In transversely separable shell structures, a thin metal shell is surrounded by a rigid medium. The proposed approach to solving delamination problems in such constructions is based on three points: the introduction of technological deviations (corresponding to permissible defects in actual structures) to the computation scheme of the structure; the determination of the volumetric general stress-strain state of the structure; real-time structure deformation accounting. The approach is implemented in the LS-DYNA software package in a dynamic formulation using finite elements TSHELL and SOLID, taking into account the geometric and physical nonlinearity of the structure and the shell — medium contact surface with unilateral constraint along normal line, without tangent interactions. According to the proposed approach, the result of calculations is the assessment of the loads on the initial two-layer structure, under which a metal shell with low bending stiffness can lose stability in the local area in the form of internal wrinkles.
An example of the calculation of a cylindrical metal-composite high-pressure vessel under loading by a cooled external composite shell is given. The time intervals of the onset of delamination and growth of wrinkles on the surface of the inner metal shell (liner) are established. The solutions are presented in the form of images of the deformed surface of the liner and graphs of time-dependent changes in stresses, strains and displacements; their correspondences to each other are shown. The proposed approach allows one by visual demonstration and accurately to assess the possibility of delamination in contact-constrained shell structures already at the design stage.