Finite pure bending of curved pipes

We present an original treatment for the finite bending of curved pipes with arbitrary cross sections. The curved pipe is successively regarded as a three-dimensional continuum and a shell, and a formulation is proposed for each model. We show that, from a numerical point of view, the finite bending problem is reducible to an axisymmetric analysis augmented with 1 d.f. We also show how to take advantage of this analogy to solve the bending problem using standard axisymmetric FE routines     

Isothermal annealing of antimony-implanted silicon and determination of the lattice disorder profiles

At temperature above about 500°C amorphous layers produced by self ion bombardment of (100) material regrow epitaxially on the underlying crystal, leaving relatively little residual disorder. The epitaxial regrowth from amorphous layers created by antimony implanted into (100) oriented silicon is found to be linear with time. At 500°C the rate on (100) Si is 12 Å/min. For a 60 minutes annealing, a considerable decrease in the amount of defects is observed in the lattice disorder profile.     

A numeric-symbolic approach to the problem of localization of plastic flow

 A method combining numerical and symbolic computations is presented for deciding whether or not a mechanical state given numerically in terms of its fourth-order tensor of moduli satisfies the localization condition, and more generally, any constitutive restriction on the tensor of moduli having a polynomial form. The idea underlying the method consists in posing the problem not as an optimization problem (minimizing the determinant of the acoustic tensor with respect to direction), but as a polynomial inequality. The polynomiality of the problem is then fully taken advantage of by using a powerful algorithm to solve polynomial inequalities: (a simplified version of) Collins' cylindrical algebraic decomposition algorithm. The method was implemented using the computer algebra system Mathematica, which provides accuracy-controlled symbolic and numerical computations and many built-in functions to handle polynomials. These features make it possible to determine the onset of localization more accurately and more reliably than with the usual optimization-based approaches, which are not guaranteed to converge to the global minimum. The potential of the method is illustrated by addressing loss of ellipticity and loss of strong ellipticity in the case of Gurson's porous material.     

Effective thermoelastic properties of composites with temperature-dependent constituents

Effective thermoelastic properties—elasticities, thermal expansions, heat capacities—of composites with temperature-dependent constituents are derived all at the same time using a unified thermodynamic treatment within Kovalenko’s thermoelasticity theory, which assumes the strain to be small but places no restrictions on temperature variations. Known results on elasticities and thermal expansions are rederived in a new way and new results on thermal expansions and heat capacities are obtained. In addition, the temperature-independent framework is revisited and expressions for the effective properties are obtained that are free of the restrictions placed on temperature variations within linear thermoelasticity.     

Formation of Ni2Si silicide in Ni/Si bilayers by ion beam mixing

We have studied ion mixing in Ni-Si(1 1 1) bilayers using noble gas ions. Thin Ni films of 45 nm thickness, deposited on a Si (1 1 1) substrate, were irradiated with 175 keV Kr and 110 keV Ar ions at the same fluence of 4×10¹⁶ ions/cm² at room temperature. The formation of the mixing and the elemental depth profile were investigated by Rutherford backscattering spectrometry. In the Ar irradiated sample, there was no structural change. On the other hand, we have noted the formation of Ni₂Si for the sample irradiated with Kr ions. X-ray diffraction measurements confirmed the formation of the Ni₂Si phase. The surface morphology of the Kr irradiated sample was also studied by scanning electron microscopy.     

Elaboration and Characterization of Amorphous Silicon Carbide Thin Films (a-SiC) by Sputerring Magnetron Technique for Photoelectrochemical CO2 Conversion

Silicon - Semiconductors as photoelectric catalysis is recognized as a promising strategy for simultaneous face energy crisis and environmental pollution. In this study, amorphous silicon carbide...