Journal of Applied and Computational Mechanics
Volume:9 Issue: 1, Winter 2023

In this study, the effect of different intake manifold geometries on the performance of a spark-ignited engine is investigated both numerically and experimentally. 1D and 1D-3D simulations are carried out to find the optimal dimensions of different intake manifold designs. The numerical simulations are successfully validated with real data. The results show that the manifold design utilizing two-valve throttle has a better performance. The superior design is constructed and mounted on the engine to compare the output result with the base design. The operation tests are performed at various rotational speeds in the range of 1000-6000 rpm. Regarding the experimental tests, the superior double intake manifold increases the engine brake power and torque by 6.814%.

The exergoeconomics analysis combines thermodynamic assessments based on exergy analysis with economic concepts. this article suggests a new method for exergoeconomics analysis and evaluation of energy systems by considering uncertainty in economic parameters. As the first step, the future values of economic parameters that influence the operating cost of the energy system are forecasted by the Monte Carlo Method. Then, as a novel approach, principles of exergoeconomics analysis method are coupled with the Monte Carlo Method for exergoeconomics evaluation of energy systems. Also, three new parameters, i.e. Risk Factor (RF), Risk Factor Sensitivity (RFS), and Product Cost Sensitivity (PCS), are proposed. Two different approaches are considered in the evaluation process to improve the system: a) decreasing the total cost of products and b) reducing the risk of the cost of products. Also, the proposed method is applied to the CGAM system as a benchmark. Eventually, the results of the first and second approaches show that the total cost of products can be reduced 4.1% (from 22.270 $/GJ to 21.358 $/GJ) and also the risk of the cost of the products can be reduced 5.8% (from 25.8% to 24.3%).

In this paper, post buckling behavior of thin steel and aluminum cylindrical shells with rectangular cutouts under axial loading was studied experimentally and also using the finite element method. Riks method is used for analyzing the cylindrical shells. The effect of longitudinal and circumferential stiffeners (ribs and stringer) was studied on the buckling load and the post buckling behavior as the stiffeners used individually and in combination with each other. It was shown that by adding stringer, the buckling load improves and the rib has a positive effect on the post buckling behavior of the structure. Some tests were performed by ZwickRoell tensile/compression testing machine and it was carried out for both types of steel and aluminum shells with and without stiffeners. Comparing the experimental results with the FEA results shows good agreement. Nonlinear analysis of cylindrical steel and aluminum shells with cutout have demonstrated that, in some cases, a local buckling called snap-back can be seen in the load-displacement path. Snap-back which is a decrease in the amount of both load and displacement indicates this local buckling. This phenomenon is because of appearing mode shapes sequentially during the numerical buckling analysis of shells. Although these local buckling happened, the structure is still endured the higher loads.

In this paper, the influence of equivalence ratio on the low-temperature reaction heat release (LTR-HR) and high-temperature reaction heat release (HTR-HR) of homogeneous charge compression ignition engine has been experimentally and numerically examined. The numerical study was performed using zero-dimensional (0D) single-zone model by considering the chemical kinetic of fuel combustion. Annand, Woschni, Hohenberg, Chang (Assanis), and Hensel semi-empirical heat transfer models were employed in the 0D single-zone simulations. In this study, the in-cylinder pressure, rate of heat release, LTR-HR and HTR-HR were investigated. The Hensel heat transfer model was the only model that predicted the combustion in all of the operating conditions. The Hohenberg model properly recognized the effects of equivalence ratio changes on the HTR-HR.

Inspection and specificity of the intactness of multi-layer and small-size parts like copper-clad steel rod is a hard task and requires high accuracy. The intactness of these parts is crucial due to their importance. One of the inspection methods for these parts is using ultrasonic waves. The scattering phenomenon occurs when these waves impact curved shape bodies under a special condition. The ultrasonic scattering waves contain a lot of information from the physical conditions and mechanical properties of the part. However, using these waves requires high accuracy and attention due to their complexity. One result of the ultrasonic scattering waves is the far-field backscattered frequency spectrum, form function. For the first time in this research, the form function of a copper-clad steel rod that is immersed in water is calculated using the finite element method (FEM) available in the commercial ABAQUS software. For validating the proposed model, the simulation results are compared with analytical and experimental results in the normalized frequency range of 4 £ Ka £ 10. A good agreement is observed between the three methods at the resonance frequencies, and in the overall form of obtained form function. Furthermore, the effects of the two most common defects in these rods, i.e., the corrosion and interfacial disbond between the clad and steel rod, is studied. Results show that this method can properly specify the corrosion percentage and location, and also the length and location of the interfacial disbond defect.

