RT Journal Article A1 Yiyu CAI,Sibo LIU,Lei ZHAO,Chao WANG,Hongyu LV,Bitao LIU,Jianbei QIU,Xuhui XU,Xue YU; AD School of Mechanical Engineering, 中国 ; 云南省先进材料重点实验室, 中国 ; 骨科, 1440581275736453121, 中国 ; 物理与光电子技术学院, 中国 ; 云南省先进材料重点实验室, 中国 ; 云南省先进材料重点实验室, 中国 ; 新材料技术研究所, 中国 ; 云南省先进材料重点实验室, 中国 ; School of Mechanical Engineering, 中国 ; 云南省先进材料重点实验室, 中国 ; School of Mechanical Engineering, 中国 ; 云南省先进材料重点实验室, 中国 T1 Delayed stress memory by CaAl2O4:Eu2+ mechanoluminescent phosphor with defect engineering regulation YR 2022 IS 8 vo 11 OP 1319-OP 1329 K1 defect engineering;delayed stress memory;mechanoluminescent film;stress information;closed mechanical structure AB Real-time stress sensing based on mechanoluminescence materials has been widely studied for structural health monitoring of bridges, buildings, high-pressure vessels, and other infrastructure surfaces. However, this approach is difficult to detect the stress information of closed mechanical structures. Here, we propose a delayed stress memory strategy to record the stress information of closed mechanical structure by the flexible film composed with CaAl2O4:Eu2+,Sm3+ phosphor. After the force is applied, the optical information on the film can be read out by the near-infrared laser after a period of time without real-time monitoring, and the stress distribution information of bearings and gears in the engine can be obtained. Furthermore, the regulation of trap depth from 0.662 to 1.042 eV allows the captured carriers to remain in the traps for a long time without being released as long persistent luminescence, which is beneficial to the delayed stress memory. Therefore, this work promotes the application prospect of mechanoluminescence materials in stress sensing, and provides a new idea to record the stress information of closed mechanical structures. SN 2226-4108 LA EN