Influence of B4C and industrial waste fly ash reinforcement particles on the micro structural characteristics and mechanical behavior of aluminium (Al–Mg–Si-T6) hybrid metal matrix composite

The expectations over composite materials have been increased especially in automotive and aerospace applications due to its high strength to weight ratio and good mechanical properties. Here, we aim to fabricate a hybrid composite of high strength and low density for automotive application to suits the above needs. In this investigation, the heat-treated aluminum alloy Al–Mg–Si-T6 was initially reinforced with industrial waste fly ash particles at five different weight fractions of 0%, 5%, 10%, 15% and 20%, respectively by stir casting process. The mechanical properties such as tensile strength, compression strength, hardness and density were tested, and microstructure of the composite was evaluated to explain the mechanical properties evolution. From the results, it was concluded that the composite with 10% fly ash shows enhanced at maximum the properties when compared to others. Then, the Al–Mg–Si-T6 – 5% fly ash was further reinforced with boron carbide particles by using three different fractions of 2.5%, 5% and 7.5%, respectively by stir casting process. The microstructural analysis, Scanning Electron Microscope analysis (SEM) and Energy Dispersive X-ray Spectroscopy analysis (EDS) were carried out for the casted samples to evaluate interfacial bonding, agglomeration, clustering and void formation in the hybrid composite samples. The casted samples were also tested for mechanical properties such as tensile strength, compression strength, hardness and density. It reveals that the optimal combination of 10% reinforcement (5% fly ash and 5% boron carbide) shows 18.7% higher tensile strength, 11.3% higher hardness and 38.6% higher compression when compared with the unreinforced Al–Mg–Si-T6 heat treated alloy. It is expected that the present hybrid metal matrix composites can be adopted for the fabrication of drive shaft in race cars

Mathematical Modeling and Simulation in Mechanics and Dynamic Systems

Although it has previously been considered difficult to make further contributions in the field of mechanics, the spectacular evolution of technology and numerical calculation techniques has caused this opinion to be reconsidered and to the development of more and more sophisticated models that describe, as accurately as possible, the phenomena that take place in dynamic systems [...

Mathematical Modeling and Simulation in Mechanics and Dynamic Systems

Although it has previously been considered difficult to make further contributions in the field of mechanics, the spectacular evolution of technology and numerical calculation techniques has caused this opinion to be reconsidered and to the development of more and more sophisticated models that describe, as accurately as possible, the phenomena that take place in dynamic systems [...

Dynamic Absorption of Vibration in a Multi Degree of Freedom Elastic System

The paper aims to identify the situations in which a complex elastic system, which is subject to mechanical vibrations, can act as a dynamic absorber of vibrations for certain frequencies. The conditions that the system must fulfill in order to achieve this goal are determined and then a calculation example is presented. The method is interesting because it allows to avoid attaching an absorber specially built for this, a situation that complicates the project and increases manufacturing costs

Dynamic Absorption of Vibration in a Multi Degree of Freedom Elastic System

The paper aims to identify the situations in which a complex elastic system, which is subject to mechanical vibrations, can act as a dynamic absorber of vibrations for certain frequencies. The conditions that the system must fulfill in order to achieve this goal are determined and then a calculation example is presented. The method is interesting because it allows to avoid attaching an absorber specially built for this, a situation that complicates the project and increases manufacturing costs

On the Accuracy of Turbulence Model Simulations of the Exhaust Manifold

This study investigating the accuracy of turbulence model simulations of the exhaust manifold using computational fluid dynamics (CFD) carries significant implications. By modeling and analyzing the flow of emissions, we aim to identify areas of high stress and pressure, minimize the pressure drop, and maximize the flow of exhaust gases. This not only enhances engine performance, reduces emissions, and improves the durability of the manifold but also provides a unique opportunity to predict and analyze the flow and performance of the exhaust manifold, both quantitatively and qualitatively. This paper aims to provide a detailed comparison of five turbulence models that are commonly used in CFD to offer valuable insights into their accuracy and reliability in predicting the flow characteristics of exhaust gases. The results show that the k-kl-ω model showed the highest maximum velocity and the most comprehensive temperature range, efficiently capturing the transitional flow effects. The K-ω STD and SST transition models displayed significantly higher turbulent kinetic energy (TKE) values, indicating their enhanced effectiveness in modeling complex turbulent and transitional flows. Conversely, the Reynolds stress and RNG k-epsilon models displayed lower TKE values, suggesting more subdued turbulence predictions. Despite this, all models exhibited similar pressure drop trends, with a noticeable increase near the midpoint of the manifold. These quantitative findings provide valuable insights into the suitability of different turbulence models for optimizing exhaust manifold design

