The behavior of an epoxy resin under one-dimensional shock loading

Abstract

The response of an epoxy resin has been investigated using the methods of plate impact to generate planar shock waves. In particular, the Hugoniot, both in stress–particle velocity and shock velocity–particle velocity space, and the variation of shear strength with impact stress, have been investigated. Comparison of the results of this investigation with those of previous workers shows good agreement. Measurements of lateral stress, which have been used to determine the shear strength have indicated that shear strength increases with longitudinal stress in the range investigated. Further, lateral stresses have been shown to decrease behind the shock front, implying an increase of strength of this material during shock loading. It would seem possible that this is a manifestation of the viscoplastic nature of epoxy based resins.

The effect of orientation on the shock response of a carbon fibre–epoxy composite

“…This type of behaviour is typical of a wide range of materials, including metals [10] and some polymers [11], including epoxy resins [12,13]. A linear U s -u p relationship was also observed by Zhuk et al [4], thus it would appear that in the through thickness orientation, this class of composite displays fairly typical behaviour.…”

On the Shock Response of Polymers to Extreme Loading

“…thermosets) are amorphous and show no order; polycarbonate (PC) and epoxy discussed here are in this class. The epoxy tested in [29] was cured from a mixture of an epoxy resin mixture, a flexibilizer, and a hardener. The resin mixture consisted of 14-22 % 1,4-butanedioldiglycidyl ether (C 10 H 18 O 4 ) and 78-86 % of the product of reaction between epichlorohydrin (C 3 H 5-ClO) and bisphenol to give an approximate empirical formula of C 21 H 24 O 4 [29].…”

“…The epoxy tested in [29] was cured from a mixture of an epoxy resin mixture, a flexibilizer, and a hardener. The resin mixture consisted of 14-22 % 1,4-butanedioldiglycidyl ether (C 10 H 18 O 4 ) and 78-86 % of the product of reaction between epichlorohydrin (C 3 H 5-ClO) and bisphenol to give an approximate empirical formula of C 21 H 24 O 4 [29]. The thermoplastic PTFE is semicrystalline and consist of spherulites embedded within an amorphous matrix [30,31].…”

“…4 Response of the thermoset epoxy. Two stress levels 3.5 (solid) and 2 GPa dashed) showing evolution of the shear stress behind the shock [29] the experiments represent different loading geometries; in one case, an asymmetric impact with a metal flyer plate and in the second, a symmetric impact where the impactor and target were both polycarbonate. The two stress histories show differing response over the first microsecond but lie one upon the other thereafter; there is a perturbation in the case of the metal flyer over the first microsecond after which the shear stress behind the front relaxes to that seen in the symmetrical case.…”

“…Figure 4 shows the development of the stress field within the thermoset epoxy compressed by impact in the low-pressure regime. Sensors were embedded in the flow, a distance from the impact face to observe the development of the stress field behind the shock [29]. In each case the difference between the two components of stress determines twice the shear stress and these strength histories are represented by solid lines in the figure.…”