Influence of Load Type and Stress Gradient on Flexural Strength of Epoxy Resin Polymeric Material
Publication: Journal of Aerospace Engineering
Volume 27, Issue 1
Abstract
A piecewise-linear parametric uniaxial stress-strain approach has been used to obtain the nonlinear moment curvature response based on strain compatibility in bending for epoxy resin materials. It has been shown that the direct use of tension and compression stress-strain models underestimates the flexural strength of epoxy resin materials in a three-point bending (3PB) setup. An analytical and experimental investigation is conducted to better evaluate the degree of flexural overstrength for epoxy resin material. Four-point bending (4PB) and a round plate (RP) supported on three symmetrically arranged pivot points on a circle are chosen. An algorithm is developed to obtain the load-deflection response of the 4PB and RP samples from the nonlinear moment curvature curve. Small-sized 3PB tests are conducted to examine the size effects on the flexural response. The experimental nonlinear load-deflection responses obtained in the various load arrangements are satisfactorily simulated through the developed algorithm. The simulations and experiments reveal that the ratio of the experimental flexural strength to that obtained through simulation (flexural overstrength factor) in 4PB is higher than the corresponding values in 3PB and the round panel. The conservative value of 1.14 could be used as the flexural overstrength factor for epoxy resin materials in analysis and design.
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Acknowledgments
The authors gratefully acknowledge the support for this research by the Aerospace and Defense Institute for Arizona, Science Foundation Arizona (SFAz), and Vice President for Research, Dr. Gary Greenburg (Agreement No. SRG 0443-10). The authors also acknowledge Honeywell Aerospace and Project Managers Mr. Griff Kinsinger and Mr. Rob Murray for equal cost sharing in this project.
References
ARAMIS 5.4.1 [Computer software]. Braunschweig, Germany, GOM.
ASTM. (2010a). “Standard test method for flexural properties of unreinforced and reinforced plastics and electrical insulating materials.” D790-10, West Conshohocken, PA.
ASTM. (2010b). “Standard test method for flexural properties of unreinforced and reinforced plastics and electrical insulating materials by four-point bending.” D6272-10, West Conshohocken, PA.
Bažant, Z. P., and Chen, E.-P. (1997). “Scaling of structural failure.” Appl. Mech. Rev., 50(10), 593–627.
Behzadi, S., and Jones, F. (2005). “Yielding behavior of model epoxy matrices for fiber reinforced composites: Effect of strain rate and temperature.” J. Macromol. Sci. Phys. Part B, 44(6), 993–1005.
Bernard, E. S. (2006). “Influence of toughness on the apparent cracking load of fiber-reinforced concrete slabs.” J. Struct. Eng., 132(12), 1976–1983.
Boyce, M. C., and Arruda, E. M. (1990). “An experimental and analytical investigation of the large strain compressive and tensile response of glassy polymers.” Polym. Eng. Sci., 30(20), 1288–1298.
Buckley, C. P., and Harding, J. (2001). “Deformation of thermosetting resins at impact rates of strain, Part I: Experimental study.” J. Mech. Phys. Solids, 49(7), 1517–1538.
Chen, W., Lu, F., and Cheng, M. (2002). “Tension and compression tests of two polymers under quasi-static and dynamic loading.” Polym. Test., 21(2), 113–121.
Di Pasquale, G., Motta, O., Recca, A., Carter, J. T., McGrail, P. T., and Acierno, D. (1997). “New high-performance thermoplastic toughened epoxy thermosets.” Polymer, 38(17), 4345–4348.
Dupont, D., and Vandewalle, L. (2004). “Comparison between the round plate test and the RILEM 3-point bending test.” Proc., 6th Int. RILEM Symp. on Fiber Reinforced Concretes, M. di Prisco, R. Felicetti, and G. A. Plizzari, eds., RILEM, Bagneux, France, 101–110.
Fergusson, A. D., Puri, A., Morris, A., and Dear, J. P. (2006). “Flexural testing of composite sandwich structures with digital speckle photogrammetry.” Appl. Mech. Mater., 5(6), 135–144.
Fiedler, B., Hojo, M., Ochiai, S., Schulte, K., and Ando, M. (2001). “Failure behavior of an epoxy matrix under different kinds of static loading.” Compos. Sci. Technol., 61(11), 1615–1624.
Giannotti, M. I., Galante, M. J., Oyanguren, P. A., and Vallo, C. I. (2003). “Role of intrinsic flaws upon flexural behavior of a thermoplastic modified epoxy resin.” Polym. Test., 22(4), 429–437.
