Stress/strain and curvature analysis of laser-scribed polyethylene terephthalate films with multiple grooves using finite element method

Laser scribing can be used to enhance the flexibility of polymer films for flexible device applications. To optimize the bending curvature by controlling the scribing parameters—the depth, number, and interval of the scribed grooves, finite element analysis was conducted on the bending tests of scribed polyethylene terephthalate films. Moreover, the influences of the parameters on the stress/strain near the grooves were investigated. The maximum stress/strain and curvature generally increased with an increase in depth, whereas these values decreased with an increase in number and intervals. However, to maintain the mechanical stability of the films, the parameters were limited. The optimization results revealed that the maximum value of the curvature was 2.6 mm⁻¹ at depth = 40 and intervals = 25 μm, for number = 7. An empirical equation relating the curvature to depth and intervals was also provided. The results of the analysis are useful for the design of laser-scribed grooves on various polymer films, for the enhancement of their bending curvature, while minimizing the mechanical instability.