Title: Multifunctional Films for Fusion Bonding and Structural Health Monitoring of Thermoplastic Composite Joints

Authors: H. Frederick, W. Lia, W. Sands, E. Tsai and G. Palardy

DOI: 10.33599/nasampe/s.20.0032

Abstract: Ultrasonic welding is a promising method to quickly bond thermoplastic composite parts. In this process, a thermoplastic film, called an “energy director”, is placed between two pieces of composite materials, and melted during the welding process to facilitate bonding. This study seeks to develop a multifunctional energy director suitable for three purposes: 1) ultrasonic welding, 2) structural health monitoring (SHM) via electrical resistance measurements, and 3) heating element for disassembly and repair of the damaged bond. Various materials and manufacturing methods were investigated to develop multifunctional films: 1) magnetic or conductive nanoparticles deposited onto polymer films, and 2) multi-walled carbon nanotubes (MWNTs) dispersed into polymers. The latter was selected as a promising candidate because of its ease of manufacturability through compression molding and its compatibility with the welding process. The thermo-electrical and electro-mechanical behavior of compression molded films containing up to 20 wt% MWNT in a polypropylene (PP) matrix was assessed via a sourcemeter and dynamic mechanical analyzer. To demonstrate multifunctionality, glass fiber/PP specimens were ultrasonically welded with the MWNT/PP films as energy directors. While the multifunctional films reduced lap shear strength by up to 10%, they did not significantly affect the welding process. Moreover, welded specimens with the MWNT/PP films were successfully tested under cyclic bending for SHM through resistance measurements.

References: 1. Yousefpour A, Hojjati M, Immarigeon J-P. "Fusion Bonding/Welding of Thermoplastic Composites". Journal of Thermoplastic Composite Materials. 2004;17(4):303-41.DOI:10.1177/0892705704045187 2. Palardy G, Shi H, Levy A, Le Corre S, Fernandez Villegas I. "A study on amplitude transmission in ultrasonic welding of thermoplastic composites". Composites Part A: Applied Science and Manufacturing. 2018;113:339-49.DOI:10.1016/j.compositesa.2018.07.033 3. Villegas IF. "In situ monitoring of ultrasonic welding of thermoplastic composites through power and displacement data". Journal of Thermoplastic Composite Materials. 2015;28(1):66-85. DOI:10.1177/0892705712475015 4. Goto K, Imai K, Arai M, Ishikawa T. "Shear and tensile joint strengths of carbon fiber-reinforced thermoplastics using ultrasonic welding". Composites Part A: Applied Science and Manufacturing. 2019;116:126-37.DOI:10.1016/j.compositesa.2018.10.032 5. Li Y, Arinez J, Liu Z, Hwa Lee T, Fan H-T, Xiao G, et al. "Ultrasonic Welding of Carbon Fiber Reinforced Composite With Variable Blank Holding Force". Journal of Manufacturing Science and Engineering. 2018;140(9).DOI:10.1115/1.4040427 6. Zhao T, Palardy G, Villegas IF, Rans C, Martinez M, Benedictus R. "Mechanical behaviour of thermoplastic composites spot-welded and mechanically fastened joints: A preliminary comparison". Composites Part B-Engineering. 2017;112:224-34.DOI:10.1016/j.compositesb.2016.12.028 7. Zhao T, Broek C, Palardy G, Villegas IF, Benedictus R. "Towards robust sequential ultrasonic spot welding of thermoplastic composites: Welding process control strategy for consistent weld quality". Composites Part A: Applied Science and Manufacturing. 2018;109:355-67.DOI:10.1016/j.compositesa.2018.03.024 8. Shimada S, Tanaka H, Hasebe K, Hayashi N, Ochi Y, Matsui T, et al. "Ultrasonic welding of polymer optical fibres onto composite materials". Electronics Letters [Internet]. 2016; 52(17):[1472-4 pp.].DOI:10.1049/el.2016.0905 9. Ochôa P, Villegas IF, Groves RM, Benedictus R. "Diagnostic of manufacturing defects in ultrasonically welded thermoplastic composite joints using ultrasonic guided waves". NDT & E International. 2019;107:102126.DOI:10.1016/j.ndteint.2019.102126 10. Siddique S, Park JG, Andrei P, Liang R. "M3D aerosol jet printed buckypaper multifunctional sensors for composite structural health monitoring". Results in Physics. 2019;13. DOI:10.1016/j.rinp.2019.02.030 11. DeGraff J, Liang R, Le MQ, Capsal J-F, Ganet F, Cottinet P-J. "Printable low-cost and flexible carbon nanotube buckypaper motion sensors". Materials & Design. 2017;133:47-53.DOI:10.1016/j.matdes.2017.07.048 12. Jang S-H, Park Y-L. "Carbon nanotube-reinforced smart composites for sensing freezing temperature and deicing by self-heating". Nanomaterials and Nanotechnology. 2018;8.DOI:10.1177/1847980418776473 13. Costa P, Carvalho MF, Correia V, Viana JC, Lanceros-Mendez S. "Polymer Nanocomposite-Based Strain Sensors with Tailored Processability and Improved Device Integration". ACS Applied Nano Materials. 2018;1(6):3015-25.DOI:10.1021/acsanm.8b00647 14. Farahani RD, Janier M, Dubé M. "Conductive films of silver nanoparticles as novel susceptors for induction welding of thermoplastic composites". Nanotechnology. 2018;29(12):125701.DOI:10.1088/1361-6528/aaa93c 15. Palardy G, Villegas IF. "On the effect of flat energy directors thickness on heat generation during ultrasonic welding of thermoplastic composites". Composite Interfaces. 2016;24(2):203-14. DOI: 10.1080/09276440.2016.1199149

Conference: SAMPE 2020 | Virtual Series

Publication Date: 2020/06/01

SKU: TP20-0000000032

Pages: 15

Price: FREE