In this lecture prof C. Kassapoglou talks about the how problem of skin-stiffener separation arises and how to determine the stresses at the interface.
After clearly defining the problem he starts by explaining the Euler-Lagrange equation, which is a differential equation can be used to minimize or maximize a function using calculus of variations. He then writes out the stress equilibrium equations and applies them to a generalized case to find expressions that can be used in the Euler-Lagrange equation to find a minimized solution.
Finally the Euler-Lagrange equation is applied on the stress relations, and known boundary conditions are used to find an expression for the skin-stiffener interface stresses.
AE4509 Energy methods for buckling of skin stiffened plates
Advanced Design and Optimization of Composite Structures I by TU Delft OpenCourseWare is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
Based on a work at https://ocw.tudelft.nl/courses/advanced-design-optimization-composite-structures/.