Self-sensing solid materials via delamination buckling

Strain in solid materials under external loads cannot be visualized until they reach a high value or failure occurs; and the common measuring method of using strain sensors is effective but limited to wiring or power supply. In this study, we introduce a new concept of self-sensing solid materials by designing thin surface circular delamination regions on a material body to sense and predict the elastic global strain through controlled elastic local buckling. Delamination buckling is an undesirable failure occurrence in laminated composites under compression. However, it can translate imperceptible small global strains on the main material body to a visible large deformation in the surface of the delaminated region due to buckling. We analytically studied the buckling and post-buckling response of a clamped circular thin plate with unilateral constraint using an energy method to obtain the critical buckling loads, the buckling configurations, and the center out-of-plane displacement under uniaxial and biaxial loading conditions. The results show that for a given buckling configuration in the local region, the global strain condition of the main material body can be predicted. The study thus explores and proves a feasible way to design selfsensing materials through controlled delamination buckling.