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Fracture Analysis of Rubber Toughened Additively Manufactured Thermosets

MEGAN SHEPHERD, KAMRAN MAKARIAN, GIUSEPPE PALMESE, NICHOLAS BRUNSTAD, LESLIE LAMBERSON

Abstract


This study explores the role of rubber toughening on the dynamic fracture behavior of additively manufactured (AM) high-performance thermosetting polymers formed through digital light processing (DLP). Using DLP to create these polymers allows for rapid, agile manufacturing of prototypes meeting the lightweight and building speed requirements of relevance to military mission applications. This method also provides flexibility in part complexity while maintaining relatively high isotropy compared to traditional AM techniques. Previous work has demonstrated a dependence of these DLP specimens on print layer orientation and loading rate, prompting further investigation into other manufacturing parameters to improve toughness [1]. This study examines the role of rubber toughening on the quasi-static and dynamic fracture behavior of bis-GMA thermosets. Current literature largely reports on quasi-static behavior of DLP specimens, although dynamic conditions are more applicable to many realistic loading scenarios and extreme environments often seen in defense applications. Dynamic experiments leverage a unique long bar striker device that impacts a specimen opposite a pre-crack, sending a stress-wave driven load to initiate a dynamic Mode-I (opening) fracture event. Full-field displacement data ahead of the propagating crack is obtained using ultra high-speed imaging combined with 2D digital image correlation (DIC). An elastodynamic solution following the principles of dynamic fracture mechanics extracts the stress intensity factor (SIF) using a least squares fit at crack initiation and a Newton-Raphson scheme for crack propagation. The rubber toughened thermosets in this study exhibited a rate dependence in fracture toughness with the quasi-static SIF being 1.20 MPa and the dynamic SIF being 0.41 MPa .


DOI
10.12783/asc36/35808

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References


Brunstad, Nicholas, et al. “Dynamic and Quasi-Static Fracture Behavior of Two AdditivelyManufactured Thermoset Resins.” Polymer Testing, in preparation (2021).

J. R. C. Dizon, A. H. Espera, Q. Chen, and R. C. Advincula, 2018. “Mechanicalcharacterization of 3D-printed polymers,” Addit. Manuf. vol. 20 pp. 44–67.

J. Li, S. Yang, D. Li, and V. Chalivendra, 2018. “Numerical and experimental studies ofadditively manufactured polymers for enhanced fracture properties,” Eng. Fract. Mech. vol.204, pp. 557–569.

Aznarte, E.; Ayranci, C.; Qureshi, A. J. (2020). Digital light processing (DLP): Anisotropictensile considerations, Solid Freeform Fabrication 2017: Proceedings of the 28th AnnualInternational Solid Freeform Fabrication Symposium - An Additive Manufacturing Conference,SFF 2017, pp. 413–425

M. Monzón, Z. Ortega, A. Hernández, R. Paz, and F. Ortega. 2017 “Anisotropy ofphotopolymer parts made by digital light processing,” Materials, vol. 10, no. 1, pp. 1–15.

N. J. Brunstad. 2021. “A Study of Layer Orientation on the Fracture Behavior of TwoAdditively Manufactured Resins.” Colorado School of Mines Thesis.

Kinloch, A.J., et al. “Deformation and Fracture Behaviour of a Rubber-Toughened Epoxy: 1.Microstructure and Fracture Studies.” Polymer, vol. 24, no. 10, Oct. 1983, pp. 1341–1354.,doi:10.1016/0032-3861(83)90070-8.

Grous, Alexander Thomas, and Giuseppe R. Palmese. “Toughening Bimodal Vinyl EsterBlends Using Bio-Rubber Monomers.” Drexel University, 2011.

Pearson, R. A. “ASC Symposium Series.” American Chemical Society, Introduction to theToughening of Polymers, 2000, pp. 1–12.

M. A. Sutton, J.-J. Orteu, and H. W. Schreier. 2009. “Digital Image Correlation (DIC),” inImage Correlation for Shape, Motion and Deformation Measurements: Basic Concepts,Theoryand Applications. Springer US pp. 1–37.

M. S. Kirugulige, H. V. Tippur, and T. S. Denney. 2007. “Measurement of transientdeformations using digital image correlation method and high-speed photography: applicationto dynamic fracture,” Appl. Opt., vol. 46, no. 22, pp. 5083–5096.

R. J. Sanford. 1980. “Application of the least-squares method to photoelastic analysis,” Exp.Mech., vol. 20, no. 6, pp. 192–197.

S. Yoneyama, Y. Morimoto, M. Takashi. 2006. “Automatic Evaluation of Mixed‐mode StressIntensity Factors Utilizing Digital Image Correlation," Strain, vol. 42, no. 1, pp. 21-29.

L. S. Spencer. 2017. “A Hybrid Experimental-Computational Approach for the Analysis ofDynamic Fracture" Drexel University Thesis.

G. C. Sih, P. C. Paris, and G. R. Irwin. 1965. “On cracks in rectilinearly anisotropic bodies,”Int. J. Fract. Mech., vol. 1, no. 3, pp. 189–203.

M. S. Kirugulige and H. V. Tippur. 2009. “Measurement of Fracture Parameters for a Mixed-Mode Crack Driven by Stress Waves using Image Correlation Technique and High-SpeedDigital Photography,” Strain, vol. 45, no. 2, pp. 108–122.

C. Liu, A. J. Rosakis, and M. G. Stout. 2001. “Dynamic Fracture Toughness of a UnidirectionalGraphite/Epoxy Composite,” Proceedings of the Symposium on “Dynamic Effects in CompositeStructures”, ASME 2001 International Mechanical Engineering Congress & Exposition, NewYork, NY, November 11-18, 2001. http://lib-www.lanl.gov/la-pubs/00818425.pdf.

Xu, Shi-Ai, and Xiao-Xue Song. “Introduction to Rubber Toughened Epoxy Polymers.”Handbook of Epoxy Blends, 29 June 2017, pp. 3–28., doi:10.1007/978-3-319-40043-3_1.


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