International Journal of Advanced Design and Manufacturing Technology
Volume:16 Issue: 3, Sep 2023

Liquid sloshing is a common phenomenon in the transporting of liquid tanks. A safe liquid transporting needs to control the entered fluctuating forces to the tank walls, before leading these forces to large forces and momentums. Using predesigned baffles is a simple method for solving this problem. Smoothed Particle Hydrodynamics is a Lagrangian method that has been widely used to model such phenomena. In the present study, a three-dimensional incompressible SPH model has been developed for simulating the liquid sloshing phenomenon. This model has been improved using the kernel gradient correction tensors, particle shifting algorithms, turbulence model, and free surface particle detectors. The results of the three-dimensional numerical model are compared with an experimental model, showing a very good accuracy of the three-dimensional numerical method used. This study aims to investigate vertical baffle effects on the control and damping of liquid sloshing. The results of the present investigation show that in this particular case, by using baffles, it is possible to reduce more than 50% of the maximum value of pressure fluctuations in the slashing phenomenon.

One of the most challenging issues in DLP 3D printing is separation. Thus, the capability to employ a variety of polymer membranes can considerably aid in the development of the DLP technology. The primary purpose of this study is to thoroughly explore the characteristics influencing separation force and time on the FEP industrial membrane and the proposed PP membrane. Therefore, the impact of image cross section geometry and separation speed on separation force and separation time is investigated. As a consequence, changing the percentage of surface porosity has a negligible effect on the amount of separation force. According to the findings, reducing the cross-sectional area by 1.36% reduced the separation force by 6.5 times. Moreover, the outcomes are consistent with the mathematical model given. the separation force rose by 230% in the FEP membrane with an increase of 96 times of the speed, whereas the separation time decreased by 18.8 times. For the proposed PP membrane, as the speed increases, the separation force rate increases by 175% and the separation time falls by 29.6 times. The aforementioned findings show that the PP film may be used as a practical and affordable solution with quick separation that can reduce printing time when producing three-dimensional lattice pieces at varying speeds.

Increasing the stability of structures and reducing the maintenance cost of slab track superstructures compared to ballasted tracks are among the reasons for the tendency to use this category of superstructures in the railway industry. Vibration reduction methods can be divided into three categories, source, propagation path, and receiver. In general, the slab track structures in Iran are divided into three categories: direct fixation track (DFT), floating slab track (FST), and high resilient fastener (HRF). Although railway tracks are a safe, economical and fast transportation system and can lead to the strengthening of the tourism industry, in the long term, vibrations can damage many historical structures in the city of Isfahan. FST and HRF systems are used in the structure of Isfahan subway track. In this paper, the accelerations (longitudinal, lateral, and vertical) of the Isfahan subway vehicle were measured in 30 stations (15 go stations and 15 return stations). The results showed that the HRF system compared to the FST has a significant effect in reducing the range of vibrations and ultimately the safety of the train and the ride comfort. For example, in the area between Si-O-Se-Pol and Imam Hossein Square, due to the track structure type (HRF), the maximum acceleration and RMS acceleration are in the range of 1.5 and 0.3 m/s2, respectively, while in other stations these values were extracted up to 4 and 0.7 m/s2, respectively.

Piezoelectric Microcantilevers (MCs) are efficient tools in switches of MEMS, AFMs and nano-resonators. Creating maximum vibrating motion with minimum excitation voltage is important in reducing power consumption and noise in this type of MCs. Therefore, investigating the factors affecting the excitability of MCs, as well as the degree of the effect of each of these factors, have an important role in the design and optimal selection of this type of resonators. Therefore, the aim of this paper was to investigate the excitability of this type of MCs. Modeling is conducted according to Hamilton principle and Euler-Bernoulli theory. Equation of motion was solved using Galerkin method with respect to geometrical discontinuities. Finally, eFAST sensitivity analysis was performed on excitability of MCs using statistical methods. Sensitivity analysis results show that the length and thickness of the piezoelectric layer are the most influential parameters on the excitability of MCs. At L1/L=0.74, the excitability reaches its maximum value.

In the analysis of contact mechanics problems, determination of stress field in mechanical elements is essential. Between the stress components the von Mises stress is more important, because it is used in the investigation of yield criteria and fatigue fracture of elements. The aim of this study is to present formulas for determining the magnitude and position of maximum von Mises stress. For this purpose, the effect of various material properties, element geometries and loading conditions on these two parameters are investigated. By applying Hertzian contact stress and von Mises relations, the magnitude and position of maximum von Mises stress are determined. The von Mises stress is assumed to be a function of material properties, geometry of the element and loading conditions and finally two formulas are presented for the calculation of the magnitude and position of maximum von Mises stress. The results of these presented formulas are in close agreement with the literature. The error is less than 1% for depth prediction and less than 6% for stress value prediction, which confirms the accuracy of the presented formulas.

