Thin Indicator Films to Assess the Residual Strength of a GFRP after a Local Contact Action

Two types of thin impact indicator films were developed: made of an epoxy composite with hollow glass microspheres and of a selfadhesive thermoplastic with retroreflective microprisms. They are highly sensitive to local impacts and change the intensity of light reflection in damage zones. Experimental investigations into the residual strength of a GFRP plate covered with indicator films and resting on a rigid basis after its striking by a steel indenter were performed. Numerical models to predict the imprint diameter on the films and the residual strength of a GFRP plate with defect zones after the impact are developed.