Mechanoluminescent Materials: A New Way to Analyze Stress by Light

Abstract

Abstract:The monitoring of stress changes in structural components under various kinds of dynamical loading is crucial for the assessment of their integrity and lifetime. In addition to many methodologies available, such as strain gauges, optical fiber sensors, X-Ray diffraction and digital image correlation, we introduce a novel non-contact method to visualize stress distributions based on mechanoluminescence (ML). ML is a phenomenon occurring in some materials that emit light upon an applied stress level. In this paper, we develop the ML material (Ca0.4Sr0.6)Al2Si2O8:1%Eu 2+ ,1%Ho 3+ , a glow-in-the-dark material, to visualize stress distribution in a disc, as well as the stress field of an ultrasonic transducer. The properties of defects in the ML phosphors, which are responsible for ML in this material, are vital for stress visualization.

Near infrared mechanoluminescence from Sr3Sn2O7: Nd3+for in situ biomechanical sensor and dynamic pressure mapping

“…Interestingly, as Figure B denotes, the six ML intensities can be fitted into a linear equation of y = 0.30 x –65.34 where y represents the ML intensity and x is the force. A high linearity between force and ML intensity is a prerequisite for stress sensor, since this emission performance will allow visualization of stress distribution with high spatial resolution. The higher is the linearity, the more precise is the stress distribution visualization.…”

“…In order to figure out the related NIR ML mechanism, we carried out various forms of ML experiments . We first explored the effect of different kinds of external mechanical stimuli on ML in Figure A such as compressive load and friction (ML produced under friction is usually termed as tribo‐ML (TML)).…”

“…In order to figure out the related NIR ML mechanism, we carried out various forms of ML experiments. 1,26 We first explored the effect of different kinds of external mechanical stimuli on ML in Figure 5A such as compressive load and friction (ML produced under friction is usually termed as tribo-ML (TML)). The ML, TML, and PL spectra peaks are all located in 900 nm, which indicates that the involved electronic transitions in ML and TML are similar to PL after excitation.…”

“…Mechanoluminescence (ML) is defined as a type of mechano‐optical luminescence, in which materials respond to various mechanical stimuli such as friction, tension, fracture, and compression . To date, ML can be classified into fracto‐ML and deformation‐ML.…”

Persistent Luminescence in Strontium Aluminate: A Roadmap to a Brighter Future

“…[215,219,220,222,223] This decaying trend of ML under constant load has been detected in ML phosphors other than SrAl 2 O 4 :Eu 2+ as well, such as (Ba,Ca) TiO 3 :Pr 3+ , [224] BaSi 2 O 2 N 2 :Eu 2+ , [225] (Ca,Sr)Al 2 Si 2 O 8 :Eu 2+ ,Pr 3+ , etc. [226] Furthermore, for a repetitive triangular stress profile, the ML intensity at the maximum stress decreases with increasing cycling number N but can restore to the initial value (N = 1) after sufficient optical charging. [227] The implication from these findings is at least twofold.…”