In this research, fourth-order Improved Runge-Kutta method with three stages for solving fuzzy Volterra integro-differential (FVID) equations of the second kind under the concept of generalized Hukuhara differentiability is proposed. The advantage of the proposed method in this study compared with the same order classic Runge-Kutta method is, Improved Runge-Kutta (IRK) method uses a fewer number of stages in each step which causes less computational cost in total. Here, the integral part is approximated by applying the combination of Lagrange interpolation polynomials and Simpson’s rule. The numerical results are compared with some existing methods such as the fourth-order Runge-Kutta (RK) method, variational iteration method (VIM), and homotopy perturbation method (HPM) to prove the efficiency of IRK method. Based on the obtained results, it is clear that the fourth-order Improved Runge-Kutta method with higher accuracy and less number of stages which leads the less computational cost is more efficient than other existing methods for solving FVID equations.

Aeration determines the entrainment of air in another fluid. In geared transmissions, this process affects the operating temperature of the mechanical system because the air’s bubbles trapped in the lubricant act as an insulator. Lubricant’s aeration occurs mainly because the gears’ teeth entering the oil sump and the oil impacting on free surface. Being able to numerically model aeration is fundamental to better describe the physics and the lubrication mechanisms which affect the behavior of the system. In this paper, a new solver that includes the aeration phenomenon was implemented in the opensource environment OpenFOAM®. The simulations’ results were validated with torque measurements. Moreover, a comparison of the oil distribution between a standard multiphase- and the new aeration-solver is provided.

This article is part of the e-cooling project which has been granted by OutoKumpu and Intel. The ‎author has been project manager aiming for optimization of the heat sink application. In this ‎regard, several articles through 2006 to 2012, have been published to explain the chain of the process ‎‎(casting, machining, welding) using the Pin-Fin technology.‎ In 2011 to 2015, The project has been recapped and aiming to develop next design heatsink ‎‎(combined copper- Aluminum heat sink) with special focus for the subsea application. The Risk ‎analyses of the new heat sink design have also been studied. A new model has been developed ‎for industrial production/ optimization process from casting to final processing.‎ The mathematical modeling has been primarily employed to solve the source code addressing the ‎energy of the dissipation rate using the 3D Navier-Stokes equations. The Ansys Fluent has been ‎employed as the modeling software to implement the source term as subroutine. In this industrial ‎research work the implementation of the mathematical modeling in the Ansys Fluent software is ‎a critical part of the work aiming for design and optimization of the heat sink within SCI ‎application‎.

We analyze bifurcation for a cylindrical membrane capable of swelling subjected to combined axial loading and internal pressure. The material is conceptualized as an isotropic and absorbent matrix (it can swell when it is exposed to some swelling agent, for instance) containing nonabsorbing fibers. More in particular, fibers are symmetrically arranged in two helically distributed families which are (also) mechanically equivalent. Arterial wall tissue has been modeled using this theoretical framework. The matrix of the membrane is taken to be a swellable neo-Hookean material. The swollen membrane is then inflated and axially stretched so that the circular cylindrical geometry is initially preserved. Nevertheless, prismatic, bulging, and bending (composite) bifurcation conditions are analyzed. It is shown that for membranes with and without fibers, prismatic bifurcation does not play a major role. On the other hand, bending and bulging are feasible for fiber-reinforced membranes. Results capture the onset of bifurcation configurations corresponding to bending and bulging and highlight possible coupling during postbifurcation as it might occur, for example, in the formation and development of an abdominal aortic aneurysm.

In this paper, a new strategy for developing effective control policies suitable for guiding the motion of articulated mechanical systems that are described within the framework of multibody system dynamics is proposed. In particular, a scissor lift table having a pantograph topology is analytically modeled as a rigid multibody system by using a Lagrangian formulation. An operational approach is thus introduced in this investigation to design the control system that commands the motion of the lift table. In this vein, two dynamical models are developed in this investigation, namely a minimal coordinate multibody model and a redundant coordinate multibody model. While the minimal coordinate multibody model is used in the paper for the optimal design of a high-performing nonlinear controller, the redundant coordinate multibody model is employed to verify both the efficiency and the effectiveness of the control approach adopted in this work. More specifically, the nonlinear control system devised in this paper is based on the combination of an open-loop control architecture with a closed-loop control strategy. The open-loop control policy is determined by using a nonlinear quasi-static feedforward controller, whereas the closed-loop control action is obtained considering an error-based proportional-derivative feedback controller. With the use of both the pantograph scissor lift multibody models developed in this work, several numerical experiments are carried out in the paper, thereby demonstrating the readiness and the effectiveness of the control methodology proposed in this investigation.

The article describes the problem of unsteady vibrations of a Bernoulli-Euler beam taking into account the relaxation of temperature and diffusion processes. The initial mathematical model includes a system of equations for unsteady bending vibrations of the beam with consideration of heat and mass transfer. This model is obtained from the general model of thermomechanodiffusion for continuum using the D'Alembert's variational principle. The solution of the problem is obtained in the integral form. The kernels of the integral representations are Green's functions. For finding of Green's functions the expansion into trigonometric Fourier series and Laplace transform in time are used. The calculation example is investigated for a freely supported three-component beam made of zinc, copper and aluminum alloy under the action of unsteady bending moments, including the interaction of mechanical, temperature and diffusion fields.

