Bulk compressive strain

Note Also referred to as volume compression, isotropic compression and bulk compressive strain. 

Bulk Compressibility and Bulk Modulus is one of the important constants of aa elastic solid Bulk modulus is defined as the tatio of stress to atrsin when the stress is a pressure applied equally on all surfaces of the sample and the strain is the resulting change in volume per suit volume. The reciprocal of bulk modulus Is called bulk compressibility. One apparatus for the direct exnd measurement of the dynamic bulk modulus of a solid was developed at the NOL, White Oak, Md(Ref 1). Some data obtained, on several HE a, using this apparatus are given in Refa 2, Refs l)NAVORD Kept No 1534(1950) 2)NAVORD Rept No 4380(1956) 3)PATR 1740,Rev 1(1958)... 

Koschnick et al [59] report an EFG of 6.50 x 1020 V/m2 for their thin film sample (similar to the results of NMR and the Overhauser shift measurements) while Glaser et al [60] report EFGs of 5.91 x 1020 V/m2 and 5.32 x 1020 V/m2 for two different thin film samples. The disparity in these values is more than can be accounted for by experimental errors. Glaser and co-workers [61] have compared their results with the in-plane compressive strain ( 2 - 3 x 10 3) measured by X-ray diffraction and assumed the EFG obtained from the Overhauser shift measurements represents an unstrained GaN crystal. The reduction of the EFG with compressive strain indicates that the atoms in the fihns are in a somewhat more tetrahedral environment than those in the bulk, suggesting that the c-direction Ga-N braid is somewhat shorter than the three others in both the films and the bulk. This is consistent with the ratio of lattice constants, c/a, being less that the ideal value of (8/3)1/2... 

Next, compressive and tensile biaxial strain effects are discussed, because biaxial strains are usually adopted to reduce the threshold carrier density in conventional ZB QWs. FIGURE 5 shows the maximum optical gain of biaxially strained ZB GaN/Alo.2Gao. N QWs with well width Lz = 60 A. The compressive biaxial strain strongly depresses the TM-mode optical gain and enhances the TE-mode optical gain. On the other hand, the effect of tensile biaxial strain is the reverse of that of compressive strain. These results can easily be understood from the feature of bulk ZB GaN, where compressive... 

A way to stretch or compress metal surface atoms in a controlled way is to deposit them on top of a substrate with similar crystal symmetry, yet with different atomic diameter and lattice constant. Such a single monolayer of a metal supported on another is called an overlayer. Metal overlayers strive to approach the lattice constant of their substrate without fully attaining it hence, they are strained compared to their own bulk state [24, 25]. The choice of suitable metal substrates enables tuning of the strain in the overlayer and of the chemisorption energy of adsorbates. A Pt monolayer on a Cu substrate, for instance, was shown to bind adsorbates much weaker than bulk platinum due to compressive strain induced by the lattice mismatch between Pt and Cu, with Cu being smaller [26]. 

The fluid compression energy up to about 150 MN/m (22,000 psig) can be estimated from Uf= V2 tP Vl, where Pr is the liquid bulk compressibility, P is the liquid pressure, and Vi is the liquid volume. At higher pressure, this simple equation becomes too conservative and more complex methods of calculating the fluid compression energy are required. The elastic strain energy for cylindrical vessels, ignoring end closures, can be estimated from ... 

Sn to the surface increases. This is a consequence of the repulsion between Sn atoms in the surface due to Sn-induced compressive strain in the surface layer. The differential segregation energy in Fig. 13.5 is calculated so that the zero energy corresponds to a surface Sn concentration that gives an equal probability of Sn in the surface layer at the given concentration and Sn in dilute limit in the bulk. 

When S 1, bulging can only occur near the sides of the block. Near the centre, the rubber compresses in volume with zero lateral strains, in uniform stress conditions. Therefore, the volume strain dV/V is approximately equal to the vertical compressive strain, except at the edges of the plates. From the definition of the bulk modulus K in Eq. (3.30), we find that, in the limit as 5 tends to infinity... 

The bulk modulus of rubber, which depends on the strength of the van der Waals forces between the molecules, is 2 GPa. Therefore, the compressive modulus of a rubber layer increases by a factor of a thousand as the shape factor increases from 0.2 (Fig. 4.3). The responses are not shown for S < 0.2 such tall, thin rubber blocks would buckle elastically (Appendix C, Section C. 1.4), rather than deforming uniformly. When laminated rubber springs are designed, Eqs (4.5) and (4.7) allow the independent manipulation of the shear and compressive stiffness. The physical size of the bearing will be determined by factors such as the load bearing ability of the abutting concrete material, or a limit on the allowable rubber shear strain to 7 < 0.5 and the compressive strain e < -0.1. 

Under small deformations rubbers are linearly elastic solids. Because of high modulus of bulk compression (about 2000 MN/m ) compared with the shear modulus G (about 0.2-5 MN/m ), they may be regarded as relatively incompressible. The elastic behavior under small strains can thus be described by a single elastic constant G. Poisson s ratio is effectively 1/2, and Young s modulus E is given by 3G, to good approximation. 

Fig. 1.4 PIml deposition by galvanic displacement of a Cu UPD adlayer on the substrates of bulk Pd electrode (a) and Pd nanoparticle (b). Models of pseudomorphic monolayers of Pt on three different substrates (c) inducing compressive strain (Ru(0001) and Pd(ll 1)) and expansive strain...

Polyurea-crosslinked TMOS APTES aerogels by reaction with Desmodur N3200 di-isocyanate with bulk density /C)b = 0.48 gcm are translucent (as opposed to opaque. Figure 13.5) and have a thermal conductivity of about 0.041 W m K which is comparable to that of glass wool [54]. Under compression, the samples do not swell or buckle showing a brief linearly elastic range (at <4% strain) followed by ductile behavior with plastic deformation (until 40% compressive strain) and inelastic hardening... 

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