# Printed Crack Detection Sensors for SHM Based on Direct Ink Write Additive Manufacturing

## TL;DR

This paper introduces a new method for detecting structural cracks using printed sensors made with silver ink and additive manufacturing, showing high reliability and precision.

## Contribution

The novelty lies in combining Direct Ink Write manufacturing with adaptive sensor design for fatigue crack detection.

## Key findings

- The sensors achieved a 5% tolerance for batch production repeatability.
- Damage size estimation had less than 1 mm precision over 30 mm crack length.
- Sensors remained fully functional for up to 1.5 million fatigue cycles.

## Abstract

The following paper aims to provide the results of an innovative structural crack detection technique using printed adaptive sensors. They were manufactured using conductive ink with silver microparticles and polymer insulators. The technique leveraged the unique properties of Direct Ink Write additive manufacturing combined with domain knowledge in the field of technical condition monitoring. The goal was to achieve high sensitivity and precision in detecting fatigue-crack-induced changes in structural components. The sensors’ fabrication repeatability, output stability, and crack detection capabilities were investigated. Based on preliminary measurements of the sensors’ output characteristics, the analyzed data showed that a tolerance in the range of 5% can be obtained for batch production. Damage size estimation using this new crack gauge during a fatigue crack growth test was high compared to the reference, with less than 1 mm precision over 30 mm of crack length. Throughout the fatigue test of up to 1.5 million cycles, all CCPSs remained fully functional, with no failure-related changes in their output signal patterns. The proposed sensor has proven its reliability for the detection of fatigue cracks and propagation monitoring and is a good alternative to other SHM technologies for this purpose.