Mechanoluminescence visual inspection of microcrack generation through fatigue process in flexible electronic films

Abstract

We propose a novel method for filling a gap in originally invisible mechanical behavior in modeling, evaluation and products by using mechanoluminescent (ML) visual sensing. To demonstrate the effect of the method, mechanical information was evaluated in folding tests of flexible electronic films. As a result, the appearance of strain concentration was successfully visualized on the basis of mechanoluminescence, and complex dynamic mechanical information was instinctively understood from the time course of the ML patterns. In addition, the ML pattern clearly depends on the sticking situation of the flexible film on a folding plate with gripping tape even in the same test conditions such as the same folding radius, material and thickness which are considerable major factors in mechanical behavior at folding. Moreover, microcrack generation was detected during the folding cycle as blinking of ML points, and it occurred even from a 10-cycle fatigue of the flexible film in endurance folding tests.