In this paper we study linear elasticity equations in an infinite elastic strip with a semi-infinite crack. We find the derivative of the energy functional as the crack shifts with an angle. Then we obtain the formula given by surface force and the angle.
"Shape Derivative of Energy Functional in an Infinite Elastic Strip with a Semi-Infinite Crack." Tokyo J. Math. 29 (2) 385 - 397, December 2006. https://doi.org/10.3836/tjm/1170348173