Shear strength measurements in a shock loaded commercial silastomer

Millett, J. C. F.; Whiteman, G.; Stirk, S. M.; Bourne, N. K.

doi:10.1088/0022-3727/44/18/185403

Cited by 14 publications

(9 citation statements)

References 33 publications

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“…The material properties of the Sylgard V R 184 binder were taken as: density q 1 ¼ 1030 kg/m 3 [38], longitudinal wave speed v 1 ¼ 1100 m/s [41], shear wave speed v s1 ¼ 570 m=s [41], longitudinal wave attenuation v 1 ¼ 2.4 dB/MHz/cm [42], thermal conductivity k 1 ¼ 0.27 W/(m-K) [38], and thermal diffusivity c 1 ¼ 1.02 Â 10 -7 m 2 /s [37]. The specific heat capacity is then specified by the relation c p1 ¼ k 1 =ðq 1 c 1 Þ.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Localized Heating Near a Rigid Spherical Inclusion in a Viscoelastic Binder Material Under Compressional Plane Wave Excitation

Mares

Woods

Baker

et al. 2017

Journal of Applied Mechanics

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High-frequency mechanical excitation has been shown to generate heat within composite energetic materials and even induce reactions in single energetic crystals embedded within an elastic binder. To further the understanding of how wave scattering effects attributable to the presence of an energetic crystal can result in concentrated heating near the inclusion, an analytical model is developed. The stress and displacement solutions associated with the scattering of compressional plane waves by a spherical obstacle (Pao and Mow, 1963, “Scattering of Plane Compressional Waves by a Spherical Obstacle,” J. Appl. Phys., 34(3), pp. 493–499) are modified to account for the viscoelastic effects of the lossy media surrounding the inclusion (Gaunaurd and Uberall, 1978, “Theory of Resonant Scattering From Spherical Cavities in Elastic and Viscoelastic Media,” J. Acoust. Soc. Am., 63(6), pp. 1699–1712). The results from this solution are then utilized to estimate the spatial heat generation due to the harmonic straining of the material, and the temperature field of the system is predicted for a given duration of time. It is shown that for certain excitation and sample configurations, the elicited thermal response near the inclusion may approach, or even exceed, the decomposition temperatures of various energetic materials. Although this prediction indicates that viscoelastic heating of the binder may initiate decomposition of the crystal even in the absence of defects such as initial voids or debonding between the crystal and binder, the thermal response resulting from this bulk heating phenomenon may be a precursor to dynamic events associated with such crystal-scale effects.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Localized Heating Near a Rigid Spherical Inclusion in a Viscoelastic Binder Material Under Compressional Plane Wave Excitation

Mares

Woods

Baker

et al. 2017

Journal of Applied Mechanics

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“…The material properties of the Sylgard 184 binder were taken as: density ρ 1 = 1030 kg/m 3 [32], longitudinal wave speed v 1 = 1100 m/s [35], shear wave speed v s 1 = 570 m/s [35], longitudinal wave attenuation χ 1 = 2.4 dB/MHz/cm [36], thermal conductivity k 1 = 0.27 W/(m-K) [32], and thermal diffusivity γ 1 = 1.02 × 10 −7 m 2 /s [31]. The specific heat capacity is then specified by the relation c p 1 = k 1 /(ρ 1 γ 1 ).…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Localized Heating due to Stress Concentrations Induced in a Lossy Elastic Medium via the Scattering of Compressional Waves by a Rigid Spherical Inclusion

Mares

Woods

Baker

et al. 2016

Volume 9: Mechanics of Solids, Structures and Fluids; NDE, Diagnosis, and Prognosis

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High-frequency mechanical excitation has been shown to generate heat within composite energetic materials and even induce reactions in single energetic crystals embedded within an elastic binder. To further the understanding of how wave scattering effects attributable to the presence of an energetic crystal can result in concentrated heating near the inclusion, an analytical model is presented. The stress and displacement solutions associated with the scattering of compressional plane waves by a spherical obstacle (Pao and Mow, 1963) are modified to account for the viscoelastic effects of the lossy media surrounding the inclusion (Gaunaurd and Uberall, 1978). The results from this solution are then utilized to estimate the spatial heat generation due to the harmonic straining of the material, and the temperature field of the system is predicted for a given duration of time. It is shown that for certain excitation and sample configurations, the elicited thermal response near the inclusion may approach, or even exceed, realistic decomposition temperatures of various energetic materials. Although this prediction indicates that viscoelastic heating of the binder may initiate the decomposition of the crystal even in the absence of defects such as initial voids or debonding between the crystal and binder, the thermal response resulting from this bulk heating phenomenon may be a precursor to dynamic events associated with such crystal-scale effects.

