fluid during machining, produces better surface roughness than kerosene mist. Predictive models for surface roughness were developed for each experiment. Values from the Mean Absolute Percent Error (MAPE) was used to evaluate and compare the two models to determine the accuracy. RSM also proved to be a better methodology of predicting surface roughness.

Abstract: This paper is a presentation of a comparative study of the effect of water and kerosene coolants on surface finish during ultra-high precision diamond turning (UHPDT) of Rapidly Solidified Aluminium alloy (RSA 443). The percentage relative difference between the coolants’ surface roughness values is denoted by the ΔR_a parameter. The accuracy of the Response Surface Method (RSM) in predicting surface roughness of water and kerosene-based results is investigated in this paper. The cutting parameters used in the investigation are cutting speed, feed rate and depth of cut. The Taguchi method was used to design the experiment since it provides relatively fewer experimental runs when compared to classical experimental design methods. Mean Absolute Percentage Error (MAPE) values are used to compare RSM’s surface roughness prediction accuracy on both water and kerosene-based results. It is observed that the surface roughness profiles for either coolant are similar, and the use of water coolant yields smoother surface finishes when compared to the use of kerosene. It is also observed that RSM displays better accuracy in predicting water-based surface roughness.

Abstract: The probabilistic design analyses a plate involving uncertain input parameters. These input parameters (geometry, material properties, boundary conditions, etc.) are defined in the software model. The variations of input parameters are defined as random input variables and are characterized by their distribution type (Gaussian, lognormal, etc.) and by their distribution parameters (mean values, standard deviation, etc.). During a probabilistic analysis, software executes multiple analysis loops to compute the random output parameters as a function of the set of random input variables. The values for the input variables are generated either randomly (using Monte Carlo simulation) or as prescribed samples (using Response Surface Methods). In the conclusion, some results of these probabilistic methods are presented.

Abstract: This paper describes the nonlinear probabilistic analysis of the failure pressure of the shielding plate of the reactor box of the nuclear power plant under a high internal overpressure and temperature. The scenario of the hard accident in Nuclear power plant (NPP) and the methodology of the calculation of the fragility curve of the failure overpressure using the probabilistic safety assessment PSA 2 level is presented. The fragility curve of the failure pressure was determined using 45 probabilistic simulations using the response surface method (RSM) with the Central Composite Design (CCD) for 10⁶ Monte Carlo simulations for each model and 5 level of the overpressure.

Abstract: Phenol is a carcinogenic, toxic and chemically stable-benzene ring compound that commonly exists in myriad industrial effluents. In this study, phenol degradation was carried out by Zn/TiO₂ photocatalyst synthesized by sol-gel method that photoactive under visible light. The effect of parameters; pH level, phenol concentration and irradiation time on phenol degradation were studied using Response Surface Methodology (RSM). The optimum condition was at irradiation time of six hours, pH 8 and phenol concentration of 130 ppm. The SEM analysis on Zn/TiO₂ photocatalyst revealed the agglomerated morphology that enabled photoactivity under visible light.

Abstract: The selection, fitting and evaluation methods of response surface functions are expounded. The parameter sensitivity analysis of the cabin is carried out. The response surface functions of the stress and the vibration frequencies are constructed through the Box-Behnken experimental design method. Fitting inspection on the response surface functions is done with correlation coefficient, correction coefficient, etc. The results show that the response surface models are very similar to the real models. Four design variables are extracted randomly as the test sample of each response surface function. The data gotten by the response surface function are compared with the data gotten by the finite element analysis. The results show that the response surface models are with high accuracy and can reflect the real test values well. These response surface models can be used for further optimization design. They are helpful in reducing the ship mass without exceeding the allowable stress and resonance.

Abstract: The Cu/TiO₂ photocatalyst preparation variables namely Cu loading, calcination temperature and calcination duration were optimized using response surface methodology. A set of experiments were conducted to obtain the response data which was then analyzed using Design Expert software. The analysis of variance revealed that COD removal from aqueous DIPA solution fitted a quadratic polynomial model with high coefficient of determination (R² = 0.99). The Cu loading was found to be the most significant variable, which then followed by calcination time and the least significant variable was calcination temperature. The optimum condition for the preparation of Cu/TiO₂ photocatalyst for photodegradation of aqueous diisopropanolamine solution was observed at 1.8 wt% Cu loading calcined at 425 °C for 1.0 h. At the optimum condition, 61.15 % of COD removal was achieved. The optimum conditions of the current study will be used for kinetic study.

Abstract: AISI 304L is an austenitic Chromium-Nickel stainless steel offering the optimum combination of corrosion resistance, strength and ductility. These attributes make it a favorite for many mechanical components. The paper focuses on developing mathematical model to predict ultimate tensile strength of pulsed current micro plasma arc welded AISI 304L joints. Four factors, five level, central composite rotatable design matrix is used to optimize the number of experiments. The mathematical model has been developed by response surface method. The adequacy of the model is checked by ANOVA technique. By using the developed mathematical model, ultimate tensile strength of the joints can be predicted with 99% confidence level. Contour plots are drawn to study the interaction effect of pulsed current micro plasma arc welding parameters ultimate tensile strength of AISI 304L steel. The developed mathematical model has been optimized using Response Surface Method to maximize the ultimate tensile strength.