Stress-rate effect on time response of mechanoluminescent-sensor luminescent intensity.

The stress dependence of the luminescent intensity (ML intensity) of a mechanoluminescent (ML) sensor, under various load conditions, is investigated. Under load conditions with constant strain, the ML intensity is shown to be proportional to the binder-resin elastic modulus; whereas, under load conditions with a constant stress rate, it is proportional to both the stress and stress-rate. In addition, with stress-rate variations, the ML-intensity rate is proportional to the square of the stress rate. These findings indicate that it is possible to uniquely determine the stress rate by measuring the ML intensity-rate, even if the load conditions are not limited.