Session: 01-03-01: Advanced Manufacturing for Aerospace Structures

Paper Number: 107360

107360 - Lightweight Composites With 3d Printed Sensors for Real-Time Damage Detection 

Fiber-reinforced composites have been used for a variety of applications, such as aerospace, civil, and mechanical infrastructures for the last two decades. Although composites are widely used and accepted across various industries, concerns still remain about the structural integrity of composite materials that are subject to fatigue and possible impact loading. Damage accumulation in composites is progressive in nature, with damage that initiates in microscale matrix cracks that lead to delamination and even fiber fracture. Furthermore, the failure mechanisms of composite laminates are more complicated and damage detection is challenging. Current damage identification strategies often rely on monitoring the quality of engineering infrastructure over time with periodically spaced measurements. These can be costly and inefficient when the structure is healthy, but scheduled maintenance is required to ensure the infrastructure is undamaged. Therefore, it is critical to develop reliable and accurate damage detection technologies to improve the structural durability and operational safety of lightweight composite laminates for industry applications.

The goal of this paper is to describe the design, development, manufacture, and characterization of a novel type of fiber-reinforced composite laminates with embedded nanocomposite-based strain sensors for potential real-time load monitoring and damage detection. The fiber reinforced composite laminate will be Kevlar fiber and an epoxy mixture, with a nanocomposite of carbon nanotubes (CNTs) and the same epoxy mixture. Due to the extremely high electrical conductivity, the dispersion of 1-2 wt.% CNTs can significantly improve the electrical conductivity of epoxies in structural composites, leading to piezoresistive-based sensing capabilities for load sensing and damage detection. CNT nanoparticles and structural epoxy will be first mixed using the high-shear mixer system, then transferred to a syringe for 3D printing. The CNT-based nanocomposite will be 3D printed onto a strip of Kevlar fiber by direct ink writing (DIW) at a speed of 1 mm/s and 30 kPa in a strain sensor pattern with two terminals. Copper wires will be placed on the terminals for load sensing applications before the 3D printed nanocomposites are fully cured. High-quality structural composites will be manufactured by wet layup of 6 layers of Kevlar fiber, with the sensor embedded within. The composite will be fully cured in a thermal oven for 2 hours at 190°C. The manufactured composite laminates with embedded nanocomposite sensors will be characterized under uniaxial tension load to understand their in-situ sensing capability. To quantify the piezoresistive behavior, relative resistance change ∆𝑅⁄𝑅𝑜 (where Ro is the initial resistance at the unloaded condition) will be recorded while applying quasi-static tension at different strains in a cyclic manner. The mechanical properties and piezoresistive functionality of the composites will be determined as the samples undergo deformation. The corresponding piezoresistive change happening at the same time will be used as a damage identification feature.

Presenting Author: Yingtao Liu University of Oklahoma

Presenting Author Biography: Dr. Yingtao Liu is an Associate Professor at the University of Oklahoma.

Authors:

Daniel Fitzpatrick University of Oklahoma
Christopher Billings University of Oklahoma
Yingtao Liu University of Oklahoma