Development of TPU/CNPs flexible composite strain sensors using Additive Manufacturing (AM) for Structural Health Monitoring (SHM) of aerospace components

Additive Manufacturing (AM) or 3D printing, is a rapid prototyping fabrication technique that ensures the layer by layer deposition of material on any custom rigid or flexible substrate. Different materials, including polymers, metals, ceramics & composites, are used to develop 3D objects without the wastage of material as conventional subtractive techniques like CNC cutting, and milling. Different researchers and industrialists are now working on 3D printing of composite materials for complex structures and rapid prototyping. This research involves the development of flexible polymeric strain sensors using 3D printing to develop smart composite materials. TPU/CNPs solution to 3D print linear strain sensors with the dimensions of 13mmx10mmx0.8mm using self-developed Direct Ink Write (DIW) 3D printing system on Polycarbonate flexible substrate with the thickness of 122µm. Sensors are deposited on GFRP flexural specimens to study the behavior of the strain gauges under dynamic loadings. The 4-point bend test following ASTM standard D7264 employs to determine real-time strain changes under bending conditions. Wheatstone bridge operates to detect theelectromechanical response under different loading scenarios. Arduino Microcontroller utilizes as a Data Acquisition System (DAQ) for logging real-time resistance response of the sensor. Specimens are subject to bend up to fracture, which helps us determine the model's real-time behavior under different loadings scenarios for Structural Health Monitoring (SHM). Images of the fractured surface taken using a microscope enable us to determine the fracture mode and the specimen's behavior under a specified loading scenario, which is essential for on-line Structural Health Monitoring (SHM).