Session: 17-01-01: Research Posters

Paper Number: 150981

150981 - Laser Vibrometry and Wavenumber Analysis Enabled Mechanical Properties Characterization for Additively Manufactured Thermoset Composites 

Thermoset materials have begun to be applied in additive composite manufacturing due to their ability to withstand high temperatures without losing structural integrity. Meanwhile, mechanical properties characterization of additive manufactured composites is critical for ensuring the materials' performance, reliability, and safety in manufacturing processes. However, traditional testing methods struggle to accurately characterize additive-manufactured composites due to challenges posed by curing processes, microstructural variability, anisotropic properties of thermoset materials, and the risk of damaging these materials during evaluation. 

This study presents a novel method that fuses noncontact guided wave sensing and wavenumber analysis for characterizing the mechanical properties of additive manufactured anisotropy thermoset composites. To develop this method, we established a guided wave sensing system, which used a piezoelectric actuator (PZT actuator) to generate guided waves in the panel and a laser Doppler vibrometer (LDV) integrated into a 3D robotic stage to acquire guided waves in a non-contact manner. By automatically moving the laser focus position and collecting guided wave signals by 2D grid scanning, our system was able to acquire a time-space wavefield. Due to the anisotropic behavior of the structure, the scanned time-space wavefield will contain a wealth of information about Guided waves propagating in all directions. To analyze the acquired wavefield and determine the material properties in different directions, we established a novel inverse method that fuses multidimensional Fourier transform and fast dispersion curve fitting based on an optimization algorithm. The multidimensional Fourier transform can change a time-space wavefield to a 2D wavenumber vector spectrum that reveals the frequency-wavenumber vector components of the acquired guided waves. By converting the coordinate system of the wavenumber vector spectrum from the Cartesian coordinate system to the cylindrical coordinate system and doing superimposing analysis to the spectrum by different frequencies, the frequency-wavenumber dispersion curves in different directions can be obtained. After regression of the experimental results using an optimization algorithm, the mechanical parameters of the material in each direction can be obtained. For proof of concept, we performed experiments using our method to measure the mechanical properties of a 300x 250x 8mm 3D printed thermoset material panel with reinforced carbon fiber. We showed that our system could successfully generate guided waves using a PZT actuator with a wideband (100kHz – 1MHz) chirp excitation signal modulated by a Hanning window. We also showed that our LDV integrated on a 3D robotic stage could acquire a time-space wavefield of guided waves in the testing sample. Moreover, using our wavefield analysis method, two material properties (Shear wave velocity and Poisson's ratio) were successfully determined. This experimental study proves the feasibility of our guided wave sensing system for characterizing the mechanical properties of additive-manufactured thermoset composites. We expect this research to enhance a noncontact and efficient method for characterizing multiple-type composites and monitoring their property changes when additive manufacturing.
 

Presenting Author: Bowen Cai Mississippi State University

Presenting Author Biography: Bowen Cai is a Ph.D. Candidate in Aerospace Engineering at Mississippi State University studying under Dr. Rani Sullivan and Dr. Zhenhua Tian. He is also a research assistant at the Advanced Composite Institute of MSU. His main research direction is acoustic nondestructive testing. He also explores the application of ultrasound and vibration technologies in various fields, including composites and biomaterials. Before pursuing his doctorate, Bowen conducted research in vibration control and finite element analysis of materials. He holds an M.S. in Mechanical Engineering from the University of Dayton and a B.S. in Mechanical Engineering from Tianjin University of Technology.

Authors:

Bowen Cai Mississippi State University
Hunter Watts Mississippi State University
Chuangchuang Sun Mississippi State University
Jiali Li Virginia Tech
Wayne Huberty Mississippi State University
Zhenhua Tian Virginia Tech