Fiber metal laminates (FMLs) are high-performance hybrid structures based on alternating stacked arrangements of fiber-reinforced plastic (FRP) plies and metal alloy layers. In this paper, effect of some geometrical and material parameters on free vibrations of FML plates was studied. The first-order shear deformation theory (FSDT) as well as the Fourier series method was used to analytically solve the governing equations of the composite plate. The accuracy of the used method was verified by comparing the Rayleigh-Ritz analytical method and the ABAQUS finite element software (numerical) method. The results indicated that some of the important parameters like sequence of metal layers, aspect ratio (a/b) of plate and orientation of composite fibers were important factors affecting free vibration of the FMLs.

This paper considers the effect of the damage caused by transverse stresses due to a low velocity impact loading on composite plates. The dynamic response of a plate is calculated using the modal superposition technique based on the classical plate theory of sandwich plates (stratified) taking into account transverse shear effects. An indentation law, based on the Hertz theory and verified experimentally, governs the behavior of the plate subsequent to impact. The numerical time integration scheme is used to calculate the contact force at any instant by combining the indentation and the dynamic response of the structure. The obtained results show a good correlation between the shock results and their prediction. This method is equally applied to the contact force as well as to the deformation of the plate. The simulation permits a parametric study of the structure dimensions and the material properties on the global behavior of the plate.

The study aims at examining the behaviour of electromagnetic actuator as inductive sensor. The electromagnets are integrated in an alternative Wheatstone bridge and powered with alternative tension. This circuit allows the measurement of the electromagnet inductance variation, and as this variation is a function of the air gap, the displacement can be deduced. The effect of eddy currents is assessed in order to choose the suitable bridge frequency. Finally, a demodulator is used to obtain the tension proportional to the air gap value. The behaviour is assessed experimentally. Experiments are carried out on a simple beam; clamped at one end and simply supported at the other. The displacements could be measured by using four eddy current sensors and the inductive sensor. The inductive sensor displacement and a modal approximation of the four eddy current sensors resulting from impact testing are compared. Analysis of the results obtained predicts an efficient and robust behaviour.

In this study, vibration of helical compression springs, excited axially, is discussed. The mathematical formulation of the dynamic behavior of the springs is composed of a system of four partial differential equations of first order hyperbolic type, which are the equations of momentum and the laws of constitution. The principle unknown variables are angular and axial deformations and velocities. In small deformations, the coefficients of the equation system are constant and the model describes the linear dynamic behavior of coil springs. The impedance method is applied to calculate the frequency spectrum and to study the natural frequency response. The study takes into account the dynamic coupling between the axial and angular waves due to the effects of Poisson’s ratio. The results show two fundamental frequencies corresponding to the two wave speeds: fast angular waves and slow axial waves. The numerical resolution is performed by the conservative finite difference scheme of Lax-Wendroff and the finite element method. The results were used to analyze the evolution in time of deformations and velocities in different sections of the spring due to a sinusoidal excitation of the axial velocity applied at the end of the spring and to show the effect of the interaction between the axial and angular waves. These results clearly show the resonance and other phenomena related to wave propagations such as wave reflections and beat.

Large thrust bearings are highly loaded machine elements and their failures cause serious losses. Start ups and stoppages of the bearing under load are specially critical regimes of operation. Load carrying capacity depends on the profile of the oil gap. In transient states this profile is also changing. In the design of large thrust bearings minimizing thermo-elastic deformations is an important goal, which can be accomplished due to application of advanced models of the bearing. Modeling of transient states becomes even more complex since there is a dynamic development of temperature distribution and deformations. Often hydrostatic jacking systems are also used. It seems to the authors that advanced bearing models are applied only in research and development of the bearings while very simple modeling is applied in on-line analysis of data from monitoring systems. Analysis of the measurement data with the use of more sophisticated models may be helpful in assessment of current bearing status – especially in early warning. Material issues create a separate problem for modeling, being more important nowadays as polymer lined bearings come into use. The models used for polymer lined bearings require realistic treatment of heat exchange and resilience of the bearing surface layer.

