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Elastic Properties of Solids

DOI 10.1615/hedhme.a.000531

5.5 PHYSICAL PROPERTY DATA TABLES
5.5.8 Elastic properties of solids

Comparison of the values for an elastic property of a particular metal or alloy quoted in the various data books and published in original papers indicates a remarkably wide spread. For any given material, values differing by 20% are quite common. Therefore any calculation using elastic properties as input data should explicitly declare the values that have been taken.

The sources of error in measurement of clastic properties arise partly from difficulties in measurement of clastic strain. The quantity to be measured is at most a few parts per thousand changes in length and to be measured with two to three figure accuracy. Other sources of error are more fundamental. For example, in the preparation of specimens for measurement of elastic properties, a certain degree of preferred orientation of the individual grains is introduced, thus affecting the properties in the ways described in Section 522. It should also be realized that data for isotropic material may not best represent the properties of components that might have developed preferred orientation of the grains during fabrication. Finally, both at room temperature and to a greater extent at elevated temperatures and at high stress levels stress-strain response of a specimen is time dependent and structure sensitive.

Where high accuracy is required as for example, in attempting to understand the performance of a particular fabricated heat exchanger, the best procedure would be to measure the elastic properties on samples of the actual materials at the appropriate temperature and strain rate.

Table 1 and Table 2 show single crystal clastic coefficients for hexagonal and cubic metals, respectively (Tang et al., 1969 and Smithells, 1967). They are included here to indicate the extent to which elastic anisotropy can be expected in wrought polycrystalline materials with preferred orientation of the grains.

Table 1 Single crystal clastic constants of some hexagonal metals in gigapascals a

a From Tang et al. (1969). (Giga = 109.)
bC = C11 + C12 + 2C33 – 4C13
MetalShear constants
C11C33 C12 C13 C44 C66C b/6
Beryllium299 342 28 11 166 136161
Zinc161 66 34 50 40 6321
Magnesium57 62 23 19 17 1721
Zirconium144 165 73 65 33 3647
Titanium163 180 93 62 47 3562
Cadmium115 51 40 40 20 3816

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