Axial compression-induced wrinkles on a core-shell soft cylinder: Theoretical analysis, simulations and experiments

摘要

Surface wrinkling of a cylindrical shell supported by a soft core subjected to axial compression is investigated via combined experimental, computational and theoretical efforts. Our experiments show that the post-bifurcation deformation mode of the system is axisymmetric when the modulus ratio of the surface layer to the core is small while a non-axisymmetric wrinkling pattern appears when the modulus ratio is large. Our nonlinear finite element simulations have confirmed this experimental finding. A theoretical analysis based on Koiter's elastic stability theory is carried out to reveal the mechanisms underpinning the phenomenon of morphological evolution. The critical buckling analysis shows that the first bifurcation mode is axisymmetric for arbitrary modulus ratios of the shell to the core. Post-bifurcation analysis reveals that the system will evolve into a diamond-like mode when the modulus ratio is large enough but keep the axisymmetric mode if the modulus ratio is smaller than a critical value. The results can guide the creation of controlled surface wrinkles on a cylindrical surface under compression. Besides, the analysis approach presented here may be adopted to understand the wrinkling patterns observed in some natural systems generated by, for instance, differential growth.