To solve Eq. 13.2, an initial distribution for residual stress must be considered. Two conventional methods of approximation of residual stresses in slitting method include the ‘Series Expansion Method’ and the ‘Pulse Method’ (Prime, 1999). In the application of the series expansion method to the isotropic materials, the residual stress profile along the specimen thickness is often approximated by a continuous polynomial (typically Legendre polynomials) with unknown coefficients. Then the unknown coefficients are determined from compliance coefficients and the measured strain data. In layered materials like laminated composites, because of discontinuity of material properties across layers boundaries, the stress profile is not continuous. Therefore, the series expansion method cannot be used for laminated composites.