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A Pressure-Dependent Plasticity Model for Polymer Bonded Explosives under Confined Conditions

Wei Qiang, Huang Xi-cheng, Chen Peng-wan, Liu Rui

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 3

339--368

EN

The safety of explosives is closely related to the stress state of the explosives. Under some stress stimulation, explosives may detonate abnormally. It is of great significance to accurately describe the mechanical response of explosives for the safety evaluation of explosives. The mechanical properties of polymer bonded explosives (PBXs) strongly depend on pressure. In this study, the mechanical behaviour of PBXs under confined conditions was investigated. It was found that the stress-plastic strain response of a PBX under high confining pressures is a combination of the non-linear and linear hardening portions. However, the linear hardening portion has often been neglected in characterizing the mechanical behaviour of a PBX under such pressures. The Karagozian and Case (K&C) model was applied to characterize the mechanical behaviour of PBXs. The numerical results demonstrated that when the confining pressure was high, the K&C model could not adequately match the experimental data due to the limitation of the damage model. Therefore, a new damage model was developed by means of considering intragranular damage and transgranular damage. This modification made it possible to introduce a linear hardening process into the original K&C model. The method proposed to describe the stress-strain results under high confining pressures was to consider the stress-plastic strain curve, including the nonlinear and linear hardening portions. The damage evolution of the original K&C model and a linear hardening model were applied for the nonlinear and linear hardening portions respectively. The influence of the linear hardening model on the damage evolution of the original K&C model was included when describing the nonlinear hardening portion. A comparison between simulation and experiment showed that the modified K&C model could well describe the mechanical response of PBXs under different confining pressures.

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Enhanced Non-linear Viscoelastic Properties of Polymer Bonded Explosives Based on Graphene and a Neutral Polymeric Bonding Agent

Lin C., He G., Liu J., Pan L., Liu S.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 4

788--805

EN

During their long-term storage and transport, polymer bonded explosives (PBXs) will be subjected to complex thermal physical environments with combined thermal and mechanical loads. The creep behaviour results in a change of physical and mechanical properties, which consequently influences the explosive performance. In this work, graphene and a neutral polymeric bonding agent (NPBA) were selected to improve the non-linear creep properties of 1,3,5-triamino-2,4,6-trinitrobenzene (TATB)-based PBXs. The results were compared with the creep response of the corresponding PBXs without additives and with graphene alone. It was observed that graphene and an NPBA exhibited a positive effect, improving the creep resistance of TATB-based PBXs. The compressive and tensile strength of 0.5 wt.% graphene-filled PBXs were improved by 5.1% and 29.2%, respectively, compared to raw TATB-based PBXs without additives. The performance of the PBXs was further enhanced by the addition of 0.1 wt.% NPBA. For a given stress and temperature, the TATB-based PBXs with graphene and NPBA deformed significantly less than the PBXs filled with graphene alone.

3

Otrzymywanie i badania kompozycji wybuchowych zawierających żywicę poliestrową

Nita M., Warchoł R., Prasuła P.

Problemy Techniki Uzbrojenia

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2014

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R. 43, z. 130

45--57

PL

W wyniku pracy otrzymano, jak również wstępnie scharakteryzowano, cztery kompozycje wybuchowe, które mogą zostać użyte w procesie elaboracji elementów środków bojowych metodą zalewania. Podstawowymi kruszącymi materiałami wybuchowymi (KMW) stosowanymi w postaci drobnokrystalicznej w badanych kompozycjach były: heksogen (RDX) oktogen (HMX), pentryt (PETN), zaś substancją wielkocząsteczkową - żywica poliestrowa, która nadawała lejność kompozycji przed jej sieciowaniem. Zbadano proces topnienia i rozkładu termicznego czystych KMW oraz kompozycji wybuchowych przygotowanych na ich bazie za pomocą analizy termicznej obejmującej różnicową kalorymetrię skaningową (DSC) i analizę termograwimetryczną (TGA) w opcji TG i DTG, a także określono kształt i wielkości kryształów KMW za pomocą mikroskopu optycznego. W pracy przedstawiono również wyniki pomiarów wrażliwości wytypowanych kompozycji na uderzenie, tarcie i działanie strumienia kumulacyjnego. Ponadto określono prędkości i ciśnienia detonacji oraz średnice krytyczne wybranych ładunków bazujących na krystalicznych materiałach wybuchowych i żywicy poliestrowej.

EN

In the frame of works described in this paper, there were obtained and preliminary characterized explosive compositions able to be inserted into munitions by casting. Crystalline high explosives (HEs) used in the tested compositions were hexogene (RDX), octogene (HMX) and penthrite (PETN), and as the binder the polyester resin was used. This resin in its prepolimer form, gave castability of the tested compositions prior their crosslinking. There were investigated melting and thermal decomposition of both pure HEs and prepared compositions by means of thermal analysis techniques including differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) operating in TG and TGA modes. There were also determined shapes and sizes of HEs crystals in optical microscope. Test results on sensitivity of selected compositions to mechanical impact, friction and to action of shaped charge jet (SCJ) were presented as well. Due to detonation tests there were determined velocity of detonation (VD), pressure detonation (PD) and critical diameters of explosive charges based on HEs and polyester resin.