Texture Young modulus

Strained set of lattice parameters and calculating the stress from the peak shifts, taking into account the angle of the detected sets of planes relative to the surface (see discussion above). If the assumed unstrained lattice parameters are incorrect not all peaks will give the same values. It should be borne in mind that, because of stoichiometry or impurity effects, modified surface films often have unstrained lattice parameters that are different from the same materials in the bulk form. In addition, thin film mechanical properties (Young s modulus and Poisson ratio) can differ from those of bulk materials. Where pronounced texture and stress are present simultaneously analysis can be particularly difficult. 

Polyolefin foams are easier to model than polyurethane (PU) foams, since the polymer mechanical properties does not change with foam density. An increase in water content decreases the density of PU foams, but increases the hard block content of the PU, hence increasing its Young s modulus. However, the microstructure of semi-crystalline PE and PP in foams is not spherulitic, as in bulk mouldings. Rodriguez-Perez and co-workers (20) showed that the cell faces in PE foams contain oriented crystals. Consequently, their properties are anisotropic. Mechanical data for PE or PP injection mouldings should not be used for modelling foam properties. Ideally the mechanical properties of the PE/PP in the cell faces should be measured. However, as such data is not available, it is possible to use data for blown PE film, since this is also biaxially stretched, and the texture of the crystalline orientation is known to be similar to that in foam faces. 

The functionally graded materials (FGMs) are characterised by a non-linear 3D-distribution of phases and corresponding properties [1,2]. They are distinguished from isotropic materials by gradients of composition, phase distribution, porosity, texture, and related properties (hardness, density, resistance, thermal conductivity. Young s modulus, etc.) [3-5]. The FGM is characterised not only by the presence and appearance of compositional or other gradients but also by the sophisticated behaviour of FGM component in comparison with conventional (macroscopically uniform) materials. 

Table 1. Texture and Young s modulus E of drawn and restored (4 months at 20°C) 38 xm diameter Cu...

Unfortunately, the directional dependence is similar to that of Young s modulus. The stress-reducing effect of Young s modulus in textured wires is therefore partially compensated by the corresponding reduction of the yield stress. But the reduction of Young s modulus between its extremal values in the (111) and (100) directions is about twice the reduction of the yield stress between the same directions. 

In Fig. 4.61, the Young s modulus and hardness are shown for textured alumina obtained by spark plasma sintering [henceforth SPS] of undoped commercial... 

Returning to the static moduH, the subject of this section. Fig. 12.1 serves as a reminder of the definitions of the engineering quantities bulk modulus (K), shear modulus (G), Young s modulus E), and Poisson s ratio (v), which in an isotopi-cally elastic soHd (fine, randomly textured grains) are simply related to each other according to ... 

Pi om a mesoscopic point of view, when a semicrystalline polymer is submitted to a large deformation, the spherulitic structure is gradually broken down, while increasing moleculai orientation. In a tensile deformation, the spherulitic could be reformed ultimately in a new oriented microstructure the oriented fibrillar texture [190]. Such cold processed polymer fibers may have a Young s modulus, which could nearly reach 150 GPa for polyaramid fibers (Kevlar ). The strong link between microstructme and mechanical properties can be easily predicted. 

Young s modulus for a polycrystalline material without texture, and expressed in K and G, is exactly given by... 

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