In the ethics of any campaign for the promotion and popularization of an innovative material, it is necessary to pass it through all the standardized tests in order to classify it. To do this, we propose in this investigation the characterization of a sandwich structure whose two skins are made of composites and in the presence of a transverse structural element in the form of a seam. The vibrational method for characterizing innovative materials is expressed by analyzing the self-response spectrum of a standardized specimen excited by an impulsive walking effort. Its particularity of being a non-destructive characterization test makes it essential in the case of innovative materials because their first manufacture is always expensive. In the present study, the fabric of the structure is a sandwich plate sewn by rovings which consolidates the connection between the two skins and the core while ensuring transverse rigidity to the sandwich. The open end was censored by a vise while fixing the signal sensor to the other free end. The acquisition of the results was managed by the PULSE software and an analyzer based on the fast Fourier transformations (FFT). Compared to its analogues in the specialized literature, our experience gave very effective results, and the test piece remained solid and susceptible to further destructive tests for confirmation. However, our sandwich plate is distinguished by its complete composition in composite both the two skins and the seam rovings, for the filling of the core it is ensured by a constructive foam which in principle plays no structural role.

Knowing the effective of both mechanical and thermal properties of composite materials allows researchers to improve their behavior and increasing its reliability. In this study, a simplified micromechanical approach is used to modelling and analysis the unidirectional carbon-fiber/epoxy composite performances. The principle objective of this work is to evaluate the effect of the fiber geometrical configurations on the effective mechanical properties and the thermal expansion’s coefficients considering three different geometrical configuration of the fiber. Hence, the unidirectional composite with ellipsoidal fiber is stiffer than others with cylindrical or parallelepipedal fibers. Moreover, the considered configuration wherein the fiber has an ellipsoidal shape leads to lower effective coefficients of thermal expansion corresponding to more cohesion between particles.

Electric vehicles and renewable energy are currently viewed as completely complementary clean energy technologies. In this paper, a renewable energy management system based on a hybrid smart vehicle is used, combining the energy from the fuel cell and the energy from the storage devices according to the driving cycle response and long-distance autonomy. Thus, the use of fuel cells and storage batteries in the automotive sector is expected to play a major role in addressing the issue of sustainable mobility in the long run. In a hybrid vehicle, the electrical motor is hopped-up by a electric cell aided by a secondary energy supply. The latter is either a battery or a supercapacitor. The resulting hybrid architecture offers a degree of freedom in the management of energy flows and in the sizing of the powertrain. This paper proposes and designs a type-2 fuzzy logic controller based on the intended motor torque and battery state of charge (SOCBat), with the goal of regulating the requested energy consumption while increasing or maintaining driving performance characteristics. This proposed Type-2 fuzzy controller is implemented and evaluated in the onboard hybrid power system simulation model. The results show that the management algorithm can improve its intervention during cycle change and power system efficiency by decreasing variance in battery state of charge. Simulations reveal that the new method is well suited for various driving cycles and severe operational ircumstances.

The crack orientation has a crucial role in the fracture parameters estimation. For this reason, we proposed an inverse approach to detect the orientation of crack within an axisymmetric model based on the particle swarm optimization algorithm. The numerical study of this approach was derived from a finite element model of eddy current testing. The obtained results prove that this algorithm can be a good alternative to the direct method to predict the crack orientation when it is challenging to find crack orientation by eddy current testing.

Although the innovation of sandwich panels in structures is an old technology, it has given great performance by improving the resistance of structures by assembling two metal skins attached to a foam core on either side. In recent decades, sandwiches with composite skins have appeared. This new technology has been reinforced by the development of structural features that, while ensuring a solid link between the two skins, also give the structure resistance to the compressive force that stresses the skins during bending. Our research team is quite intrigued by this particularity, so we are focusing through this investigation on the study of the influence of the modification of the properties of the skin on the static behavior of a stitched sandwich structure. To do this, the study undertaken concerns the numerical analysis of a stitched sandwich structure composed of two equal woven fiberglass/epoxy faces, foam core reinforced with latex wicks under a three-point bending test. Three types of beam samples were studied with material variation of the two skins through a numerical model developed using finite element (FE) analysis software was used to achieve our goal. The results obtained show a significant increase of about three times the stresses and consequently a reduction in the displacements of the global structure.

Recently, physical layer security (PLS) has at- tracted widespread attention to improve security in networks without focusing on encryption tech- niques at the higher layers. This paper proposes a PLS scheme through an orthogonal frequency division multiplexing (OFDM) system based on chaotic maps. An OFDM wave is secured by mixing its modulated symbols and encoding information bits at the same time. Information is encoded by generating a stream of bits by chaotic maps. To build a secure OFDM wave, the modulated symbols are shuffled by a scrambling matrix that is created by chaotic maps. Their initial conditions act as a secret shared key. We send only one key to encrypt the first OFDM signal at the beginning of the transmission. After the first transmission, the received information, after its decryption, serve as the key to the next information. In other word, the information itself is the key to the next information to be received. Meanwhile, we do not have to send the encryption key on every transmission.