In this study, a finite element (FE) model is proposed to study the thermal transverse vibrations of cracked nanobeams resting on a double-parameter nonlocal elastic foundation. Hamilton's principal is employed to derive the governing equations for the free vibrations of the nanobeam. The cracked section of the beam is modelled by dividing the cracked element into two classical beam sections connected via a rotational spring positioned at the crack. The Galerkin method of weighted residuals is used to solve the equations of motion and calculate the natural frequencies. The effect of the crack length, crack position, the temperature gradient, the boundary conditions and the foundation stiffness, on the vibration response of the cracked nanobeams supported by elastic foundations is considered by including thermal effects. The FE results are compared to the available benchmark studies in the literature.
In the present work, the deformation textures during flat profile extrusion from round billets of an AA6063 and an AA6082 aluminium alloy have been numerically modeled by coupling FEM flow simulations and crystal plasticity simulations and compared to experimentally measured textures obtained by electron back-scatter diffraction (EBSD). The AA6063 alloy was extruded at a relatively low temperature (350°C), while the AA6082 alloy, containing dispersoids that prevent recrystallization, was extruded at a higher temperature (500°C). Both alloys were water quenched at the exit of the die, to maintain the deformation texture after extrusion. In the center of the profiles, both alloys exhibit a conventional β-fiber texture and the Cube component, which was significantly stronger at the highest extrusion temperature. The classical full-constraint (FC)-Taylor and the Alamel grain cluster model were employed for the texture predictions. Both models were implemented using the regularized single crystal yield surface. This approach enables activation of any number and type of slip systems, as well as accounting for strain rate sensitivity, which are important at 350°C and 500°C. The strength of the nonoctahedral slips and the strain-rate sensitivity were varied by a global optimization algorithm. At 350°C, a good fit could be obtained both with the FC Taylor and the Alamel model, although the Alamel model clearly performs the best. However, even with rate sensitivity and nonoctahedral slip systems invoked, none of the models are capable of predicting the strong Cube component observed experimentally at 500°C.
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