This work presents a simplified methodology for coupling the physics of a nanosecond-pulsed discharge to the process of supersonic combustion within a backward-facing step combustor. The phenomena of plasma and supersonic combustion are simulated separately and then coupled. Based on results reported in the literature, a zero-dimensional plasma model is built, considering only the kinetic effects of the nanosecond-pulsed discharge. A set of Favre-averaged compressible Navier-Stokes equations, as well as finite rate chemistry, is used in the combustion model and solved with a control-volume based technique. The plasma-supersonic combustion coupling process only considers the discharge as a source of O and H radical species. The calculated densities of the radicals generated during each pulse from the plasma model are periodically seeded inside the domain of the combustor. The proposed methodology is used to perform a novel simulation that involved the application of plasma to a well-known supersonic combustion experiment. The temperature and species concentration contours show that the proposed methodology captures the main effects of the nanosecond-pulsed discharge on supersonic combustion. The ignition delay time is reduced when the plasma discharge was applied. In addition, the simulations show that the plasma causes a supersonic low-enthalpy mixture to ignite, confirming the capability of the methodology.

The filling of a plane gap with a non-Newtonian fluid under non-isothermal conditions is considered by assuming viscous dissipation and curing reaction induced by the heat supplied through the walls of the gap. The rheology of the medium is described by the modified Cross-WLF model accounting for the effect of temperature, strain rate intensity, and the extent of a chemical reaction on the viscosity. The curing reaction kinetics is determined by the equation based on the n-th order reaction with self-acceleration. The problem is solved numerically using an original computational technique. The curable fluid flow structure is revealed to include three characteristic zones during the filling process: a fixed layer on the solid wall with a high degree of curing; a central “core” with an almost uniform distribution of characteristics; and a transition zone serving as a "lubricating" layer between two abovementioned zones. The structure is governed by heating of the fluid through the wall, since the heating affects the rheological characteristics of the medium and the rate of the cured layer formation. Analysis of the similarity criteria for the considered flow conditions shows that the fluid flows in a creeping regime (Re < 0.01); the temperature distribution is mainly affected by convective heat transfer (Pe > 100); the influence of dissipative heating and exothermic effect of the curing reaction is insignificant. The effect of curing on the mass distribution of the liquid portions entering through the inlet section is shown. The variation of the pressure distribution is analyzed at various flow conditions.

The empirical Power Law model has a long usage history in cable self-damping studies, and several types of research have been done to characterize its parameters for various types of cables. In this work, a novel Bayesian model calibration framework is proposed and applied to study self-damping Optical Ground Wire (OPGW) cables. This technique then combines experimental and statistical approaches to obtain the confidence intervals for each parameter and characterize the different regions where the model presents other behaviors. The results enable a better calibration of the model's parameters and agree with the trends already set in the literature. They also provide a new understanding of the model and estimate different uncertainties its application entices.

This paper presents an optimal design of a sweep blade for the axial wind turbine using a hybrid surrogate-assisted optimizer. The design problem is defined to maximize the ratio of the torque coefficient to the thrust coefficient of a turbine blade at a low wind velocity of 10 m/s. Pitch angle and leading-edge blade curve are considered as the design variables. For the aerodynamic analysis of the wind turbine blade, computational fluid dynamics has been used as a high-fidelity simulation. While the surrogate models including, the Kriging model (KG), the radial basis function model (RBF), and the proposed hybrid of KG and RBF (HyKG-RBF) models are applied for function approximation or low-fidelity simulation. In this study, to obtain a set of sampling points and surrogate models development, an optimal Latin Hypercube sampling (OLHS) technique is utilized in the design of the experiment (DOE). A differential evolutionary (DE) algorithm is used to solve the proposed design problem. The performance of the proposed hybrid surrogate assisted optimization method is contrasted with two conventional surrogate assisted optimization techniques. Results demonstrate that the proposed hybrid surrogate model viz. HyKG-RBF is the most efficient surrogate-assisted optimization method for solving the sweep blade optimization problem.

Continuity and discontinuity of two-dimensional domains are thoroughly investigated for accuracy and convergence rate using two prominent discretization methods, namely smoothed and scaled boundary finite element. Because of their capability and versatility when compared to primitive elements, N-sided polygonal elements discretized from modified DistMesh and PolyMesher schemes are used. In terms of accuracy and convergence rate, NSFEM and SBFEM are found to be superior to CSFEM and ESFEM regardless of meshing alternative. The best accuracy occurs at NSFEM and SBFEM, and the obtained convergence rates are optimal. Particularly, in the smoothing domain, it is believed that DistMesh has more promising potential than PolyMesher does; yet, in the discontinuity domain, PolyMesher has been discovered to be more powerful while maintaining its efficiency.