Channels have various types of cross-sectional shapes, including trapezoidal, rectangular, semi-circular, parabolic, chain-curved, semi-cubic parabolic, egg-shaped, and circular as the most common shapes. A channel designer has many design options in different conditions, including hydraulic, economic, and hydrological conditions, leakage, etc. Among the above-mentioned sections, the first two have a horizontal bottom while the other sections are curve-shaped with bottom curvature. The primary goal in the design of hydraulic channels is to achieve the maximum flow capacity considering the minimum channel construction cost. A variety of studies has been conducted on the different types of hydraulic channels so far, each dealing with the subject from a certain perspective. However, most of the studies have focused on circular, rectangular and trapezoidal channels. This study has focused on the parabolic channel. Genetic algorithm (GA) and particle swarm optimization (PSO) or GRG algorithms and their combination are usually used for optimization. However, this research adopts a novel and updated meta-heuristic algorithm, namely the Harris Hawks Optimization (HHO) algorithm, to optimize the parabolic channel with a fixed roughness coefficient and determine the optimal dimensions of the channel with different flow rates. This channel uses different flow rates, namely 50, 100, 150, 200, 250, and 300 m3/s to solve the optimization problem. Finally, it was found that the lowest construction cost and the highest efficiency for water supply is achieved with a roughness coefficient of 0.015 and a flow rate of 100 m3/s.

Fiber‐metal laminate is a material constituted of composite laminate and metal sheets, whose mechanical properties can be tailored by varying the thickness, the number of layers and bonding type. For this reason, in this research, strength test, adhesion test and flux test for a sandblasted and etched aluminum sheet that contained a seven-layer composite with 2 types of adhesion treatment (phenol adhesive/resin of composite material) and front side composite layup (High-silica/High-silica+Carbon) were investigated. It was found that the above-mentioned factors influenced the flexural strength of FML; precisely, the presence of an adhesive layer between the composite plies and the metal sheet made the flexural strength decrease, while this mechanical parameter increased passing from two metal sheets to only one. The results show that the presence of carbon layer has led to the greatest increase in strength due to strong bonding. Also, the results of the flux test show that the behavior of the two samples is very close to each other.

The effect of perimeter fins on the thermal stress and High Cycle Fatigue (HCF) life in an exhaust manifold with considering stress gradient was investigated. For this purpose, coupled thermo-mechanical analysis of an exhaust manifold was carried out. Then HCF life of the component was predicted using a standard stress-life analysis and results were compared to the original exhaust manifold. Mechanical properties of exhaust manifold material were obtained by tensile tests at different temperature. The results of the thermo-mechanical analysis proved that the maximum temperature and stress are visible in the confluence region. The obtained Finite Element Analysis (FEA) proved the fact that perimeter fins reduce the temperature distribution in the exhaust manifolds about 31°C. As a result, the exhaust manifolds tolerate lower temperature and fatigue life will increase. The results of FEA indicated that the stress in the modified exhaust manifolds decreased approximately 19MPa for the sake of depletion of temperature gradient, which can lead to higher fatigue lifetime. The results of HCF showed that the number of cycles of failure for modified exhaust manifold is approximately 63% higher than the results obtained from the original exhaust manifolds. The results of the FEA analysis are compared with the real sample of the cracked exhaust manifold to properly evaluate the results, and it has been shown that critical identified areas correspond to the failure areas of the real sample.

This study is devoted to analyse of free and forced vibrations and semi-active control vibrations of sandwich microbeam with Functionally Graded Materials (FGM) and viscoelastic/electrorheological (ER) core. The intended model is for top and bottom layers of functionally graded materials with power law and a core model for Viscoelastic materials with complex shear modulus. Hamilton principle is used to determine the governing Equations of motion on the sandwich microbeam based on the modified couple stress theory. Mesh less method of Radial Basis Functions (RBF) is used to calculate natural frequency and the loss factor. All the effects of length scale parameter, shear modulus and changes due to variation of the electric field on the natural frequency and loss factor have been drawn. Combination of RBF method and forward difference led to evaluation of forced vibration and deflection of microbeam for length scale parameters and different electric fields under the dynamic load have been calculated and drawn. The feedback effects are analyzed for vibration amplitudes of sandwich microbeam by using Linear Quadratic Gaussian (LQG) and optimal control method. At the end, the results are compared with papers for different viscoelastic models such as Kelvin model, Bingham plastic model and complex modulus.

Nowadays metal matrix composites are popular in many industries due to their desirable properties. Severe plastic deformation techniques usually are popular to fabricate metal matrix composites. In this study and as its novelty, Al/Gr composites have been manufactured via a new novel technique, powder metallurgy and press bonding process. Then, as a function of Gr as additive part in this study, tribological, mechanical and microstructure properties of Al/Graphite composites were studied. The tribo surface and microstructure of composites have been investigated more over using SEM microscopy. The density and wear rate of samples increased and the hardness and friction coefficient decrease and by increasing the Gr content. Results showed that addition of Gr into Al matrix can improve the tribological properties of composite.