Mechanical characterization of the nitrocellulose-based visco-hyperelastic binder in polymer bonded explosives

Iqbal, Muhammad Mazhar; Li-Mayer, J.Y.S.; Lewis, D.; Connors, S.; Charalambides, M.N.

doi:10.1063/1.5135093

Cited by 10 publications

(9 citation statements)

References 33 publications

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“…The material, which will be referred to as PBX-1 in this study, is a polymer-bonded explosive composing of 88% volume fraction of HMX crystals and 12% volume fraction of a polymeric binder, specifically a nitrocellulose-based visco-hyperelastic polymer [14]. The binder consists of Nitrocellulose (NC), plasticiser (a mixture of dinitroethylbenzene and trinitroethylbenzene) and stabiliser in the ratio of 1:8:0.02, respectively, with good adhesion properties [14]. The composite has a broad spectrum of HMX crystals sizes to achieve the high volume fraction (88%).…”

Section: Methodsmentioning

confidence: 99%

“…Several studies have shown that the PBX material properties depend on the binder system, volume fraction and crystal size distribution [1,[9][10][11][12][13]. The polymer binder system is often challenging to characterise owing to its highly nonlinear, time-dependent behaviour [10,14]. PBX materials with a higher binder content undergo more substantial strain to failure, while those with smaller crystal sizes for the same volume fraction are stronger [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

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Mechanical Characterisation and Cohesive Law Calibration for a Nitrocellulose Based–Cyclotetramethylene Tetranitramine (HMX) Polymer Bonded Explosive

et al. 2022

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Background Mechanical characterisation of polymer bonded explosives (PBXs) is crucial for their safe handling during storage and transportation. At temperatures higher than the binder's glass transition temperature, fracture is caused predominantly by interface debonding between the binder and explosive crystals. Interfacial friction between debonded crystals can lead to accidental detonation of the PBX material, even under a very small external load. Cohesive zone laws can describe this interfacial debonding. Objective This study aims to experimentally calibrate the interfacial cohesive zone parameters of a nitrocellulose based–cyclotetramethylene tetranitramine (HMX) PBX, a particulate composite with an 88% volume fraction of crystals. Methods Compact tension fracture tests, coupled with Digital Image Correlation (DIC) were used to capture the strain fields around the crack tip. The experimental data were used in conjunction with an extended Mori–Tanaka method considering the effect of interfacial debonding. Results The cohesive zone parameters were successfully calibrated and were found to be crosshead rate independent. The values of the critical traction $${\sigma }_{int}^{max}$$ σ int max and interfacial energy release rate, $${\gamma }_{if}$$ γ if , dropped significantly with increasing temperature. The experimental method followed in this study is generic, and it can be employed to extract the cohesive zone parameters characterising the interface behaviour between the filler and matrix in other particulate filled, polymer composite materials. Conclusions Cohesive zone properties can be experimentally determined to provide inputs in micromechanical simulations linking the microstructure of the PBX composite to its macroscopic response as well as enabling the estimation of hot spot formation at debonded crystal interfaces.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mechanical Characterisation and Cohesive Law Calibration for a Nitrocellulose Based–Cyclotetramethylene Tetranitramine (HMX) Polymer Bonded Explosive

et al. 2022

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“…The combination of viscoelasticity and hyperelasticity is available in commercial finite element software. The development and application of visco-hyperelastic models is topic of a large number of current publications, e.g., [9][10][11][12]. In a preceding work of the author [13], an attempt was made to identify a visco-hyperelastic model using a minimal number of experiments.…”

Section: Combination Of Hyperelasticity and Viscoelasticitymentioning

confidence: 99%

“…Solving the system of (7), (10), and (11), the volume change can be expressed in terms of the bulk modulus and the measurable quantities stretch and nominal stress:…”

Section: Stress Transformation and Compressibilitymentioning

confidence: 99%

Transformation of Test Data for the Specification of a Viscoelastic Marlow Model

Hesebeck

2020

Solids

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The combination of hyperelastic material models with viscoelasticity allows researchers to model the strain-rate-dependent large-strain response of elastomers. Model parameters can be identified using a uniaxial tensile test at a single strain rate and a relaxation test. They enable the prediction of the stress–strain behavior at different strain rates and other loadings like compression or shear. The Marlow model differs from most hyperelastic models by the concept not to use a small number of model parameters but a scalar function to define the mechanical properties. It can be defined conveniently by providing the stress–strain curve of a tensile test without need for parameter optimization. The uniaxial response of the model reproduces this curve exactly. The coupling of the Marlow model and viscoelasticity is an approach to create a strain-rate-dependent hyperelastic model which has good accuracy and is convenient to use. Unfortunately, in this combination, the Marlow model requires to specify the stress–strain curve for the instantaneous material response, while experimental data can be obtained only at finite strain rates. In this paper, a transformation of the finite strain rate data to the instantaneous material response is derived and numerically verified. Its implementation enables us to specify hyperelastic materials considering strain-rate dependence easily.

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“…The behavior of the adhesive is extremely important because it will affect the mechanical response of the polymer composite. The stiffness of the adhesive is five orders of magnitude lower than the stiffness of the explosive crystal [24]. Parker et al [25] find that there is some safety benefit for having binders in HMX, especially when the binder is thermally stable.…”

Section: Introductionmentioning

confidence: 99%

Computational Investigation of Crack-Induced Hot-Spot Generation in Energetic Composites

et al. 2021

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The sensitivity of polymer-bonded explosives (PBXs) can be tuned through adjusting binder material and its volume fraction, crystal composition and morphology. To obtain a better understanding of the correlation between grain-level failure and hot-spot generation in this kind of energetic composites as they undergo mechanical and thermal processes subsequent to impact, a recently developed interfacial cohesive zone model (ICZM) was used to study the dynamic response of polymer-bonded explosives. The ICZM can capture the contributions of deformation and fracture of the binder phase as well as interfacial debonding and subsequent friction on hot-spot generation. In this study, a two-dimensional (2D) finite element (FE) computational model of energetic composite was developed. The proposed computational model has been applied to simulate hot-spot generation in polymer-bonded explosives with different grain volume fraction under dynamic loading. Our simulation showed that the increase of binder phase material volume fraction will decrease the local heat generation, resulting in a lower temperature in the specimen.

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Mechanical characterization of the nitrocellulose-based visco-hyperelastic binder in polymer bonded explosives

Cited by 10 publications

References 33 publications

Mechanical Characterisation and Cohesive Law Calibration for a Nitrocellulose Based–Cyclotetramethylene Tetranitramine (HMX) Polymer Bonded Explosive

Mechanical Characterisation and Cohesive Law Calibration for a Nitrocellulose Based–Cyclotetramethylene Tetranitramine (HMX) Polymer Bonded Explosive

Transformation of Test Data for the Specification of a Viscoelastic Marlow Model

Computational Investigation of Crack-Induced Hot-Spot Generation in Energetic Composites

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