Journal of Computational Applied Mechanics
Volume:52 Issue: 1, Mar 2021

Ball valve is one of valves that have many applications in industry especially in gas delivery systems. This kind of valve is categorized in the on - off flow control valve. This study aims to investigate unusual application of ball valve to control fluid flow in industry and its destructive effect including erosion of ball and body of valve. Simulation of industrial ball valve is done using ANSYS Fluent software and effect of erosion on it is investigated in different working conditions. In this article, working condition is performed regarding 2 different concentrations for suspended particles as well as four positions of ball in different angles. We assess the effect of increased particle diameter on the rate of erosion for three diameters (3.86e-6 m , 267.45e-6 m and 531.03e-6 m) in four conditions of valve (25%, 50%, 75% and 100%) and two different concentrations of particle (3% and 6%). It is shown that rate of erosion is increased with increased particle diameters in 25%, 50% and 75% open state of valve. On the contrary, the results show that opposite rule governs complete open state. Furthermore, it is demonstrated that increase in particle diameter decreases the area of erosion in four conditions of valve.

Abstract of the paper: Electroosmotic flows of two-layer immiscible Newtonian fluids under the influence of time-dependent pressure gradient in the flow direction and different zeta potentials on the walls have been investigated. The slippage on channel walls is, also, considered in the mathematical model. Solutions to fluid velocities in the transformed domain are determined by using the Laplace transform with respect to the time variable and the classical method of the ordinary differential equations. The inverse Laplace transforms are obtained numerically by using Talbot’s algorithm and the improved Talbot’s algorithm. Numerical results corresponding to a time-exponential pressure gradient and translational motion with the oscillating velocity of the channel walls have been presented in graphical illustrations in order to study the fluid behaviour. It has been found that the ratio of the dielectric constant of fluid layers and the interface zeta potential difference have a significant influence on the fluid velocities.

Accurate modelling of the mechanical behaviour of tendon tissues is vital due to their essential role in the facilitation of joint mobility in humans and animals. This study focuses on the modelling of the supraspinatus tendon which helps to maintain dynamic stability at the glenohumeral joint in humans. It is observed that in sporting activities or careers that involve frequent arm abduction, injuries to this tendon are a common cause of discomfort. Therefore, this paper evaluates the relative modelling capabilities of three hyperelastic models, namely the Yeoh, Ogden and Martins material models on the tensile behaviour of three tendon specimens. We compare their fitting accuracies, convergence rates during optimisation, and the different forms of sensitivities to data-related features and initial parameter estimates. We find that the Martins model outperforms the other models in fitting accuracies; the Yeoh model has the most stable performance across all initial parameter estimates (with correlations above 99 %) and has the fastest convergence rates (above 20 and 8 times as fast as the Ogden and Martins models’ rates, respectively); and that the Ogden model does not depend on differences in the topological features of the test data. The material parameters of relevant constitutive model may be used for further development of computational models.

Due to the limitation that the classical beam theories have in representing transversal shear stress fields, new theories, called high order, have been emerging. In this work, the principal high order theories are unified in single kinematics and applied to the Equivalent Single Layer Theory. The governing equations and the boundary conditions for laminated beams are consistent variational obtained. From the equilibrium equations, the high order spectral finite element model was developed using the polynomial functions of Hermite and Lagrange, with interpolants in the zeros of Lobatto's polynomials. Finally, to demonstrate the finite element model's outstanding efficiency, numerical results (static and dynamic) are shown and compared with the elasticity theory solution

Material properties of a structure can be estimated using destructive and non-destructive methods. Experimental vibration data of the structure can be used to conduct a non-destructive procedure to identify material properties. In this research, experimental modal parameters obtained from modal testing are utilized to estimate the Young’s modulus and the density of different components of a car seat frame. To do so, the finite element model of the structure is constructed and the modal parameters are evaluated by performing modal analysis. The obtained modal parameters are then used in an inverse identification procedure and compared with the experimental counterparts to estimate the material properties of the structure in an optimization framework. The objective function is defined by comparing the numerical and experimental natural frequencies where the material properties are considered as the design parameters of the optimization process. To find the optimum design parameters, the response surface optimization technique is employed to alleviate the computational costs of direct optimization. To this end, the design of experiment method using the Box-Behnken design is conducted to create the design points. The kriging method is then utilized to construct the response surfaces. Finally, the nonlinear programming quadratic Lagrangian method is employed to evaluate the best estimations for the material properties using the response surface optimization method.

Nowadays, the closed die forging process is extensively applied to produce small to medium parts. The parts produced by this method show high strength, impact resistance, and toughness, which is the main advantage of this method compared to casting. Furthermore, the parts produced by this method are considerably close to the final shape of the designed part in terms of appearance compared to the open-die forging process, and the need for secondary operations such as finishing after the subjected process is significantly reduced. The present work investigates the production process with closed die forging of one of the most important parts of the gearbox of Mercedes-Benz 10-wheel truck, which is affected by various mechanical and thermal stresses in its working conditions. Finite element simulation results in ABAQUS software have been applied to analyze experiments for the purpose of evaluating the extent and type of impact of some important process parameters and also compared with the observed practical results. The results indicated that the initial temperature parameter of the workpiece has the highest effect on reducing the flow stress, and consequently, the required maximum force throughout the process. While the other evaluated parameters, i.e., press speed and mold temperature, have a smaller but undeniable impact.

