International Journal of Advanced Design and Manufacturing Technology
Volume:14 Issue: 4, Dec 2021

This paper, firstly, investigates the behavior of a pressure vessel designed based on the netting analysis method. Then, the strain measurement result performed to examine the behavior of the vessel is presented. It has been observed that the reverse strain is occurred at the joint of the vessel cylindrical area and its head. To inspect the experimental data, the ABAQUS software (finite-element) was deployed. The simulation results turned out to be in good consistency with the experimental data. Later, to design the vessel, Von Mises and Tsai Wu criterion were used for liner and composite layers, respectively. The design results showed that the netting analysis method is not optimal and leads to increase in the cost and weight of the vessel. In addition, investigating the vessel behavior indicated that using softer liner results in more exploit of the composite properties which in turn, can bring better performance in special applications. The good consistency between the experimental and simulation results proved that the complexity involved in the design of pressure metal-composite vessels can be greatly reduced through employing finite-element simulation methods.

The growing development of nanobiotechnology and its applicability resulted in a wider range of use of Microcantilevers (MCs) in liquid. Considering the applications of piezoelectric MCs in the microelectromechanical systems and Atomic Force Microscope (AFM), as well as the high performance of these beams, this article investigates the vibrating behavior of multilayer piezoelectric MCs with geometric discontinuity in liquid environment. Due to the extreme complexity of hydrodynamic forces introduced to MCs, this force may reduce their accuracy. As a result, the MC was considered to be semi-submerged in the liquid medium to reduce the effect of hydrodynamic force. In addition, to reduce the effect of hydrodynamic force on vibrating behavior of the MC, sensitivity analysis was performed on its geometric dimensions to obtain the optimal dimensions, aiming at minimizing the effect of this force. The differential equation of motion was derived using the Euler–Bernoulli theory and the Lagrange method. The hydrodynamic force was exerted on the MC through the sphere string model. The Simulation results indicated that due to reducing resonance frequency variations in the third vibrating mode, the effect of hydrodynamic force on vibrating motion is minimized in this mode and considered as the optimal vibrating mode among the first three modes. The sensitivity analysis results showed that the MC length and piezoelectric layer were geometric parameters with the greatest effect on frequency sensitivity of MC, which should be considered in semi-submerged piezoelectric MC design.

In this research, the thermal analysis of additive fabrication by DMLS method has been investigated. In the DMLS method, the metal powder is melted by a laser heat source and finally a solid three-dimensional piece is formed. This analysis was performed by finite element method in Abaqus software. Laser heat distribution is considered Gaussian. The mechanical and thermal properties of the powder are considered as a function of melting temperature. Finally, the results obtained by the finite element method are compared with previous researches. The effects of laser speed and power on temperature distribution have also been investigated.

In this paper a Nth order nanoplate model is developed for the bending and buckling analysis of a graphene nanoplate based on a modified couple stress theory. The strain energy, external work and buckling equations are solved. Also using Hamilton’ principle, main and auxiliary equations of nano plate are obtained. The bending rates and dimensionless bending values under uniform surface traction and sinusoidal load, the dimensionless critical force under a uniaxial surface force in x direction are all obtained for various plate's dimensional ratios and material length scale to thickness ratios. The governing equations are numerically solved. The effect of material length scale, length, width and thickness of the nanoplate on the bending and buckling ratios are investigated and the results are presented and discussed in details.

The majority of underactuated systems are nonholonomic, due to non-integrable differential constraints. Therefore, controlling an underactuated system is considered as a challenging problem. In this study, an adaptive controller based on super-twisting sliding mode controller is proposed for a class of robust underactuated systems subjected to uncertainties and external disturbances. The adaptive compensator was designed so that there would be no need to the upper bound of the external disturbance. The controller parameters of adaptive sliding mode control are tuned based on a multi-objective non-dominated sorting of genetic optimization algorithm. The results of simulation and the demonstration of the effectiveness and applicability of the proposed scheme are presented.

