TABLE 1 Coefficients Ayu in Eq (2)[11] 2μ=3=4 0.498 1.3187 3.067 50806243447-32.7208181214 63-12641519.763 n+1 2 Fig. I Fig. 1. Scheme of the two-component multilayer specimen Fig. 2. Scheme of analyze d crack location in layered specimen. where x is the distance along the crack length measured from the surface of an edge crack, a is the crack length a=a/w, and w is the specimen thickness(Fig. 2). For edge-cracked specimens, Fett and Munz[ll] have developed the following weight function -a)32+∑ of the coefficients Ayu and the exponents v and H in(2)are listed in Table 1 In the case where deformation is a function of coordinate x only, it follows from the strain compatibility [12] that overall deformation E(r) must be linear for elastic material E(x)=Eo +k (3) Here Eo is the deformation at x=0, and k is the specimen curvature. An equal biaxial stressed state is known to be the most appropriate approximation to describe the stressed state in real layered specimens [13]. This is the case of infinite dimensions along directions y and z, but with finite value of the specimen thickness. In the equal biaxial stressed state, we have: E(x)=Ez =E w, o(r)=02=Ow, where Ez, E w, Oz, and o w are strain and stress components along z-and y-axis respectively. Edge effects(occurrence of three-dimensional stresses near the edges of layered composite over a distance from the edge which is approximately equal to the layer thickness [14)can be neglected due to their high-localized character. Then o(x)=E'(x)e(x)-E(x)],where x is the distance along the crack length measured from the surface of an edge crack, a is the crack length, α = a w, and w is the specimen thickness (Fig. 2). For edge-cracked specimens, Fett and Munz [11] have developed the following weight function: h x a a x a , A ( ) ( ) α ( ) π α α νµ ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ = − ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ − − + 2 1 1 1 1 1 2 1 2 3 2 3 2 − ⎛ ⎝ ⎜ ⎞ ⎠ ⎟ ⎡ ⎣ ⎢ ⎢ ⎤ ⎦ ⎥ ⎥ + ∑ x a ν µ α 1 . (2) The values of the coefficients Aνµ and the exponents ν and µ in (2) are listed in Table 1. In the case where deformation is a function of coordinate x only, it follows from the strain compatibility [12] that overall deformation ε( ) x must be linear for elastic material: ε ε () . x kx = + 0 (3) Here ε 0 is the deformation at x = 0, and k is the specimen curvature. An equal biaxial stressed state is known to be the most appropriate approximation to describe the stressed state in real layered specimens [13]. This is the case of infinite dimensions along directions y and z, but with finite value of the specimen thickness. In the equal biaxial stressed state, we have: ε εε ( ) x = = zz yy , σ σσ () , x = = zz yy where ε zz, ε yy , σ zz, and σ yy are strain and stress components along z- and y-axis respectively. Edge effects (occurrence of three-dimensional stresses near the edges of layered composite over a distance from the edge which is approximately equal to the layer thickness [14]) can be neglected due to their high-localized character. Then σ εε ( ) ( )[ ( ) ~ x Ex x x = ′ − ( )], (4) 293 TABLE 1. Coefficients Aνµ in Eq. (2) [11] ν Aνµ µ = 0 µ = 1 µ = 2 µ = 3 µ = 4 0 0.498 2.4463 0.07 1.3187 − 3.067 1 0.54165 − 5.0806 24.3447 − 32.7208 18.1214 2 − 0.19277 2.55863 − 12.6415 19.763 − 10.986 Fig. 1 Fig. 2 Fig. 1. Scheme of the two-component multilayer specimen. Fig. 2. Scheme of analyzed crack location in layered specimen