This article develops a mathematical model to study the static stability of bi-directional functionally graded porous unified plate (BDFGPUP) resting on elastic foundation. The power function distribution is proposed for the gradation of material constituent through thickness and axial directions. Three types of porosity are selected to portray the distribution of voids and cavities through the thickness of the plate. Unified theories of plate are exploited to present the kinematic fields and satisfy the zero-shear strain/stress at the top and bottom surfaces without shear correction factor. Hamilton’s principle is employed to derive the governing equations of motions including the higher terms of force resultants. An efficient numerical method namely differential integral quadrature method (DIQM) is manipulated to discretize the structure spatial domain and transform the coupled variable coefficients partial differential equations to a system of algebraic equations. Problem validation and verification have been proven with previous works for bucking phenomenon. Parametric studies are exemplified to exhibit the significant impacts of kinematic shear relations, gradation indices, porosity type, and boundary conditions on the static stability and buckling loads of BDFGP plate. The proposed model is economical in different applications in nuclear, mechanical, aerospace, naval, dental and medical fields.

The inverse finite element method (iFEM) is an efficient algorithm developed for real-time monitoring of structures equipped by a network of strain sensors. The inverse element for modeling curved beams was previously developed using an approximate solution based on independently interpolated displacement components. In this study, a new formulation is proposed by the development of a least-squares variational principle using the kinematic framework of the curved beam theory. The library of existing iFEM-based elements is expanded by introducing three different inverse curved elements named iCB3, iCB4 and iCB5 respectively. This new formulation has been developed considering the exact solution of the curved beam theory that corresponds to the membrane-bending coupling and the explicit statement of the rigid-body motions. The three inverse elements, which require three, four and five measurement points respectively, extend the practical utility of iFEM for shape sensing analysis of curved structures according to the minimum available quantity of strain sensors. The effectiveness and higher accuracy of the iCB/iFEM methodology compared to other solutions present in literature are demonstrated considering numerical studies on curved beams under static transverse force and distributed loading conditions. For these problems, the effect of strain measurements error, number of sensors and discretization refinement on the solution accuracy is evaluated.

The joint impacts of electro-osmotic, variable viscosity, magnetic field, chemical reaction, and porosity on blood flow in the artery slant from the axis at an angle with mild stenosis are investigated using Yang transform homotopy perturbation method (YTHPM). The mathematical model, solved by Tripathi and Sharma, is developed by adding the effect of electro-osmosis. The results of axial velocity, concentration, temperature, and the wall shear stress for blood flow are studied in two cases, the absence and presence of electro-osmosis. The results illustrate that an increase in the electro-osmotic parameter and Helmholtz Smoluchowski velocity leads to velocity increases, while the temperature increases when the Joule heating increases with constant values of electro-osmotic parameter and Helmholtz Smoluchowski velocity. On the contrary, it is noted that the electro-osmotic on concentration has no significant effect. Moreover, the importance of applying electro-osmotic is exhibited through proper use and explaining that how it can benefit physicians during surgical operations. Furthermore, a contour plot is created to show the difference in the profile of velocity to the flow of blood when the magnetic field is increased and the altitude of stenosis takes the larger values. The results exhibit that YTHPM is effective in finding the analytical approximate solutions for Newtonian blood flow under the electro-osmotic parameter influence, with good convergence. In addition, the new solutions' graphs demonstrate the truthfulness, utility, and exigency of YTHPM which are in excellent agreement with the results of earlier investigations.

The present work aims at generating a systematic way for longitudinal vibration (LV) analysis of bars (or rods) with arbitrary boundary conditions (BCs) by mixed-type finite element (MFE) method using the Gâteaux differential. Both materials and geometrical properties of the bar are uniform along the longitudinal direction. The problem is reduced to solution of the classical eigenvalue problem in dynamic analysis. The axial (normal) load and the displacement along the bar are the basic unknowns of the mixed element. The element formulation for the shape function must satisfy only C0 class continuity since the first derivatives of the variables exist in the functional. The functional governed with proper dynamic and geometric BCs of the problem. Results of the recommended method are benchmarked and verified via numerous problems present in the literature. The unique aspects of this study and the possible contributions of the proposed method to the literature can be summarized as follows: by using this new functional, displacements and internal force values can be obtained directly without any mathematical operation. In addition, geometric and dynamic BCs can be obtained easily and a field variable can be included to the functional systematically. To examine the effects of BCs on the longitudinal vibratory motion of a uniform elastic bar and to give a better insight into LV analysis of bars with arbitrary BCs, a set of numerical examples are presented.