Journal of New Applied and Computational Findings in Mechanical Systems: 4 (4)

Open Access Article

1 - Particle swarm optimization in optimal control problems for Car on a constrained piecewise affine hill
Ahmad Kia Kojouri Javad MashayekhiFard

In spite of all the Demonstrate Prescient Control (MPC) based arrangement preferences such as ensuring soundness, the most impediment such as an exponential development of the number of the polyhedral locale by expanding the expectation skyline exists. This causes an in More

In spite of all the Demonstrate Prescient Control (MPC) based arrangement preferences such as ensuring soundness, the most impediment such as an exponential development of the number of the polyhedral locale by expanding the expectation skyline exists. This causes an increase in the computation complexity of control law. In this paper, we consider the arrangement to ideal control issues for constrained piecewise affine systems based on demonstrating predictive control. After that, we utilize particle swarm optimization calculation to complexity diminishment of arrangement and alter the framework execution. In truth the point of the paper is twofold. To begin with, we consider the hypothetical comes about on the structure of the control law. At the minute, we portray how the complexity of deciding control law can be capable of decreased and moving forward system execution at the same time by utilizing particle swarm optimization. The considered calculation is associated with a Car on a constrained piecewise affine hill and the result is shown to the advantage of our analysis. The objective of the car is to climb to the top of a steep slope and then preserve its position at the top (the beginning), without falling from the piecewise affine environment. The number of control law polyhedrals diminishes from 129 to 25. Manuscript profile

Open Access Article

2 - Multiaxial fatigue analysis of exhaust manifold with considering viscosity stress
Hojjat Ashouri

Due to the complex geometry and loading conditions, exhaust manifolds are the most challenging components among all parts of engines. They must withstand severe cyclic thermo-mechanical stresses throughout their lifetime. Thus, simulation and analysis of fatigue cracks More

Due to the complex geometry and loading conditions, exhaust manifolds are the most challenging components among all parts of engines. They must withstand severe cyclic thermo-mechanical stresses throughout their lifetime. Thus, simulation and analysis of fatigue cracks is essential. In this paper, low cycle fatigue (LCF) life analysis of the exhaust manifold is performed by using the finite element method and ABAQUS software to predict the temperature and stresses and then LCF life by using Brown-Miller theory and MSC-FATIGUE software. The combination of the Chibcha nonlinear isotropic-kinematic hardening model with viscous stress law is used to consider the effect of viscosity stress. The results of finite element analysis showed that the maximum temperature and stress values in the exhaust manifold are 757.7°C and 395.2MPa and the position is at the confluence region. Therefore, the confluence area of the engine exhaust manifold is a critical area and there is a possibility of possible cracks in it. The fatigue life of the exhaust manifold without and considering the effect of viscosity stress was calculated as 9310 and 8850 cycles. In other words, neglecting the viscosity effect caused an estimation of 460 cycles or about 5.2% higher than the limit. Therefore, it is necessary to consider the viscosity effect in the analysis of the low cycle fatigue life of the exhaust manifold. Manuscript profile

Open Access Article

3 - Redesigning and implementation of the FDM 3D-Printer for Increasing Print Accuracy by reducing vibrations
Omid Sarabi Farzad Cheraghpour Samavati

Fused Deposition Modeling (FDM) 3D printing is one of the fast-growing types of Rapid Prototyping (RP) technology. 3D printing refers to fabricating a physical object from a 3D digital model by laying down successive thin layers of material. The mechanical properties an More

Fused Deposition Modeling (FDM) 3D printing is one of the fast-growing types of Rapid Prototyping (RP) technology. 3D printing refers to fabricating a physical object from a 3D digital model by laying down successive thin layers of material. The mechanical properties and quality of the printed objects are extensively dependent on various print parameters. This study aimed to find optimized tuning parameters of print such as nozzle diameter and speed and temperature of print to improve accuracy in the prototyped part. For this purpose, the type and material of the employed profiles were first improved during the structural design of the printer, such that the structural vibrations of the device were removed considerably. Secondly, the nozzle vibrations were reduced by the redesign of the printer’s extruder. The stop/start movement of the axes was optimized through the control of the driving stepper motors of the printer’s axes. The effect of these three optimization steps enhanced the accuracy of the printer to a considerable extent. In The experimental tests, various combinations of print parameters have been examined to find the best settings. Printing of the standard model evaluated the accuracy of the printer and confirmed the validity of the results. Manuscript profile

