Open Access Open Access  Restricted Access Subscription Access

Investigating the Influence of Environmental Conditioning on Epoxy Resins at Quasistatic and High Strain Rates for Material Operating Limit

SAGAR M. DOSHI, NITHINKUMAR MANOHARAN, BAZLE Z. (GAMA) HAQUE, JOSEPH M. DEITZEL, JOHN W. GILLESPIE, JR.

Abstract


Epoxy resin-based composite panels used for armors may be subjected to a wide range of operating temperatures (-55°C to 76°C) and high strain rates on the order of 103-104 s-1. Over the life cycle, various environmental factors also affect the resin properties and hence influence the performance of the composites. Therefore, it is critical to determine the stress-strain behavior of the epoxy resin over a wide range of strain rates and temperatures for accurate multi-scale modeling of composites and to investigate the influence of environmental aging on the resin properties. Additionally, the characterization of key mechanical properties such as yield stress, modulus, and energy absorption (i.e. area under the stress-strain curve) at varying temperatures and moisture can provide critical data to calculate the material operating limits. In this study, we characterize mechanical properties of neat epoxy resin, SC-15 (currently used in structural armor) and RDL-RDC using uniaxial compression testing. RDL-RDC, developed by Huntsman Corporation, has a glass transition temperature of ~ 120°C, compared to ~ 85°C of SC-15. A split Hopkinson pressure bar is used for high strain rate testing. Quasistatic testing is conducted using a screw-driven testing machine (Instron 4484) at 10-3 s-1 and 10-1 s-1 strain rates and varying temperatures. The yield stress is fit to a modified Eyring model over the varying strain rates at room temperature. For rapid investigation of resistance to environmental aging, accelerated aging tests are conducted by immersing the specimens in 100°C water for 48 hours. Specimens are conditioned in an environmental chamber at 76 °C and 88% RH until they reach equilibrium. Tests are then conducted at five different temperatures from 0°C to 95°C, and key mechanical properties are then plotted vs. temperature. The results presented are an important step towards developing a methodology to identify environmental operating conditions for composite ground vehicle applications.


DOI
10.12783/asc36/35745

Full Text:

PDF

References


F. T. Wallenberger and P. A. Bingham, “Fiberglass and Glass Technology Energy-Friendly Compositions and Applications.â€

B. A. Gama and J. W. Gillespie, “Finite element modeling of impact, damage evolution and penetration of thick-section composites,†Int. J. Impact Eng., vol. 38, no. 4, pp. 181–197, Apr. 2011, doi: 10.1016/j.ijimpeng.2010.11.001.

“Department of Defense Test Method Standard - Environmental Enigineering Considerations and Laboratory Tests†MIL-STD-210G 2008.

J. L. Jankowsky, D. G. Wong, M. F. DiBerardino, and R. C. Cochran, “Evaluation of upper use temperature of toughened epoxy composites,†in ASTM Special Technical Publication, 1994, no. 1249, pp. 277–292, doi: 10.1520/stp15381s.

“DOT/FAA/AR-01/40 Determination of Temperature/ Moisture Sensitive Composite Properties,†2001.

J.W. Gillespie (contributing author), “Composite Armored Vehicle Advanced Technology Demonstrator (CAV-ATD) Design Guide,†in United Defense, L.P Ground Systems Division, Contract DAAE97-94-C-R011, August, 1999.

T.L. Pike, G.E. Thomas, J.W. Gillespie, J. Florence “MANTECH CAV Demonstration of Advanced Manufacturing Technologies for Ground Combat Vehicles,†November, 2000.

S. Tamrakar, R. Ganesh, S. Sockalingam, B. Z. Haque, and J. W. Gillespie, “Experimental Investigation of Strain Rate and Temperature Dependent Response of an Epoxy Resin Undergoing Large Deformation,†J. Dyn. Behav. Mater., vol. 4, pp. 114–128, 1234, doi: 10.1007/s40870-018-0144-8.

W. Chen and B. Song, Split Hopkinson (Kolsky) bar: design, testing and applications. 2010.

C. R. Siviour and J. L. Jordan, “High Strain Rate Mechanics of Polymers: A Review,†doi: 10.1007/s40870-016-0052-8.

R. Haward, The physics of glassy polymers. 2012.

R. S. Hoy and M. O. Robbins, “Strain hardening in polymer glasses: Limitations of network models,†Phys. Rev. Lett., vol. 99, no. 11, p. 117801, Sep. 2007, doi: 10.1103/PhysRevLett.99.117801.

J. A. Roetling, “Yield stress behaviour of poly(ethyl methacrylate) in the glass transition region,†Polymer (Guildf)., vol. 6, no. 11, pp. 615–619, Nov. 1965, doi: 10.1016/0032-3861(65)90056-X.

H. Panda, Epoxy resins technology handbook (manufacturing process, synthesis, epoxy resin adhesives and epoxy coatings). 2019.

S. Glasstone, K. Laidler, and H. Eyring, “The theory of rate processes; the kinetics of chemical reactions, viscosity, diffusion and electrochemical phenomena,†1941.


Refbacks

  • There are currently no refbacks.