This paper presents a numerical study about lubricant inertia effect on thermohydrodynamic (THD) characteristics of Rayleigh step bearings running under steady, incompressible and laminar condition. To reach this goal, the set of governing equations is solved numerically with and without considering the inertia terms. The discretized forms of the momentum and energy equations are obtained by the finite volume method and solved using the Computational Fluid Dynamic (CFD) technique. These equations are solved simultaneously because the dependency of lubricant viscosity with temperature. The hydrodynamic and thermal behaviors of the slider step bearings are demonstrated by presenting several figures including the lubricant pressure and temperature distributions with and without considering the fluid inertia effect. Numerical results show that inertia term has considerable effect on THD characteristics of step bearings, especially when they run with high velocity of runner surface.

In the present paper an experimental investigation of drag reduction on in-line tube bundles with a configuration of seven by seven with a pitch ratio of 1.44 has been performed. Two longitudinal grooves are placed on the external surface of the circular cylinders as a passive control. The experiment is carried out using a subsonic wind tunnel. The pressure distributions for various azimuthal angles along the tubes are measured using a multi-channel differential pressure. Drag forces are also determined using a combined wire-strain gauge balance. The pressure drops are deduced from the resulting drag forces. The results obtained show an unexpected reduction in the pressure drop for the tube bundles. A reduction of 36.5% in the pressure drop for a Reynolds number of 1.33 × 104 is found compared to the configuration without grooves. Some correlations for the pressure drop are proposed.

The study of the phenomenon of cavitation of centrifugal pumps remains of a great importance in the field of construction as well as in the field of installation of pumps in pumping stations. In fact, with the consequences it engenders: noise, vibration, erosion and loss of efficiency, it provokes, on the one hand, a progressive degradation of the performance of the machine and, on the other hand, an increase in the costs of the maintenance of installation (a compromise between the functioning period and cost of exploitation), in addition to the loss of efficiency of pumps and the resistance of different materials to the effects of the phenomenon of cavitation. Among the techniques and methods of protecting the parts of pumps is the cladding of the parts with composite plastic materials for the purpose of increasing the resistibility and protecting the parts from the effects of cavitation. Relevant to this, our work aims at analysing this problem with the intention of preserving the efficiency of a pump by limiting the effects of cavitation through an experimental study that has been realized in a laboratory. As such, wheels of different materials are tested under conditions of cavitation taking into consideration the three types of metals used in the manufacture of the wheel, and this regarding the study of resistibility of each material subject to the effects of the phenomenon aforementioned. Thus, this present work consists in experimentally studying the physical impact of cavitational erosion upon the hydrodynamic behavior and the performances of centrifugal pumps, and that affects the weight of different wheels. This phenomenon can be obtained only through measurement: loss of efficiency that can have repercussions for the characteristics of functioning as well as the mechanical behavior.

Heat transfer during agitation of Bingham viscoplastic fluid is studied in this paper. The fluid is agitated with an anchor impeller and the heating is made by a jacketed wall of the stirred vessel. Transfers in the agitated vessel, translating hydrodynamic and thermal phenomena, are numerically predicted by means of Computational Fluid Dynamics (CFD) in transient regime. The purpose of this numerical study is to identify the rigid zones and to optimize mixing and heating performances. The Navier-Stokes and energy equations are discretized using finite volume method, and a two-dimensional analysis of the hydrodynamic and transient thermal behaviours generated in the agitated vessel are performed. Fluid rheology is modeled by the Bingham approximation and Papanastasiou’s regularization model. Results show the presence of recirculation zones and permit to explain the unpredicted Nusselt number increasing when Oldroyd number increases. This study shows also the importance of the anchor position on the size and the shape of the rigid zones and on the heating performances.

For using the swirling jet for air conditioning and heating in the premises, knowledge of the thermal characteristics is more than necessary. It is for this objective that the experimental and numerical study was realized. To conduct this study, we designed and built an experimental facility to ensure proper conditions of confinement in which we placed five air blowing devices with adjustable vanes, providing multiple swirling turbulent jet with a swirl number S = 0.4. The jets were issued in the same direction and the same spacing defined between them. This study concerned the numerical simulation of the thermal mixing of confined swirling multi-jets, and examined the influence of important parameters of a swirl diffuser system on the performance characteristics. The experimental measurements are also realized for a confined domain, aiming to determine the axial and radial temperature field. The CFD investigations are carried out by an unstructured mesh to discretize the computational domain. In this work, the simulations have been performed using the finite volume method and FLUENT solver, in which the standard k-ε, K-ε realizable, k-ε RNG and the RSM turbulence model were used for turbulence computations. The validation shows that the K-ε RNG model can be used to simulate this case successfully.