Mechanoluminescent Probing of Elastic Moduli in CaZnOS:Mn 2+ , Bi 3+ Composites: Effects of Matrix Modulus and Filler Loading

Abstract Mechanoluminescent (ML) materials directly convert mechanical stimuli, such as friction and compression, into light without an external power source. In this study, CaZnOS:Mn 2+ , Bi 3+ phosphors are embedded into two epoxy matrices (Loctite E‐30CL and E‐51) to create ML composite cylinders, enabling a systematic comparison of matrix effects under end‐face rotational sliding and Hertzian line‐contact compression. Initially, the effective Young's modulus and Poisson's ratio of the composites are predicted using a simplified scalar form of the Mori–Tanaka micromechanics model and validated these predictions with representative‐volume‐element finite‐element simulations. The derived mechanical parameters are then incorporated into contact‐mechanics formulations and ANSYS simulations to determine the stress fields under Hertzian loading. Based on Hertz theory, a quantitative stress–luminescence model is developed that explains why the higher‐modulus matrix (E‐51) induces stronger stress concentrations and, consequently, higher ML intensity. Experimental results demonstrate that E‐51‐based composites produce greater light output under both frictional and compressive loading and that increasing the ML particle volume fraction further improves composite stiffness and ML sensitivity. Overall, an integrated theoretical–numerical–experimental framework for force–light coupling is presented, enabling performance prediction and device optimisation of ML composites.