جستجوی مقالات مرتبط با کلیدواژه "response surface method" در نشریات گروه "مکانیک"

Contact and friction in moving systems cause heat generation and this factor affects the properties and performance of parts. The purpose of this research is to investigate the effect of speed, pressure, and friction coefficient parameters on the heat produced in a linear sliding system. In this regard, a finite element model of a linear reciprocating compressor piston assembly was used and the results were validated using experimental data. Also, the response surface method and ANOVA analysis were utilized in the design of experiments and analysis of the results. Investigation of the results showed the parameters of speed, friction coefficient, and pressure have a direct relationship with temperature, speed has the greatest effect and pressure has the least effect on the produced temperature. Increasing the speed causes to increase the heat production, but the effect of increasing the pressure is the result of increasing the heat caused by increasing the friction force and reducing the heat caused by increasing the effective contact surface and better heat transfer.

In this research, the modeling of a solar renewable system along with the use of intelligent optimization method was discussed in order to increase the system performance and reduce the life cycle cost. A system with a combination of five units of PVT panel, heat pump, PEM electrolyzer, hot water storage source and fuel cell was designed to provide the required energy consumption of an 80-unit residential complex in Iran, including hot water, cooling, heating and electricity. The performance of the proposed system was analyzed by using the weather information of the coastal city of Bandar Lengeh in Hormozgan province. System modeling was done using a new approach by TRNSYS software. Optimization of this system to increase system performance and reduce life cycle cost was done by Design Expert software and using RSM. The three objective functions investigated included electricity production, PMV and LCC, and four decision variables including the number of solar panels, fuel cell capacity, heat pump capacity and electrolyzer capacity were selected. The optimization results showed that in the most optimal state with the number of 1425 solar panels, the capacity of 65.99 kW for the fuel cell, the capacity of 40.01 kW for the heat pump and the capacity of 52.5 kW for the electrolyzer are in the optimal state. The system can reach the production value of 725955.25 kWh per year in the optimal condition with a PMV of 0.43 and a LCC of 344014.63 $.

Using latent heat storage systems with phase change materials (PCM) is an effective way to store thermal energy, which has been of great interest recently. Using fins is one of the simplest and cheapest ways to increase heat transfer in PCMs and increase the performance of the storage system. Since the fin arrangement has a significant impact on the charging time of the PCM, the main goal of this study is to optimize the fin arrangement in the PCM chamber in a double-pipe heat exchanger in order to decrease the charging time, and thus increase the efficiency of the storage system. For this purpose, the governing equations including conservation of mass, momentum, and energy in a finned double-pipe heat exchanger have been solved using ANSYS-Fluent software to investigate the dynamic behavior of PCM. The thermal-hydraulic performance of PCM at different configurations has been fully analyzed by drawing liquid fraction contours, velocity vectors and streamlines. Also, to find the optimal fin arrangement and maximize the storage performance, the response surface method based on the central composite design have been implemented. The results obtained from the response surface with the reduced cubic equaltion show that compared to the case without fins, the charging time reduces by about 19% using the uniform fin configuration, while reduces about 56% using the optimal fins arrangement, which is a significant amount.

In recent years, additive manufacturing has gained significant importance in the field of production. Most of the additive manufacturing technologies for metals involve melting and solidification processes, leading to metallurgical challenges. The friction stir additive manufacturing process is a novel solid-state method that does not face the common metallurgical challenges associated with the traditional melting methods. This process can be used for the production of aluminum-silicon carbide nanocomposites that find many applications in industries such as military, aerospace, automotive, etc. The primary objective of this research is to experimentally analyze the effect of tool rotational speed, tool traverse speed, and number of passes in friction stir additive manufacturing on the microhardness and wear amount of aluminum-silicon carbide nanocomposite manufactured by this method. To this end, the response surface method and Minitab software were used for experimental design, statistical analysis, and optimization of the parameters. Multi-objective optimization settings were selected to increase microhardness and reduce wear. The combinations of optimal values of the parameters were determined to achieve the optimization goals, and the results were validated. The optimization result with 0.87 desirability is obtained with a tool rotational speed of 1000 rpm, a tool traverse speed of 50 mm/min, and one pass. The predicted optimal responses of 104 Vickers for microhardness and 0.013 gr for wear had a small percentage of error compared to the experimental results.