Goodier, J. N. (1933). “Concentration of stress around spherical and cylindrical inclusions and flaws.” Trans. ASME, 55(39), 39–44.
G’Sell, C., and Souahi, A. (1997). “Influence of crosslinking on the plastic behavior of amorphous polymers at large strains.” J. Eng. Mater. Technol., 119(3), 223–227.
Hobbiebrunken, T., Fiedler, B., Hojo, M., and Tanaka, M. (2007). “Experimental determination of the true epoxy resin strength using micro-scaled specimens.” Composites, Part A, 38(3), 814–818.
Huang, P., Zheng, S., Huang, J., and Guo, Q. (1997). “Miscibility and mechanical properties of epoxy resins/polysulphone blend.” Polymer, 38(22), 5565–5571.
Jordan, J. L., Foley, J. R., and Siviour, C. R. (2008). “Mechanical properties of Epon 826/DEA epoxy.” Mech. Time-Depend. Mater., 12(3), 249–272.
Khan, M. Z. S., Simpson, G., and Townsend, C. R. (2002). “A comparison of the mechanical properties in compression of two resin systems.” Mater. Lett., 52(3), 173–179.
Lajtai, E. Z. (1972). “Effect of tensile stress gradient on brittle fracture initiation.” Int. J. Rock Mech. Min. Sci., 9(5), 569–578.
Littell, J. D., Ruggeri, C. R., Goldberg, R. K., Roberts, G. D., Arnold, W. A., and Binienda, W. K. (2008). “Measurement of epoxy resin tension, compression, and shear stress-strain curves over a wide range of strain rates using small test specimens.” J. Aerosp. Eng., 21(3), 162–173.
Mackinnon, A. J., Jenkins, S. D., McGrail, P. T., and Pethrick, R. A. (1993). “Dielectric, mechanical and rheological studies of phase separation and cure of a thermoplastic modified epoxy resin: incorporation of reactively terminated polysulphones.” Polymer, 34(15), 3252–3263.
Mannocci, F., Sherriff, M., and Watson, T. F. (2001). “Three-point bending test of fiber posts.” J. Endod., 27(12), 758–761.
Min, B.-G., Hodgkin, J. H., and Stachursky, Z. H. (1993a). “Reaction mechanisms, microstructure and fracture properties of thermoplastic polysulfone-modified epoxy resins.” J. Appl. Polym. Sci., 50(6), 1065–1073.
Min, B.-G., Stachursky, Z. H., and Hodgkin, J. H. (1993b). “Microstructural effects and the toughening of thermoplastic modified epoxy resins.” J. Appl. Polym. Sci., 50(9), 1511–1518.
Odom, E. M., and Adams, D. F. (1992). “Specimen size effect during tensile testing of an unreinforced polymer.” J. Mater. Sci., 27(7), 1767–1771.
Paul, B., and Mirando, L. (1976). “Stresses at the surface of a flat three-dimensional ellipsoidal cavity.” J. Eng. Mater. Technol., 98(2), 164–172.
Vallo, C. I. (2002). “Influence of load type on flexural strength of a bone cement based on PMMA.” Polym. Test., 21(7), 793–800.
Vandewalle, L., Rickstal, F. V., Heirman, G., and Parmentier, B. (2008). “On the round panel and 3-point bending tests.” Proc., 7th Int. RILEM Symp. on Fiber Reinforced Concrete: Design and Applications, RILEM, Bagneux, France, 173–182.
Yekani Fard, M. (2011). “Nonlinear inelastic mechanical behavior of epoxy resin polymeric materials.” Ph.D. thesis, Arizona State Univ., Tempe, AZ.
Yekani Fard, M., Liu, Y., and Chattopadhyay, A. (2011a). “Analytical solution for flexural response of epoxy resin materials.” J. Aerosp. Eng., 25(3), 395–408.
Yekani Fard, M., Liu, Y., and Chattopadhyay, A. (2011b). “Nonlinear flexural behavior and moment curvature response of epoxy resin using digital image correlation technique.” J. Mater. Sci. Eng., 5(2), 212–219.
Yekani Fard, M., Liu, Y., and Chattopadhyay, A. (2012). “Characterization of epoxy resin including strain rate effects using digital image correlation system.” J. Aerosp. Eng., 25(2), 308–319.
Information & Authors
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Published In
Journal of Aerospace Engineering
Volume 27 • Issue 1 • January 2014
Pages: 55 - 63
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Aug 25, 2011
Accepted: Mar 12, 2012
Published online: Mar 14, 2012
Published in print: Jan 1, 2014
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