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“…The influence of ceramic morphology in terms of comminuted material response was also investigated via a pair of plate-impact experiments [16,17,18], following the approach shown in Fig. 4, with the general aim of studying how the presence of differing target materials / compacts modified an initially planar shock.…”

Section: Plate-impact Experimentsmentioning

confidence: 99%

“…However, unlike the ballistic-based approaches to assessment of comminuted ceramic strength detailed above [7,10,11], this work focused on direct measurement of the strength of shocked ceramic (AD995 alumina). This was achieved by loading ceramic materials into a one-dimensional state of strain (but not stress) via the plate-impact technique [16,17,18]. Embedded longitudinal and lateral stress gauges were employed to determine the variation in stress in both the longitudinal ( x ) and transverse ( y ) directions, allowing calculation of the variation in shear strength () behind the shock via the relation 2 =  x - y .…”

Section: Introductionmentioning

confidence: 99%

“…In this paper ceramic compacts with radically different initial morphologies, acting as comminuted ceramic analogues, were studied. Key experimental approaches, comprising both depth-of-penetration [1,12,13,14] and shock-loading (plate-impact) [16,17,18] studies are introduced before presentation of experimental results. These results were also compared to re-interpreted data from a previous investigation [15].…”

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confidence: 99%

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On the effects of powder morphology on the post-comminution ballistic strength of ceramics

Appleby-Thomas

Wood

Hameed

et al. 2017

International Journal of Impact Engineering

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In this paper in order to try and elucidate the effects of particle morphology on ballistic response of comminuted systems, a series of experiments were carried out via the use of powder compacts with differing initial particle morphologies. This approach provided a route to readily manufacture comminuted armour analogues with significantly different microstructural compositions. In this study pre-formed `fragmented-ceramic' analogues were cold-pressed using plasma-spray alumina powders with two differing initial morphologies (angular and spherical). These compacts were then impacted using 7.62-mm FFV AP (Förenade Fabriksverken Armour Piercing) rounds with the subsequent depth-of-penetration of the impacting projectile into backing Al 6082 blocks used to provide a measure of pressed ceramic ballistic response. When material areal density was accounted for via differing ballistic efficiency calculations a strong indication of particle morphology influence on postimpact ceramic properties was apparent. These results were reinforced by a separate small series of plate-impact experiments, whose results indicated that powder morphology had a strong influence on the nature of compact collapse.which have shown that this comminuted materialon further compactionthen provides a residual resisting strength with respect to penetration [7,8,9]. The concept of ballistic strength discussed in this paper is essentially a measure of the ability of armour to resist penetration following an impact event. A number of different approachesboth experimental and computationalhave been adopted to investigate such material response, with the ultimate aim of allowing improved armour (or munition) development from the resultant insight into armour behaviour. Holmquist et al. [10] undertook a series of experiments to investigate the defeat mechanismsfor SiC tiles impacted in a reverse ballistics configuration by 1-mm diameter Au long rods.By monitoring a variety of impact events via a flash X-ray system the authors were able to discern both the onset of the dwell-penetration transition and the nature of subsequent penetration. Interestingly, a non-linear penetration velocity was discerned in all cases, in line with computational simulations. This behaviour was attributed to the multi-stage nature of the ceramic failurewith impacted material being comminuted before penetration occurred.However, in this study the nature of this comminuted materialand its precise contribution to ballistic resistancewere not discussedsomething which will be investigated here.A recent study by Horsfall et al. [11] however, focused to a greater extent on the contribution of fractured materials. In this study Sintox ® FA tiles comprising 95% alumina were explosively comminuted within a confining steel frame. An in-situ Al 7018-T6 witness plate located directly beneath the tile allowed subsequent depth-of-penetration (DOP) testing [1,12, 13,14] without further disturbance of the comminuted material. Further, as a comparison, 80 m pure alumina powder was pressed in...

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Shear strength measurements in a shock loaded commercial silastomer

Cited by 14 publications

References 33 publications

Localized Heating Near a Rigid Spherical Inclusion in a Viscoelastic Binder Material Under Compressional Plane Wave Excitation

Localized Heating Near a Rigid Spherical Inclusion in a Viscoelastic Binder Material Under Compressional Plane Wave Excitation

Localized Heating due to Stress Concentrations Induced in a Lossy Elastic Medium via the Scattering of Compressional Waves by a Rigid Spherical Inclusion

On the effects of powder morphology on the post-comminution ballistic strength of ceramics

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