Young’s modulus ratio

Fig. 3.5. Dependence of fiber critical aspect ratio, 2L] /d, on the Young s modulus ratio of fiber to...

Fig, 4.35. The relationship between Young s modulus ratio, and radius ratio, b/a, showing the... 

Fig. 7.11. Normalized interface shear stress distributions along the fiber length for composites with and without PVAL coating coating thickness t = 5 pm and Young s modulus ratio of coating to matrix...

Fig. 7.12. Maximum interface shear stresses plotted (a) as a function of Young s modulus ratio of coating to matrix, Ej/Em for coating thickness t = 50 /tm, and (b) as a function of coating thickness t for Young s modulus ratio of coating to matrix, Ei/Em = 0.5. After Kim et al. (1994c)...

Fig. 7.14. Normalized radial residual stresses as a function of coating thickness, I/a, for varying coefficients of thermal expansion (CTE) of the coating, Oc = 10,70,130 x 10 /°C (a) Young s modulus ratio Ej/Em = 0.333 (b) Ei/En, = 1.0. After Kim and Mai (1996a, b).

Young s modulus Ratio of normal stress to corresponding strain for tensile or compressive stresses at less than the proportional limit of the material. 

The microhardness technique is used when the specimen size is small or when a spatial map of the mechanical properties of the material within the micron range is required. Forces of 0.05-2 N are usually applied, yielding indentation depths in the micron range. While microhardness determined from the residual indentation is associated with the permanent plastic deformation induced in the material (see section on Basic Aspects of Indentation), microindentation testing can also provide information about the elastic properties. Indeed, the hardness to Young s modulus ratio HIE has been shown to be directly proportional to the relative depth recovery of the impression in ceramics and metals (2). Moreover, a correlation between the impression dimensions of a rhombus-based pyramidal indentation and the HIE ratio has been found for a wide variety of isotropic poljuneric materials (3). In oriented polymers, the extent of elastic recovery of the imprint along the fiber axis has been correlated to Young s modulus values (4). 

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