Session: 01-06-02: New Advances in Acoustics and Vibration: AI and Machine Learning, New Methods and Materials

Paper Number: 139660

139660 - Acoustic Emission Analysis and Source Localization With Pencil Lead Breaks on Graphene-Reinforced Epoxy Specimens 

Graphene-reinforced epoxy materials have become popular in engineering applications because of their advanced mechanical properties such as lightweight and high strength. When introducing composite materials into structures, it has also brought great interest in how to monitor the functionality of the materials and identify material failure in real time. Therefore, the structure health monitoring of such materials has received great attention. Especially, engineers are working on understanding the structure of composite materials and whether the mechanical properties and failure behavior could change when the contents vary in the composite materials. There is a broad range of non-destructive testing methods, such as ultrasonic and thermography tests. In our study, we have chosen the acoustic emission (AE) method because it could be conducted with a minimal number of sensors and provide real-time feedback with a limited signal processing time. The goal of the proposed project was to validate the efficiency of using the AE method to identify the location of failure(s) at the graphene-reinforced structure. Sound source localization algorithms have been widely used with AE technology to identify the location of defects and cracks. It usually collects the time of arrival (TOA) or time differences of arrival (TDOA) at the sensor arrays, and calculates the location of the sound source, saying where the AE is generated by cracks, with the geometry information of the structure. In this project, three different types of samples were prepared, on epoxy with 1%, 2%, and 3% graphene-reinforced. The samples were shaped based on the ASME tensile test specimen standard. During the experiments, two sensors were placed on both ends of a sample, and a pencil lead break was used to produce AE signals at multiple locations in between the sensors on the sample. After each pencil lead break, the time instances of the first hit signal at each sensor were recorded. The TDOA between the two sensors was recorded. Because of the geometric setup of the samples, we simplified it to a two-dimensional problem. With the prior information of the breaking location measured, the TDOAs were used to identify the speed of sound traveling in the sample. Ten trials at multiple pencil breakpoints were conducted and the accuracy of AE source localization was evaluated. The mean and standard deviation values were plotted. Results of different samples with 1%, 2%, and 3% graphene content were compared. We also developed a numerical modal for the test and the results were compared and discussed.  Future work of the project will be to conduct tensile tests on the samples and evaluate the AE localization effectiveness in monitoring fracture location in real-time.

Presenting Author: Michael Ewles University of Michigan – Flint

Presenting Author Biography: Michael Ewles is currently undergraduate student in the mechanical engineering program at College of Innovation Technology, University of Michigan – Flint.

Authors:

Michael Ewles University of Michigan – Flint
Griffin Rousseau University of Michigan – Flint
Linda Zhu University of Michigan - Flint
Je-Heon Han Tech University of Korea
Olanrewaju Aluko University of Michigan – Flint