Modelling the Valvetrain of the Car Engine to Study the Effects of Valve Rotation

The valve performs an alternating translational motion along its axis of symmetry, which is accompanied by a rotation about its own axis, possibly due the valve body’s cylindrical geometry and due to the conjugate element, the guide, which is also a cylindrically shape body. By ensuring this rotational motion of the valve, a number of advantages are obtained, mainly related to the increase of the operating period of the valve and implicitly of the engine. Following the critical analysis of the current state of research on the valvetrain systems and the rotational motion of the valves, the advantages and the disadvantages of valve rotation during engine operation were established. To this end, it has been established that, in addition to the theoretical approach to the problem, it is necessary to create a virtual model of the valvetrain mechanism to do a thorough analysis of the problem. Based on the model, the influence of the camshaft speed, temperature and lubricating oil pressure were monitored by changing the coefficient of friction, the influence of the cam position relative to the tappet and the influence of the valve spring. In this paper, the authors want to determine the rotational motion characteristics of internal combustion engine valves and to suggest measures that can be taken to ensure valve rotation at all operating modes without the use of auxiliary devices for generating rotational motion

Vibration Response of a Concrete Structure with Repetitive Parts Used in Civil Engineering

The paper studies the vibration behavior of a concrete structure, currently used in civil engineering. The truss structure considered has symmetries that can be used to facilitate both the design and construction of the building. Moreover, the symmetries encountered can be used to simplify the calculation of vibrations of the system. Based on the mechanical model built, eigenvalues and eigenvectors of such mechanical system are determined, and properties, specific to these symmetries, are identified. In this way, the dynamic analysis of the structure can be simplified and also, the design as well as the costs related to this stage

Modelling the Valvetrain of the Car Engine to Study the Effects of Valve Rotation

The valve performs an alternating translational motion along its axis of symmetry, which is accompanied by a rotation about its own axis, possibly due the valve body’s cylindrical geometry and due to the conjugate element, the guide, which is also a cylindrically shape body. By ensuring this rotational motion of the valve, a number of advantages are obtained, mainly related to the increase of the operating period of the valve and implicitly of the engine. Following the critical analysis of the current state of research on the valvetrain systems and the rotational motion of the valves, the advantages and the disadvantages of valve rotation during engine operation were established. To this end, it has been established that, in addition to the theoretical approach to the problem, it is necessary to create a virtual model of the valvetrain mechanism to do a thorough analysis of the problem. Based on the model, the influence of the camshaft speed, temperature and lubricating oil pressure were monitored by changing the coefficient of friction, the influence of the cam position relative to the tappet and the influence of the valve spring. In this paper, the authors want to determine the rotational motion characteristics of internal combustion engine valves and to suggest measures that can be taken to ensure valve rotation at all operating modes without the use of auxiliary devices for generating rotational motion

Calculation of Homogenized Mechanical Coefficients of Fiber-Reinforced Composite Using Finite Element Method

Determining the mechanical properties of a composite material represents an important stage in its design and is generally a complicated operation. These values are influenced by the topology and geometry of the resulting composite and the values of the elastic constants of the components. Due to the importance of this subject and the increasing use of composite materials, different calculation methods have been developed over the last fifty years. Some of the methods are theoretical, with results that are difficult to apply in practice due to difficulties related to numerical calculation. In the current paper, using theoretical results offered by the homogenization theory, values of engineering elastic constants are obtained. The finite element method (FEM) is used to determine the stress and strain field required in these calculations; this is an extremely powerful and verified calculation tool for the case of a material with any type of structure and geometry. In order to minimize errors, the paper proposes the method of least squares, a mathematical method that provides the best estimate for the set of values obtained by calculating FEM. It is useful to consider as many load cases as possible to obtain the best estimates. The elastic constants for a transversely isotropic material (composite reinforced with cylindrical fibers) are thus determined for a real case