Stress memory for the visualization detection of complicated mechanical structures via trap structure manipulation

Abstract

The detection of the stress distribution in a mechanical structure signifies a timely prediction of the deformation and damage of the corresponding object, which is crucial for engineering security management and construction safety. However, current strategies with 3-dimensional force detection of the targets are challenged by complicated mechanical structures. Herein, dynamic recording via stress memory with visualization detection for a gear with a highly curved surface is achieved using the explored mechanoluminescent film combined with Sr₄Al₁₄O₂₅:Eu²⁺, Tm³⁺ microparticles. The regulated depth of the traps from 0.74 to 1.0 eV with the addition of foreign ions in Sr₄Al₁₄O₂₅:Eu²⁺ allows for the stabilization of the captured carriers. Moreover, the external force accelerates the release of the captured carriers, with no stress-induced generation of long persistent luminescence, and the residual carriers could be readout by the introduction of a near-infrared light. This realizes the visualization of the stress distribution of complicated mechanical structures directly. Hence, the stress memory properties of mechanoluminescent films provide a novel approach for the stress detection of non-planar mechanical components in different scenarios.