failure strength of Dyneema does not depend on the gage length of the fiber since no change in strength was observed at shorter gage lengths. Future work should include shorter gage lengths to further probe this observation. The results of this study show higher failure strengths compared to the study by Hudspeth et al. [5] on Dyneema SK76, but compare well with published data by Dyneema [14] and a study by Russell et al. on SK76 fibers and yarns [3]. In general, the stress–strain behavior of the Dyneema fiber is increasingly linear with increasing strain rate [3, 15, 16]. The average behavior of 5 mm gage length samples is shown in Fig. 1.2. Error bars represent one standard of deviation of strength at each strain value. At low rates, the primary deformation mode of the Dyneema UHMWPE fiber is creep [3, 17–19]. Creep was also noted on non-ballistic grades of Dyneema such as SK66 [20] and SK65 [21]. In each case the creep component increases with decreasing strain rate. The increase in linearity of the stress–strain curve is also seen when experiments at different temperatures are conducted [20] suggesting that the mechanism of failure at low temperatures is similar the mechanism of failure at high strain rates. References 1. Lin SP, Han JL, Yeh JT, Chang FC, Hsieh KH (2007) Surface modification and physical properties of various UHMWPE fiber reinforced modified epoxy composites. J Appl Polym Sci 104:655–665 2. Umberger PD (2010) Characterization and response of thermoplastic composites and constituents. Master’s thesis 3. Russell BP, Karthikeyan K, Deshpande VS, Fleck NA (2013) The high strain rate response of ultra high molecular weight polyethylene: from fibre to laminate. Int J Impact Eng 60:1–9 4. Cochron S, Galvez F, Pintor A, Cendon D, Rosello C, Sanchez-Galvez V (2002) Characterization of fraglight non-woven felt and simulation of FSP’s impact in it. R&D 8927-AN-01 5. Hudspeth M, Nie X, Chen W (2012) Dynamic failure of Dyneema SK76 single fibers under biaxial shear/tension. Polymer 53:5568–5574 6. Lim J, Zheng JQ, Masters K, Chen WW (2010) Mechanical behavior of A265 single fibers. J Mater Sci 45:652–661 7. Lim J, Chen WW, Zheng JQ (2010) Dynamic small strain measurements of Kevlar ® 129 single fibers with a miniaturized tension Kolsky bar. Polym Test 29:701–705 8. Lim J, Zheng JQ, Masters K, Chen WW (2011) Effects of gage length loading rates, and damage on the strength of PPTA fibers. Int J Impact Eng 38:219–227 9. Cheng M, Chen W, Weerasooriya T (2005) Mechanical properties of Kevlar KM2 Single fiber. J Eng Mater Technol 127:197–203 10. Sanborn B, Weerasooriya T (2013) Quantifying damage at multiple loading rates to Kevlar KM2 fibers due to weaving and finishing. ARL-TR-6465. June 2013 11. Kim JH, Heckert AN, Leigh SD, Rhorer RL, Kobayashi H, McDonough WG, Rice KD, Holmes GA (2014) Statistical analysis of PPTA fiber strengths measured under high strain rate condition. Compos Sci Technol 98:93–99 12. Kim JH, Heckert NA, McDonough WG, Rice KD, Holmes GA (2013) Single fiber tensile properties measured by the Kolsky bar using a direct fiber clamping method. In: Proceedings of society for experimental mechanics conference. Lombard, IL 13. Kim JH, Heckert NA, Leigh SD, Kobayashi H, McDonough WG, Rice KD, Holmes GA (2013) Effects of fiber gripping methods on the single fiber tensile test: I. Non-parametric statistical analysis. J Mater Sci 48:3623–3673 Fig. 1.2 Stress–strain response at multiple strain rates. Note the increase in linearity for the same gage length with increasing strain rate. The curves in these plots represent the average behavior of ten experiments 1 Tensile Properties of Dyneema SK76 Single Fibers at Multiple Loading Rates Using a Direct Gripping Method 3
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