Structural health monitoring (SHM) has been employed for damage detection of aerospace structures. SHM uses a network of sensors that are instrumented at critical locations in aerospace structure for seamless monitoring of the critical structural members. In particular, there are sensor technologies developed to be used in SHM framework for delamination detection of FRP (e.g., fiber Bragg gratings and nanocomposites). However, these advanced sensors still suffer from dependency on an external power source. In particular, for cases where a large network of sensors is instrumented, power consumption by the sensor network may overwhelm the entire aerospace structural systems. To overcome the issue due to energy dependency of the state-of-the-art sensor technologies, it is needed to develop self-powered sensors used in SHM framework, which can detect delamination in FRP of aerospace structures. The freed-up power can help improve mission success of aerospace structure by increasing airtime.In this research, we suggest a self-powered strain sensor, which is built with multifunctional mechanoluminescent-optoelectronic (MLO) composites, and validate its capability to detect delamination in FRP. First, an MLO-based self-powered strain sensor is fabricated using two functional materials: mechano-luminescent (ML) copper-doped zinc sulfide (ZnS:Cu)-based elastomeric composites and mechano-optoelectronic (MO) poly(3-hexylthiophene) (P3HT)-based thin films. Second, the MLO sensor is then subjected to uniaxial sinusoidal cyclic loadings using a load frame and tested by varying strains and strain rates to validate its self-powered strain sensing capability. A direct current (DC) response is recorded during the cyclic loadings. Last, the MLO sensor is placed on one side of an FRP test coupon, where pre-crack is formed to initiate delamination, to prepare test specimen. The specimen is subjected to a cyclic loading using 3-point bending test setup, and various test cases are conducted by varying strains and strain rates. The MLO sensor on the FRP test coupon generates DC sensor signal, which is measured using a digital multimeter, to be compared to parameters for assessing significance of delamination.

Delamination Detection in Fiber-Reinforced Polymers Using Mechanoluminescence-Optoelectronic Strain Sensor

Paper Proceedings: https://asmedigitalcollection.asme.org/SMASIS/SMASIS2021/volume/85499

ASME 2021 Smart Materials, Adaptive Structures and Intelligent Systems (SMASIS2021)

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