Open Access Article

4 - Simulation of thermal stress in the hot rolling process and its effect on roller failure
Amirheshmat Khedmati Bazkiaei Ali Sozangar

The rolling process is actually the shaping of steel, in which rollers are used to change the shape, improve the mechanical properties of the material, and eliminate the uniformity of the metal. Steel can be rolled in two forms, hot and cold, each of which has its chara More

The rolling process is actually the shaping of steel, in which rollers are used to change the shape, improve the mechanical properties of the material, and eliminate the uniformity of the metal. Steel can be rolled in two forms, hot and cold, each of which has its characteristics. The purpose of this research was to investigate the effect of thermal stress during the rolling process on the failure of rollers using finite element simulation. This construction is non-linear and it is hypothesized that the roller is isotropic, without cracks and thermal strain, and the temperature of the environment is similar to the room. In this research, the effect of basic and accurate cooling during the rolling process has also been investigated. The results obtained in six hot rolling are created according to the highest number of rollers and the number of rollers in the rollers, which is shown and the extent of the role of thermal stresses on the failure of the rollers is stated Manuscript profile

Open Access Article

5 - Thermal performance enhancement of latent heat storage system using wavy fins and change in tube geometry
Rahman Hamid zahra mehrdoost

In this work, thermal performance improvement of the latent heat energy storage system using wavy fins and change in the heat transfer fluid tube geometry is numerically investigated. The investigated system is a shell and tube heat exchanger and RT35 paraffin is used a More

In this work, thermal performance improvement of the latent heat energy storage system using wavy fins and change in the heat transfer fluid tube geometry is numerically investigated. The investigated system is a shell and tube heat exchanger and RT35 paraffin is used as the phase change material. With the constant total cross-section area of the tube and fins as well as the volume of the phase change material, the effect of heat transfer fluid tube shape and the designed fin on the melting process of the phase change material is investigated. Numerical simulation results show that wavy fins accelerate the phase change process compared to conventional straight fins. The complete melting time of the phase change material is reduced by 9.33% compared to the straight fin. Changing the geometry of the heat transfer fluid tube from the circle to the petal shape is proposed to further improve the thermal performance of the latent heat energy storage system. The melting rate of the phase change material increases with the increase in the number of petals. The complete melting time for the tube with seven petals is reduced by 66.7% compared to the circular tube with wavy fins and 69.8% compared to the base case with straight fins. Manuscript profile

Open Access Article

6 - Investigating the performance of several frequency domain and time domain methods in calculating the dynamic parameters of a three-story structure using operational modal analysis
Mohsen Mahdavi Adeli Hesam Makvandi

In this research, a practical method for finding modal parameters in structures is investigated. At first, two methods in the frequency domain called FDD and EFDD frequency domain analysis methods and a time domain method called SSI are defined. In order to check the ac More

In this research, a practical method for finding modal parameters in structures is investigated. At first, two methods in the frequency domain called FDD and EFDD frequency domain analysis methods and a time domain method called SSI are defined. In order to check the accuracy of these methods in identifying the modal parameters of real structures, a three-story structure modeled in Ansys software will be used. This structure was modeled by Ansys software and the correctness of the model performance was confirmed by comparing the results of modal analysis of the structure with the results of experimental tests. The acceleration response obtained from the created model is given as an input to environmental modal analysis methods, whose responses are compared with actual results. It was observed that all three methods could estimate the frequencies, mode shapes and damping coefficients of the structure with high accuracy. It is also observed that using the SSI method is easier, but the FDD and EFDD methods need less time to solve. Manuscript profile

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