Title: Design of an Automated Ultrasonic Scanning System for In-situ Composite Cure Monitoring and Defect Detection

Authors: Tyler B. Hudson, Frank L. Palmieri, T. Bryce Abbott, Jeffrey P. Seebo, and Eric R. Burke

DOI: 10.33599/nasampe/s.19.1523

Abstract: The preliminary design and development of an automated ultrasonic scanning system for in-situ composite cure monitoring and defect detection in the high temperature environment of an oven was completed. This preliminary design is a stepping stone to deployment in the high temperature and high pressure environment of an autoclave, the primary cure method of aerospace grade thermoset composites. Cure monitoring with real-time defect detection during the process could determine when defects form and how they move. In addition, real-time defect detection during cure could assist validating physics-based process models for predicting defects at all stages of the cure cycle. A physics-based process model for predicting porosity and fiber waviness originating during cure is currently under development by the NASA Advanced Composites Project (ACP).

For the design, an ultrasonic contact scanner is enclosed in an insulating box that is placed inside an oven during cure. Throughout the cure cycle, the box is nitrogen-cooled to approximately room temperature to maintain a standard operating environment for the scanner. The composite part is mounted on the outside of the box in a vacuum bag on the build/tool plate. The build plate is attached to the bottom surface of the box. The scanner inspects the composite panel through the build plate, tracking the movement of defects introduced during layup and searching for new defects that may form during cure. The focus of this paper is the evaluation and selection of the build plate material and thickness. The selection was based on the required operating temperature of the scanner, the cure temperature of the composite material, thermal conductivity models of the candidate build plates, and a series of ultrasonic attenuation tests. This analysis led to the determination that a 63.5 mm thick build plate of borosilicate glass would be utilized for the system. The borosilicate glass plate was selected as the build plate material due to the low ultrasonic attenuation it demonstrated, its ability to efficiently insulate the scanner while supporting an elevated temperature on the part side of the plate, and the availability of a 63.5 mm thick plate without the need for lamination.

References: [1] Antonucci, V., Giordano, M., Cusano, A., Nasser, J. & Nicolais, L., "Real time monitoring of cure and gelification of a thermoset matrix." Composites Science and Technology 66 (2006): 3273-3280. [2] Jeong, H., "Effects of voids on the mechanical strength and ultrasonic attenuation of laminated composites." Journal of Composite Materials 31 (1997): 276-292. [3] Nixdorf, K. & Busse, G., "The dielectric properties of glass-fibre-reinforced epoxy resin during polymerisation." Composites Science and Technology 61 (2001): 889-894. [4] Maffezzoli, A., Quarta, E., Luprano, V., Montagna, G. & Nicolais, L., ""Cure monitoring of epoxy matrices for composites by ultrasonic wave propagation."" Journal of Applied Polymer Science 73 (1999): 1969-1977. [5] Lionetto, F. & Maffezzoli, A., "Monitoring the cure state of thermosetting resins by ultrasound." Materials 6 (2013): 3783-3804. [6] Lionetto, F., Rizzo, R., Luprano, V. & Maffezzoli, A., "Phase transformations during the cure of unsaturated polyester resins." Materials Science and Engineering: A 370 (2004): 284-287. [7] Hudson, T. B. & Yuan, F. G., "Automated in-process cure monitoring of composite laminates using a guided wave-based system with high temperature piezoelectric transducers." Journal of Nondestructive Evaluation, Diagnostics and Prognostics of Engineering Systems 1 (2018): 021008. [8] Hudson, T.B., "Real-time Cure Monitoring of Composites Using a Guided Wave-based System with High Temperature Piezoelectric Transducers, Fiber Bragg Gratings, and Phase-shifted Fiber Bragg Gratings." Dissertation, Doctor of Philosophy Aerospace Engineering, North Carolina State University, (2017). [9] Hudson, T. B., Auwaijan, N. & Yuan, F. G., "Guided wave-based system for real-time cure monitoring of composites using piezoelectric discs and fiber Bragg gratings/phase-shifted fiber Bragg gratings." Journal of Composite Materials (2018): 0021998318793512. [10] Gholizadeh, S., "A review of non-destructive testing methods of composite materials." Procedia Structural Integrity 1 (2016): 50-57. [11] Garnier, C., Pastor, M., Eyma, F. & Lorrain, B., "The detection of aeronautical defects in situ on composite structures using Non Destructive Testing." Composite Structures 93 (2011): 1328-1336. [12] Chen, J., Hoa, S., Jen, C. & Wang, H., "Fiber-optic and ultrasonic measurements for in-situ cure monitoring of graphite/epoxy composites." Journal of Composite Materials 33 (1999): 1860-1881. [13] Stone, D. & Clarke, B., "Ultrasonic attenuation as a measure of void content in carbon-fibre reinforced plastics." Non-destructive Testing 8 (1975): 137-145. [14] Baste S., "Determination of elastic properties by an ultrasonic technique." Proceedings of the 12th International Conference on Composite Materials, Paris. 1999. [15] Balmer, R. T. Modern engineering thermodynamics-textbook with tables booklet. Academic Press, 2010. [16] Ginzel, E., Ginzel, R. & Brothers, G., "Ultrasonic properties of a new low attenuation dry couplant elastomer." Ginzel brothers & associates Ltd (1994).

Conference: SAMPE 2019 - Charlotte, NC

Publication Date: 2019/05/20

SKU: TP19--1523

Pages: 12

Price: FREE