Improving the Sensitivity of the Mechanoluminescence Composite through Functionalization for Structural Health...

Area of Science:

• Materials Science
• Nondestructive Testing
• Solid Mechanics

Background:

• Mechanoluminescence (ML)-based stress sensing is a developing nondestructive inspection (NDI) technique.
• A key challenge is the limited luminescent intensity and sensitivity of ML-epoxy composites to stress fields.
• Improving the sensitivity of ML composites is crucial for practical NDI applications.

Purpose of the Study:

• To enhance the sensitivity of ML-epoxy composites for stress sensing.
• To investigate the effect of surface modification of ML particles on luminescent sensitivity and interfacial bonding.
• To demonstrate the capability of the modified ML/epoxy paint for visualizing stress fields and detecting cracks.

Main Methods:

• Surface functionalization of SrAl2O4:Eu2+, Dy3+ ML particles with (3-aminopropyl)triethoxysilane.
• Tensile testing of modified ML-epoxy composite specimens.
• Characterization of modified surfaces and interfacial bonding.
• Application of ML/epoxy paint on notched specimens and comparison with finite-element analysis (FEA).

Main Results:

• Surface modification of ML particles significantly increased luminescent sensitivity.
• New chemical bonds formed, enhancing stress transfer through improved interfacial bonding.
• The ML film successfully visualized stress concentration patterns around a notch, correlating with FEA results.
• The light intensity distribution directly reflected the presence and pattern of the crack.

Conclusions:

• The proposed surface modification method effectively enhances the sensitivity of ML composites for stress sensing.
• The enhanced ML film can visualize stress fields and nondestructively detect cracks, indicating their presence and shape.
• This approach shows significant promise for predicting crack characteristics and assessing the residual life of materials.