The goal of this work is to study steel-wood-steel (S-W-S) connections in double shear with steel dowels submitted to fire. The design at the ambient temperature was based in Eurocode 5 part 1-1 to determine the number of dowels required based on the connection characteristics. To analyze the influence of these characteristics, connections with dowels diameters with 6, 8, 10 and 12 mm, wood type GL20h, GL24h, GL28h and GL32h and the applied load of 10, 15 and 20 kN were studied. The design at the elevated temperatures was based on the Eurocode 5 part 1-2 and Eurocode 3 part 1-2, to obtain the protection thickness required for fire safety. The protection materials used were the glued laminated timber (Glulam) and type F gypsum plasterboard. The analysis of different parameters and how they influence the connection, was studied clearly using the finite element method. The temperature field allows to determine the char layer in the connections with different wood densities, when unprotected, and compare the protection efficiency with two different types of materials. As conclusion, decreasing the dowels diameter and increasing the applied load, the number of the dowels will increase. With the increasing of the dowel diameters and the wood density, it is possible to observe that the fire capability in the S-W-S connections increases.

In this study, a static and free vibration analysis of single layer FG and sandwich FG plates is carried out using a fifth order shear and normal deformation theory. The displacement field of the present theory includes the terms considering the effect of transverse shear and normal deformation. Also, the terms of the thickness co-ordinate are expanded upto fifth order to predict the accurate bending behavior of the plates. The equations of motion are derived based on Hamilton’s principle, and further solved using Navier’s solution scheme. The present results of displacement, stresses and natural frequencies in sandwich FG plates are obtained and compared with other higher order theories available in literature to check the validity and efficacy of the theory.

In this paper, sandwich plates with flexible core and composite surfaces as well as viscoelastic and auxetic core is investigated under dynamic loading. A new higher order global-local theory is used for simulation of the dynamic behavior of sandwich plate. Ability of simulation the thickness changes of the plate and calculation of exact transverse stresses which are so crucial for studying of thick sandwich plate especially by soft core are some of the important features of the presented theory. Furthermore, in terms of solving equations, an iterative incremental method based on the formulation of transient nonlinear finite element as well as a real time algorithm was employed to simulate viscoelastic behavior accurately. The results indicate a significant increase in the stiffness of the sandwich plate due to the auxetic properties of the core materials, leading consequently to the reduction of the vibration amplitude and stresses level. Some of the innovations belonging to this paper are: 1) presenting a global-local higher-order theory while considering the changes in the thickness of the sandwich plates; 2) calculating transverse stresses using the three-dimensional elasticity method as well as modifying the results obtained from displacement and inertial effects based on this method; 3) simulating sandwich plate with viscoelastic and auxetic cores; 4) taking orthotropic properties for the viscoelastic core into account.

Today, the importance of providing safety and stability while paying attention to the ride comfort and providing road holding is of paramount importance. This issue has become more important due to the many accidents related to vehicle rollover. In this article, an attempt has been made to reduce the risk of rollover prevention of the vehicle while paying attention to the needs of the occupant and the road. In this research, an attempt has been made to reduce the overall acceleration of the GT vehicle by using a series of active variable geometry suspensions and by using a variety of control strategies such as Fuzzy PID, LQR, Sliding mode. In previous works, PID and Skyhook controllers have been used. However, in this study, the choice of the controllers is based on attention to accuracy and optimization while pay attention to control aims. This study was performed in conditions of severe asymmetric roughness and cornering maneuvers. The examination of the results shows an improvement of more than 20% for the goal of vehicle stability while providing other suspension goals. This performance improvement occurs with the effect of suspending variable geometry along with the use of a suitable controller. It should also be noted that the improvement achieved by consuming energy is far less than other suspensions, which is the strength of the research.

In a number of microfluidics-based systems where the Reynolds number is in an intermediate range, both viscosity and inertia are significant, and thus, plenty of interesting effects appear including inertial motion and secondary flow. In recent years, this rapidly expanding area of science has opened a new window of possibilities for micro-particle inertial focusing in high-throughput cellular separation and physiological fluids processing. Moreover, this science is applicable in bio-particle focusing in clinical diagnostics along with widespread applications in environmental cleanup. In this review, fundamental concepts governing the mechanics and physics of inertial microfluidics are discussed. Furthermore, recent mathematical frameworks and theoretical developments that have made this science what we know today are presented in detail. Finally, a number of possible futuristic promising directions in this novel field are proposed since, despite tremendous recent progress, this mainstream technology is still a nascent area of research.