Self‐Reporting Fiber‐Reinforced Composites That Mimic the Ability of Biological Materials to Sense and Report Damage

Abstract

Sensing of damage, deformation, and mechanical forces is of vital importance in many applications of fiber-reinforced polymer composites, as it allows the structural health and integrity of composite components to be monitored and microdamage to be detected before it leads to catastrophic material failure. Bioinspired and biomimetic approaches to self-sensing and self-reporting materials are reviewed. Examples include bruising coatings and bleeding composites based on dye-filled microcapsules, hollow fibers, and vascular networks. Force-induced changes in color, fluorescence, or luminescence are achieved by mechanochromic epoxy resins, or by mechanophores and force-responsive proteins located at the interface of glass/carbon fibers and polymers. Composites can also feel strain, stress, and damage through embedded optical and electrical sensors, such as fiber Bragg grating sensors, or by resistance measurements of dispersed carbon fibers and carbon nanotubes. Bioinspired composites with the ability to show autonomously if and where they have been damaged lead to a multitude of opportunities for aerospace, automotive, civil engineering, and wind-turbine applications. They range from safety features for the detection of barely visible impact damage, to the real-time monitoring of deformation of load-bearing components.

Microcapsule encapsulated with leuco dye as a visual sensor for concrete damage indicationviacolor variation

“…A series of visual damage strategies based on visualization materials had been developed for damage indication. [10][11][12][13][14] Dye-lled hollow glass ber [15][16][17] was used to indicate mechanic damages for polymers, but it cannot be applied to the surfaces of complex structures because of its slender shape. The microcapsule-based visualization sensor solves these problems better.…”

Soft Electronic Skin for Multi‐Site Damage Detection and Localization

“…Recent efforts have focused on more scalable methods based on thin‐film approaches that utilize visual inspection or ultrasonic techniques. Examples include the use of dye penetrants or mechanically induced color change through the use of specific chemical functional groups that undergo mechanochemical reactions . Despite their promise for certain monitoring conditions, these techniques often result in a limited visual signal and can require controlled lighting conditions to increase reliability .…”

Microcapsule‐Based Visualization Smart Sensors for Damage Detection: Principles and Applications

“…Visual sensors mainly include two types of film and microcapsule . The film visualization materials can only be applied to the surfaces as structural coatings .…”