Knowing the stresses and pressures in the contact between two deformable solids is fundamental in order to optimize the strength and the lifetime of mechanical components such as bearings or gears. These constraints can be determined by the calculation (finite element method or Hertz theory) or by experimental methods such as photoelasticity. The objective of this study is to model and compute the stress field and contact pressure using 3D finite element software. The validation of obtained results is done by comparison with the classical results of the non linear Hertz theory between two deformable cylinders. An application to spur gears with a circle involute profile is done and also validate with the same

The objective of the present study is the active flow control of blood in the aorta with atherosclerosis using an External Magnetic Field (EMF) in order to facilitate the blood flow. For that purpose, a numerical investigation has been developed with a Magneto-hydrodynamics flow modelisation. The blood is considered homogeneous, incompressible and Newtonian and the fluid flow is assumed to be unsteady, two-dimensional and laminar. The aorta tissue is electrically conductive. Fluent software has been used to solve the governing equations. The results relating to velocity, pressure and the wall shear stress indicate that the presence of the EMF considerably influences the blood flow. The flow control deals with the effects of the EMF direction of application and its intensity. The results show that by applying an EMF, the blood velocity and pressure in the aorta are entirely affected. The direction and the intensity of the EMF allow minimization of the flow instabilities due to the geometrical singularities. Therefore, applying an EMF can be considered an appropriate method for flow control in order to obtain a uniform blood circulation around the atherosclerosis.

The objective of this work is the development of a Fe-W-Ni sintered steel obtained by the powder metallurgy technique. The latter is widely used today for the design of new alloys based on powders (iron) to meet industrial requirements in strength and wear characteristics. The proposed alloy is based on iron mixed with 5% nickel and various percentages (5, 10, 15 and 20%) of tungsten. The effect of the tungsten W content on mechanical and structural properties is presented.

The energy balance components of a greenhouse as well as the greenhouse design may strongly impact the greenhouse energy. Few studies were devoted to the description of the energy balance components of a greenhouse located in the semi arid region of the southern Mediterranean basin, and no attention was paid to the prediction of the inside air temperature. In this study, experiments were undertaken to investigate the response of a greenhouse to the outside climate conditions considering a naturally ventilated Venlo glasshouse with a tomato crop. The measurements show that the difference between inside and outside air temperature is strongly linked to the incoming solar radiation as well as to the wind speed. From these results a simplified model was established to predict the greenhouse air temperature, knowing the greenhouse characteristics and the outside climate variables. The model is based on the energy balance of the greenhouse. Using a parameter identification technique, the model was calibrated against the experimental results. A sensivity analysis was conducted to assess the impact of several physical parameters such as solar radiation, wind speed and cover transmission on the evolution of the inside air temperature. This model appears to be suitable for predicting the greenhouse air temperature satisfactorily.

The purpose of this study was to establish a method based on an iterative scheme to approximate the numerical solution obtained from finite elements analysis for an RVE in two and three dimensions based on the homogenization concept for the assessment of the effective properties. The bounds of Hashin–Shtrikman and Voigt–Reuss were considered in the iterative process based on an updating of the constitutive relations of these models respectively. In this study, by assumption, we took the particular case of the heterogeneous materials with several elastic isotopic phases. The output variables considered using the iterative process are the bulk, shear modulus and the thermal conductivity. We have found a fast convergence of the iterative solution to the numerical result with a suitable concordance between the two solutions at the final step.

In the present work, (Cu-Sn, Cu-Co) based alloys with different compositions have been obtained by using powder metallurgy (PM). These alloys were created with the purpose of increasing mechanical and structural properties of the industrial parts. The compacts are made according to the sintering manufacturing method, the uniaxial compressed cold samples. Metallographic characterizations, hardness and density measurements were carried out in order to study the influence of the addition of tin and cobalt, the variation of the compaction pressure and the sintering temperature on the finishing product. It has been proved that the addition of tin and cobalt to a copper powder mixture increase the properties of the sintered parts.

In the present work, Fe-Cu based alloys with different compositions have been obtained by using Powder metallurgy (PM). These alloys were created with the purpose of increasing mechanical properties of the parts. Nevertheless, little have been published, once this is a matter of industrial interest. In this work, samples of Fe_100-x Cu_x (x=0.40, 0.55, 0.70, 0.85 and 1) alloys were processed by cold pressing at 10 MPa, followed by sintering at 1250 C°. Structures formed during sintering were studied by EDS. Microstructural aspects were observed by MEB. Densification and microhardness tests were also performed.

The purpose of this study was to establish a method based on an iterative scheme to approximate the numerical solution obtained from finite elements analysis for an RVE in two and three dimensions based on the homogenization concept for the assessment of the effective properties. The bounds of Hashin–Shtrikman and Voigt–Reuss were considered in the iterative process based on an updating of the constitutive relations of these models respectively. In this study, by assumption, we took the particular case of the heterogeneous materials with several elastic isotopic phases. The output variables considered using the iterative process are the bulk, shear modulus and the thermal conductivity. We have found a fast convergence of the iterative solution to the numerical result with a suitable concordance between the two solutions at the final step.

Sun-tracking system is a key factor for solar photovoltaic (PV) future and new answers for the solar market. It will expand large scale PV-projects (PV farms) worldwide, and it is possible to collect more energy from the sun. PV farms consist of thousands of sun-tracking systems (STS) that are subject to dynamic loads (wind, snow, etc.), vibration, and gravitational loads. This paper presents the structural dynamic analysis of a 24 m² bi-axial sun-tracking system (azimuth-elevation) at different elevation angles based on its modal parameters (natural frequencies, modal shapes and modal damping ratios) and dynamic performance indices (Modal participation factors, forcing frequencies and mechanical quality factors) by means of the Finite Element Analysis (FEA). The simulation results show that the structural dynamic design of the STS meets the desired structural requirements and agrees well with structural dynamic standards (EN 1991-1-4 and ASHRAE). These results can be used for further analysis on optimal design and vibration safety verification for the bi-axial sun tracking systems (PV applications).
Structural Dynamics Analysis of Three-Dimensional Bi-Axial Sun-Tracking System Structure Determined by Numerical Modal Analysis | Request PDF. Available from: https://www.researchgate.net/publication/323002148_Structural_Dynamics_Analysis_of_Three-Dimensional_Bi-Axial_Sun-Tracking_System_Structure_Determined_by_Numerical_Modal_Analysis [accessed Oct 31 2018].

In the present work, Fe-Cu based alloys with different compositions have been obtained by using Powder metallurgy (PM). These alloys were created with the purpose of increasing mechanical properties of the parts. Nevertheless, little have been published, once this is a matter of industrial interest. In this work, samples of Fe_100-x Cu_x (x=0.40, 0.55, 0.70, 0.85 and 1) alloys were processed by cold pressing at 10 MPa, followed by sintering at 1250 C°. Structures formed during sintering were studied by EDS. Microstructural aspects were observed by MEB. Densification and microhardness tests were also performed.