Unequal load sharing across interfaces limits adhesive strength. This is equivalent to stress concentrations leading to crack propagation. Functionally graded interfacial properties can counteract unequal load sharing and maximize the adhesive strength. This was demonstrated empirically via numerical simulation  and now finally in closed form analytic solution . As shown in the figure (from ), the equal load sharing (ELS) reduces load concentrations and increments adhesive strength. This occurs even in the presence of interfacial misalignment [1-2].
 Bacca, M., Booth, J. A., Turner, K. L., and McMeeking, R. M., 2016, “Load Sharing in Bioinspired Fibrillar Adhesives With Backing Layer Interactions and Interfacial Misalignment,” J. Mech. Phys. Solids, 96, pp. 428–444.
 Khungura, H., Bacca, M., 2020, “Optimal Load Sharing in Bioinspired Fibrillar Adhesives: Asymptotic Solution,” J. Appl. Mech. 88, pp. 031004-1.