Sheet metal forming is widely used in automotive and aerospace industry. In this paper analysis of sheet metal forming process by deep drawing was discussed. Static analysis on the deep drawing operation was carried out to find the stresses, strains and total deformation of deep drawing cup. CAD models are generated using CATIA from the dimensions obtained by theoretical calculations and analysis is carried out using ANSYS software. The force required to develop the cup, deformation and defect like tearing, wrinkles etc. can be obtained through simulation. By using this method it is easy to make stress and strain analysis for different materials. From the analysis it is observed that Titanium has the maximum stress with standing ability when compared to copper and Aluminum.

Pressure gradient of a two phase mixture in a horizontal pipe were experimentally investigated for water/super viscose oil mixtures. The mixture contained oil having a viscosity of 67 cp and density of 0.872 g/cm3, and pure water, flowing through an acrylic pipe having a length and diameter of 6 m and 20 mm, respectively. A high speed digital camera has been used to record visual information. Superficial velocities of water and oil were in the range between 0.18–1.2 m/s and 0.18–0.95 m/s, respectively. The experimental pressure gradient has been compared to the Al-Wahaibi correlation and two-fluid model. The absolute average error for the “two-fluid model” and Al-Wahaibi correlation have been calculated for 30% and 12%, respectively. In this investigation, a new modified correlation is developed on the basis of the Al-Wahaibi correlation, that predicts the values of pressure gradient with an absolute average error of about 9%. The pressure gradient correlation was validated extensively against 11 independent data sources. To our knowledge, this is the best pressure gradient furmola that is published for oil–water flow which includes wide range of operational conditions including fluid properties, pipe diameters and pipe materials. One of the advantages of the new proposed formula is that it also performs well for super viscosity oils.

The micro-scale equipment has many advantages, including high thermal performance, high surface-to-volume ratio in heat transfer, small size, low weight, low required fluid and high design flexibility. In this study, fluid flow inside a microchannel is modeled under the assumption of laminar, incompressible, and two-dimensional flow under symmetric boundary conditions. The slip boundary condition is applied to the walls and the flow in the channel output is assumed to be fully developed. The effect of sinusoidal wall with the domain of 0.1 on the hydrodynamic and thermal behavior of the fluid is investigated and the results are compared with the results of smooth wall. The results show that for a constant Reynolds number, the maximum velocity decreases in the microchannel center by increasing the slip coefficient. Also, the comparison between the results of the wavy-wall microchannel and the microchannel with a smooth wall indicates that the heat transfer in the smooth microchannel is less than that in wavy-wall one. Considering the boundary conditions, the thermal behavior of the fluid is approximately the same for two cases in which both walls are sinusoidal and the only upper wall is sinusoidal.

Fatigue due to thermo-mechanical stresses plays an effective role in causing damage and reducing piston fatigue life. The effect of oil gallery on the thermal stress and High Cycle Fatigue (HCF) life in a gasoline engine piston using oil gallery with considering stress gradient was investigated. For this purpose, coupled thermo-mechanical analysis of a gasoline engine piston was carried out. Then HCF life of the component was predicted using a standard stress-life analysis and results were compared to the original piston. The results of Finite Element Analysis (FEA) indicated that the stress and number of cycles to failure have the most critical values at the upper portion of piston pin. The obtained thermo-mechanical analysis results proved that the oil gallery reduces the stress distribution in the piston about 7MPa and 12MPa at engine speed 1000rpm and 5000rpm, respectively. The results of high cycle fatigue life showed that the number of cycles of failure for modified piston is approximately 33% and 37% higher than original piston at 1000rpm and 5000rpm, respectively. To evaluate properly of results, stress analysis and high cycle fatigue results is compared with real sample of damaged piston and it has been shown that critical identified areas, match well with areas of failure in the real sample.

