ИСТИНА

http://icsi.inegi.up.pt/Programme.pdf The work is aimed at mathematical modeling of coating delamination. Due to difference in geometric parameters of the delaminations it is convenient to use beam, plate or shell theories. The special attention should be given to specifying the appropriate boundary conditions. At first approximation conditions of rigid clamping are used. More accurate results may be obtained using conditions of elastic clamping, where angle of rotation and longitudinal displacement at the clamping point are proportional to the acting moment and longitudinal force (by means of 2x2 matrix of compliance coefficients) [1-4]. However for curvilinear delaminations normal displacements of the points of clamping and transverse forces becomes essential. Therefore the boundary conditions of generalized elastic clamping seems to be more accurate. According to condition of this type the rotation angle and to components of displacement vector at the clamping point are related to the acting moment and two components of the total force by means of 3x3 matrix of compliance coefficients [5]. The scope of tasks to be solved while addressing the problem of coatings delamination includes: (i) obtaining solutions for coefficients of clamping compliance using analytical semi-analytical and numerical methods; (ii) solving problems related to coating delamination in the frame of beam, plate, shell models with the boundary condition of the type of elastic clamping, with parameters determined at the previous step. In particular, reducing the problem of strip attached to a semi-plane or another strip of different material to the matrix Riemann problem and solving it with the Wiener-Hopf method, the asymptotic expression for coefficients of the extended (3x3) matrix of clamping compliance have been obtained for the number of particular configurations. The problem of coating delamination from the cylindrical compliant substrate has been addressed. Two types of prolonged blisters have been considered – along axial and circumferential directions: for each type of blisters the energy release rates have been calculated for their propagation in both axial and circumferential direction. For both cases tendencies for blister elongation has been observed. The general problems of determining the direction of blister propagation and conditions of stability loosing of blister configurations of particular types are also discussed. The obtained results may also be useful for other applications such as interpretations of blister tests.