Monitoring stress concentration in polymers with circular notch exploiting graphene-based sensors

Failure of polymers frequently initiates at discontinuities in the material, such as holes and notches, as they constitute points of increased stress concentration. Herein, we propose the use of monolayer graphene produced via Chemical Vapour Deposition to monitor the stress distribution close to a defect in poly(methyl methacrylate). Combining in-situ Raman spectroscopic mapping with tensile tests, the stress/strain distribution around the defect can be probed via monitoring the wavenumber shift of the spectroscopic features of graphene. The measured stress concentration factor of 2.41 is remarkably close to the value derived from Finite Element Analysis, and agrees with other studies in the literature, thus demonstrating that the proposed technique is reliable, and that graphene can accurately sense stress concentration close to a defect, with a sub-micron spatial resolution and a strain resolution of ≈60 με.