Quantifying the Coupling between Mechanoluminescence Intensity and Elastic Strain Energy Power Density

Abstract Mechanoluminescence (ML) offers unique advantages for self‐powered sensing and structural health monitoring. While ML intensity is known to correlate with various mechanical parameters, a unified physical descriptor remains elusive. Here, a quantitative relationship is established between ML intensity ( I _ML ) and elastic strain energy power density ( P ) based on a trap‐controlled luminescence model that incorporates piezoelectric field‐induced trap‐depth reduction and the contribution of stress‐induced afterglow (SAG). Using SrAl ₂ O ₄ :Eu ²⁺ as a model material, we validate the proposed model through Zr ⁴⁺ doping modulation, finite element analysis of stress distribution, and compression experiments across varied strain rates. The results reveal a linear I _ML ‐P relationship under rapid loading, while slower rates induce significant SAG overlap, leading to nonlinear deviation. This deviation increases with extended stress duration. The findings identify elastic strain energy power density as a governing parameter for ML emission, offering a unified metric to guide material evaluation and device design. This work bridges mechanical input with optical output and provides a robust theoretical‐experimental framework for the rational development of ML‐based visualization technologies.