In this paper, the free vibration of defective nanographene is investigated using Molecular Dynamics Simulation (MD) and Differential Quadrature Method (DQM). The equations of motions and the related boundary conditions are derived based on the differential constitutive relations in conjunction with the classical plate theory via Hamilton’s principle. Then, DQM is used to investigate free vibration of the nanographene with various boundary conditions. At first, in order to determine natural frequencies more realistically, nanographene mechanical properties are determined using MD simulations. The effects of defects are investigated by analyzing pristine and defective nanographenes containing Stone Wales, vacancy, and Adatom defects. According to the results, the non-dimensional fundamental natural frequency parameter converges to the analytical value for N=10×10. Results indicate that graphene with CCCC boundary conditions has the maximum natural frequency. The minimum value corresponds to the graphene with SSSS boundary conditions. In addition, Non-dimensional fundamental frequency parameter of the nanoplate increases with increasing nanoplate aspect ratio. Finally, defects reduce density, position ratio and elastic moduli of nanographene, which causes a decrease in natural frequency. Stone Wales and vacancy defects decrease nanographene natural frequencies by about 8 and 25 percent, respectively.

The design and manufacturing cubic porous scaffolds are a considerable notion in tissue engineering (TE). From Additive manufacturing (AM) perspective, it has attained high appeal in the string of TE during the past decade. In the view of TE, the feasibility of manufacturing intricate porous scaffolds with high accuracy contrast to prominent producing methods has caused AM the outstanding option for manufacturing scaffold. From design perspective, porous scaffold structures play a crucial task in TE as scaffold design with an adequate geometries provide a route to required strength and porosity. The target of this paper is achieve of best geometry to become an optimum mechanical strength and porosity of TE scaffolds. Hence, the cubic geometry has been chosen for scaffold and Cube, Cylinder and Hexagonal prism geometries have been selected for pore of structures. In addition, for noticing the porosity effects, pore size has been chosen in three size, and a whole of nine scaffolds have been designed. Designed scaffolds were generated using Fused Deposition Modeling (FDM) 3D Printer and dimensional specifications of scaffolds were evaluated by comparing the designed scaffolds with Scanning Electron Microscope (SEM). The samples were subjected to mechanical compression test and the results were verified with the Finite Element Analysis (FEA). The results showed that firstly, as the porosity increases, the compressive strength and modulus of elasticity obviously decreased in all geometry pore scaffolds. Secondly, as the geometry changes in similar porosity, cubic pore scaffold achieved higher compressive strength and modulus of elasticity than cylinder and hexagonal prime. Experimental and FEM validated results proposed a privileged feasible pore geometry of cubic scaffold to be used in design and manufacturing of TE scaffolds.

In this study, effects of process parameters of Friction Stir Spot Welding were investigated on Al2024T3 which has poor weldability. Several spot welds were performed by the FSSW process on the 2mm aluminium sheets. The effects of main process parameters such as tool Rotational Speed (RS), Normal Plunge Depth (NPD), and Dwell Time (DT) on the joint strength were investigated. By increasing the tool rotational speed, the joint strength increased, consequently. The mean failure load improved 52% when the tool rotational speed increased from 800 rpm to 1120 rpm, whereas increasing the rotational speed from 1120 to 1600 did not have significant effect on the failure load. The results showed, increasing the normal plunge depth from 1.5 to 1.75 millimetre led to an increase in the failure load of spot welds by about 1.62 times. Also, the 3 seconds dwell time showed higher failure load compared to 2 and 5 seconds dwell time.

This paper presents a model to predict Material Removal Rate (MRR) in Micro Ultrasonic Machining (micro-USM). The proposed model is developed based on the ductile-mode of material removal in micro-USM process. The correlation between ductile material removal rate and process parameters including frequency and amplitude of the ultrasonic vibration, particle size, and slurry concentration is presented. The proposed predictive model is verified by performing micromachining experiments using two types of workpiece materials including silicon and quartz at various process parameters levels. The results show that the MRR increases with a rise in vibration amplitude for both silicon and quartz materials. The experimental MRR values follow a trend similar to that of predicted MRR values. However, the predicted MRR values are higher than the measured MRR values for both silicon and quartz materials. The measured MRR values for ductile removal mode were found to have a considerable increase at vibration amplitudes of 2 mm and 2.4 mm for silicon and quartz, respectively, which is in favour of increasing the accuracy of the model prediction.