Dynamic Visualization of Stress/Strain Distribution and Fatigue Crack Propagation by an Organic Mechanoresponsive AIE Luminogen

Abstract

Stress exists ubiquitously and is critically important for the manufacturing industry. Due to the ultrasensitive mechanoresponse of the emission of 1,1,2,2,-tetrakis(4-nitrophenyl)ethane (TPE-4N), a luminogen with aggregation-induced emission characteristics, the visualization of stress/strain distributions on metal specimens with a pure organic fluorescent material is achieved. Such a fluorescence mapping method enjoys the merits of simple setup, real-time, full-field, on-site, and direct visualization. Surface analysis shows that TPE-4N can form a nonfluorescent, crystalline uniform film on the metal surface, which cracks into fluorescent amorphous fragments upon mechanical force. Therefore, the invisible information of the stress/strain distribution of the metal specimens are transformed to visible fluorescent signals, which generally matches well but provides more details than software simulation. Remarkably, fatigue crack propagation in stainless steel and aluminum alloy can be observed and predicted clearly, further demonstrating the ultrasensitivity and practicability of TPE-4N.

Aggregation‐Induced Emission Properties of Copper Iodide Clusters

“…In recenty ears, the great development of AIE compounds is relatedtomultiple potential applications, including luminescent probes for biomedical imaging and sensing applications, which are under intensive development. [9][10][11][12][13][14][15][16][17][18] Because of their twisted conformations, AIE-active organic molecules usually aggregate into al oosely( defective) packed solid state that facilitates their transformation between differ-ent molecular arrangements. This characteristicc onfers an enhanced sensitivity to externals timuli and, in particular, to mechanical forces onto thesec ompounds.…”

Aggregation‐Induced Emission for Visualization in Materials Science

“…(E) Working mechanism for stress/strain visualization. [76] have been realized and well investigated. The unique fluorescent behaviors provide severala dvantages for visualization in materials science.…”

“…Zhang, Tang, and co-workers have found that the tetrakis(4-nitrophenyl)ethane( TPE-4N) exhibited as ensitivef luorescent response towards mechanical stimulus. [76] The TPE-4N molecules showedn oe mission in their crystalline form, and strong fluorescent emission can be observedf or their amorphous fragments upon mechanical force. Notably,t he fluorescence intensity ratio in amorphous and crystalline states is up to 23, suggesting the high contrast and sensitivity of the molecules in different states.…”

“…To visualize the distribution and concentration of stress in a nondestructive and on‐site approach, AIE molecules were employed. Zhang, Tang, and co‐workers have found that the tetrakis(4‐nitrophenyl)ethane (TPE‐4N) exhibited a sensitive fluorescent response towards mechanical stimulus . The TPE‐4N molecules showed no emission in their crystalline form, and strong fluorescent emission can be observed for their amorphous fragments upon mechanical force.…”

“… (A) Fluorescence image and (B–D) SEM images of fractured steel tensile specimen and the selected areas (1–3) for surface analysis. (E) Working mechanism for stress/strain visualization …”