Electroluminescent strain sensing on carbon fiber reinforced polymer

The present paper demonstrates an inexpensive and less labor-intensive machine vision-based strain and damage visualization technique compared to traditional carbon fiber reinforced polymer material inspection methods. This technique is used to characterize the fracture and failure properties upon progressive axial loading in textile carbon fiber reinforced polymer (CFRP) lamina with non-intrusive smart electroluminescent (EL) integration. The smart EL structure utilizes CFRP's unique conductive and piezoresistive properties to visualize deformation and cracks through brightness change. Two fiber orientations (+/- 45 degrees and 0 degrees/90 degrees) of twill-weave CFRP lamina are fabricated according to a modified ASTM D3039 for linear and fatigue loading in uniaxial mechanical tests to analyze both fiber and matrix-induced EL responses. The EL-strain visualization method is validated with standardized digital image correlation (DIC) utilizing the natural speckling pattern of the EL CFRP lamina. The axial EL-strain results for both static and cyclic loading highly agree with the strain extracted planar conventional DIC strain field on standard and damaged CFRP samples in terms of spatial resolution and sensitivity. This novel strain and damage visualization method aims to be a portable, low-cost, and real-time alternative to non-destructive testing methods commonly used in the composite industry. Instead of periodic checkups, EL architecture allows for real-time strain and damage visualization of composite structure.

Automated summary

This paper presents a machine vision-based strain and damage visualization technique using smart electroluminescent integration for carbon fiber reinforced polymer (CFRP) material inspection. The technique allows for real-time visualization of deformation and cracks in CFRP lamina during progressive axial loading, providing a portable and low-cost alternative to traditional non-destructive testing methods.