In this paper dielectric barrier discharge plasma actuator effect on flow separation of a horizontal axis wind turbine blade section were studied. Firstly, two dimensional flow simulations of plasma actuator with improved electrostatic model were performed in various operational conditions and angle of attacks. Then, an explicit response surface mathematical model was derived for the effect of variables on aerodynamic coefficients. Separation zone shrinkage was observed as a consequence of momentum injection from plasma actuation. The mathematical model has an acceptable validity and shows the significant interaction between parameters. Finally, a MATLAB code was developed to implement blade element momentum method and evaluate the mechanical output power of Tellus 100 kW wind turbine with actuator operation. The results indicate no significant effect on output power for cut-in to 10 m/s wind speeds and an increase of about 11 percent for 11 to 16 m/s speeds.

Magnetic abrasive finishing process (MAF) is one of the latest advanced machining processes. After eight decades have passed since the registration of the magnetic abrasive polishing process, the applicability of this method has been proven in finishing all kinds of surfaces, including flat, cylindrical and free surfaces. In this research, the influence of MAF process movement parameters on the concave surface of cold-worked steel has been investigated experimentally using the response surface method. These parameters include rotational speed, linear speed, gap between abrasive brush and workpiece, magnetic flux density and curvature angle. For this purpose, a spherical head magnet is used and the powder used is prepared by mechanical alloying method. Cold-worked steel is used in the manufacture of roll forming molds, which is used in air engines to shape compressor and turbine blades, and also to investigate the feasibility of the MAF process on the workpiece surface with high hardness and yield stress, such as Cold work steel is selected. According to the results, the optimal value of the magnetic flux density is 0.55 tesla, and with the increase of the distance between the abrasive brush and the workpiece, the surface roughness changes initially increase and decrease after passing the optimal value.

4D printing is an emerging phenomenon of additive manufacturing which is achieved by the 3D printing of shape memory materials. The printed parts can change their shapes when exposed to an external stimulus by controlling the 4D printing process. In this study, a relationship between applied pre-stress in the printing process and the amount of bending shape recovery was obtained using numerical simulations. Then, the effect of printing parameters of fused deposition modeling including layer thickness, printing speed, and nozzle diameter on the applied pre-stress in the printed polylactic acid parts was investigated. To reduce the cost and time as well as to increase the validity and accuracy, the central composite design method was used. Seventeen experimental tests were performed and a model was obtained between the mentioned parameters and applied pre-stress. In the following, R2 and Adj R2 of the model were obtained above 0.99 and 0.98, respectively, which indicates the high accuracy of the model. The model showed that the layer height, nozzle diameter, and printing speed have a significant effect on the applied pre-stress. Also, the applied pre-stress is inversely related to the layer height, nozzle diameter and is directly related to the printing speed. Simulations were performed under the conditions of maximum bending shape recovery and compared with the experimental model. The results showed that the error of the relationship between applied pre-stress and amount of shape recovery is 1.5% and the experimental model of printing parameters effect on the shape recovery is completely matched.

Nowadays, the use of lasers in welding titanium alloys has special applications in high-tech industries. This study aims to extract the statistical model showing the effect of changes in the diameter of laser beam diameter and distance in line thickness welding temperature. At first, For establishing this model, the required experiments were designed by the Taguchi method and then evaluated using the finite element method. The surface response method is used to extract the statistical model based on the variation of laser beam diameter and distance through the workpiece thickness. By the analysis of the variance, the statistical model error was evaluated in an acceptable range. According to the evaluated results, the influence percent of the distance along with the workpiece thickness and the laser beam diameter is 76.67 and 97 %, respectively, on the welding temperature. By increasing the diameter of the laser beam, the amount of the welding temperature is significantly reduced. For laser welding of Ti6Al4V, the best laser beam diameter is between 0.2 and 0.24mm.

The ECAP-Conform is one of the newest and less known processes that improve mechanical properties. In the present study, the effective parameters of the ECAP-Conform process for AA7075 have been investigated. Influence of parameters such as roller radius, bending angle, die channel angles, rod/roll friction coefficient, rod/die friction coefficient, and the aspect ratio of the die groove on the torque, the applied force on the die, the stress, and the effective plastic strain, the output rod curvature, and the strain distribution uniformity have been investigated. The design of experiments was carried out based on the response surface method by the Minitab software, and simulations were performed using the ABAQUS software. To validate the FEM, the ECAP-Conform process of AA7075 rod was performed and the comparison of experimental and numerical results have acceptable compliance (7.5% error). It was found that the die channel angles and the rod/die friction coefficient have a more significant effect on all responses. Moreover, to maximize the imposed strain and strength, and to minimize the process torque and curvature, as well as achieving a uniform distribution of strain, the optimal output parameters have been obtained.