Multifunctional Fiber-Reinforced Polymer Composites for Damage Detection and Memory

Abstract

Self-structural health monitoring (SHM) functionalities for fiber-reinforced polymer composites have become highly sought after to ensure the structural safety of newly advancing components in the automotive, civil, mechanical, and aerospace industries. This paper introduces a self-damage detection and memory (SDDM) hybrid composite material, where the structural carbon fiber tow is transformed into a piezoresistive sensor network, and the structural glass fiber operates as electrical insulation. In this study, SDDM specimens were fabricated, and tensile and impact tests were performed. The tensile tests of SDDM specimens find two distinct loading peaks: first where the carbon fiber fails, and second where the glass fiber fails. A linear correlation was observed between the carbon fiber resistance and composite strain up to a threshold, beyond which a sharp nonlinear increase in resistance occurred. The resistance then approached infinity, coinciding with the first loading peak and failure of the carbon fiber elements. This demonstrates the potential for a damage early warning threshold. Additionally, the effect of stitching the sensor tow in a zig-zag pattern over a large area was investigated using tailored fiber placement (TFP) of 1-loop, 3-loop, and 5-loop specimens. Tensile testing found that increasing the number of loops improved the sensor’s accuracy for strain sensing. Furthermore, impact tests were conducted, and as the impact energy progressively increased, the sensor resistance permanently increased. This illustrates a capability for self-memory of microdamage throughout the life cycle of the structure, potentially useful for predicting the remaining life of the composite.

Low-cost sensor-based damage localization for large-area monitoring of FRP composites

“…The mechanical properties may be moderately affected as the carbon fiber volume fraction increases. In previous work, the authors found both Young's modulus and ultimate strength to slightly increase [45]. For composite applications with fine-tuned mechanical properties, it is advised to include the carbon fiber sensor volume in calculations.…”

“…In previous work, the authors presented a self-SHM system for FRP composites, where the structural fabric itself is transformed into a piezoresistive sensor network [45]. The study used a hybrid glass fiber and carbon fiber fabric, where the structural glass fiber was also employed for its electrical insulation.…”

Damage localization in large-area FRP composites using a parallel array of self-sensing carbon fiber tows

“…In a previous work, the authors presented a self-structural health monitoring system for FRP composites, where the structural fabric itself is transformed into a piezoresistive sensor network. 24 In the study, a hybrid glass fiber and carbon fiber fabric was used, where the structural glass fiber was also employed for its electrical insulation. The sensor, composed of a single carbon fiber tow, is located within an area of interest and is shown to provide continuous in situ monitoring of that specific region.…”