Mechanical properties of silicone based composites as a temperature insensitive ballistic backing material for quantifying back face deformation

Edwards, Tara D.; Bain, Erich D.; Cole, Shawn T.; Freeney, Reygan M.; Halls, Virginia; Ivancik, Juliana; Lenhart, Joseph L.; Napadensky, Eugene; Yu, Jian; Zheng, James; Mrozek, Randy A.

doi:10.1016/j.forsciint.2018.01.014

Cited by 13 publications

(16 citation statements)

References 35 publications

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“…This paper reports valuable material data on the new backing materials developed by the U.S. Army, which is important to ballistic researchers and the standards-based body armor testing community. This work supplements prior quasi-static indentation and ballistic resistance studies [15] for a complete characterization on SCBM properties and RP1 under shear deformation at low strain rates. Additionally, this work highlights the effectiveness of rheological techniques to help optimize formulations, to set quality control guidelines for RP1 and any candidate replacement material, as well as to establish documentary performance standards and specifications related to next-generation BWMs for body armor testing.…”

Section: Introductionmentioning

confidence: 57%

“…RP1 clay was used as received from the manufacturer (Sculpture House, Springhill, NJ, USA). The SCBMs were produced by the ARL (Aberdeen Proving Ground, MD, USA) [14,15]. Three formulations of SCBM containing mass fractions of fumed silica that ranged from 13% to 18% by mass and were designated as SCBM #1, SCBM #2, and SCBM #3 were investigated.…”

Section: Methodsmentioning

confidence: 99%

“…Three formulations of SCBM containing mass fractions of fumed silica that ranged from 13% to 18% by mass and were designated as SCBM #1, SCBM #2, and SCBM #3 were investigated. The material preparation procedure and processing parameters have been described in detail in Edwards et al [15]; here, we briefly describe the SCBM preparation method for the sake of completeness. Untreated fumed silica, PDMS (with a low glass transition temperature near −120 °C), and corn starch were weighed out and pre-mixed using a commercial countertop stand mixer until the material became homogeneous by visual inspection.…”

Section: Methodsmentioning

confidence: 99%

“…The Army Research Laboratory (ARL) has developed a room-temperature silicone composite backing material (SCBM) as a candidate material to replace RP1 [14,15]. The family of SCBMs is a particle-loaded polymer-based composite that consists of three components, i.e., non-crosslinked linear polydimethylsiloxane (PDMS), fumed silica, and corn starch [15]. The PDMS has a molecular weight that is slightly more than the entanglement molecular weight, such that elastic recovery is minimized.…”

Section: Introductionmentioning

confidence: 99%

“…This three-component system is anticipated to meet most criteria for BWM, including the minimal number of components and readily tunable formulation, controllable mechanical properties, nontoxicity, low adhesion to the armor, minimal odor, low cost, minimal temperature sensitivity, and reusability at room temperature [14]. Edwards et al have shown that the SCBM exhibits similar room temperature properties compared to heated RP1 by conducting side-by-side tests including quasi-static indentation and compression tests, drop tests, and body armor ballistic resistance tests [15]. While these previous studies provide correlation between the quasi-static and dynamic performance of SCBM and RP1, it is difficult to classify the deformation behavior of SCBM and RP1 as a function of strain, strain rate, and temperature.…”

Section: Introductionmentioning

confidence: 99%

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Rheological Characterization of Next-Generation Ballistic Witness Materials for Body Armor Testing

et al. 2019

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Roma Plastilina No. 1 (RP1), an artist modeling clay that has been used as a ballistic clay, is essential for evaluation and certification in standards-based ballistic resistance testing of body armor. It serves as a ballistic witness material (BWM) behind the armor, where the magnitude of the plastic deformation in the clay after a ballistic impact is the figure of merit (known as “backface signature”). RP1 is known to exhibit complex thermomechanical behavior that requires temperature conditioning and frequent performance-based evaluations to verify that its deformation response satisfies requirements. A less complex BWM formulation that allows for room-temperature storage and use as well as a more consistent thermomechanical behavior than RP1 is desired, but a validation based only on ballistic performance would be extensive and expensive to accommodate the different ballistic threats. A framework of lab-scale metrologies for measuring the effects of strain, strain rate, and temperature dependence on mechanical properties are needed to guide BWM development. The current work deals with rheological characterization of a candidate BWM, i.e., silicone composite backing material (SCBM), to understand the fundamental structure–property relationships in comparison to those of RP1. Small-amplitude oscillatory shear frequency sweep experiments were performed at temperatures that ranged from 20 °C to 50 °C to map elastic and damping contributions in the linear elastic regime. Large amplitude oscillatory shear (LAOS) experiments were conducted in the non-linear region and the material response was analyzed in the form of Lissajous curve representations with the values of perfect plastic dissipation ratio reported to identify the degree of plasticity. The results show that the SCBM exhibits dynamic properties that are similar in magnitude to those of temperature-conditioned RP1, but with minimal temperature sensitivity and weaker frequency dependence than RP1. Both SCBM and RP1 are identified as elastoviscoplastic materials, which is particularly important for accurate determination of backface signature in body armor evaluation. The mechanical properties of SCBM show some degree of aging and work history effects. The results from this work demonstrate that the rheological properties of SCBM, at small and large strains, are similar to RP1 with substantial improvements in BWM performance requirements in terms of temperature sensitivity and thixotropy.

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Section: Introductionmentioning

confidence: 57%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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