Lamd constants

If the film is acoustically thin 1), then displacements are constant across the film thickness, and only gradients in the plane of the film arise. The SAW-induced film deformation can be decomposed into three translations (in the x-, y-, and z-directions) and three strain modes, as shown in Figure 3.29 (page 94). An important parameter in determining the contribution of each strain mode in perturbing SAW propagation is the modulus — the ratio of stress to strain associated with each strain mode in Figure 3.29. These moduli are listed in Table 3.3 in terms of the intrinsic elastic properties of the film, represented in terms of the Lamd constants (A, p) and the bulk and shear moduli (AT, G). These sets of moduli are interrelated [51]. 

Some texts use a pair of related elastic constants X and p.. These are known as the Lamd constants. We already... 

Values of the shear modulus, Lamd s constant and Poisson s ratio for representative solids are given in Table E.2. 

---