Abstract
A microstructure finite element method combining the cohesive zone model (CZM) is used to simulate the mechanical behavior, deformation, and failure of polymer-bonded explosive (PBX) 9501 under quasi-static loading. PBX 9501 consists of Cyclotetramethylene tetranitramine (HMX) filler particles with a random distribution packaged in a polymeric binder. The particle is treated as elastic and the binder as viscoelastic. Cohesive elements with a bilinear softening law are inserted into the particle/binder interface, the HMX particle, and the binder to study the interface’s debonding and failure evolution. Macroscopic stress–strain curves homogenized across the microstructure under tension and compression with different strain rates are basically consistent with the experimental data. The interface debonding approximately vertical to the loading direction is the primary failure mechanism under tension, while shear failure along the interfaces and particle fracture plays a significant role under compression. The effects of interface strengths and strain rates on the performance of PBX 9501 are also evaluated. The tensile and compressive strengths are dependent on the interface strength and strain rate, but the failure paths are insensitive. This model is shown to accurately predict macroscopic responses and improve our understanding of the relationship between the mechanical behavior and microstructure of PBX 9501.
Highlights
Polymer-bonded explosives (PBXs) are a type of highly filled particulate composite, generally composed of high-energy single-compound explosive particles and a polymeric binder [1,2]
Three interface cohesive strengths of 1, 1.66, and 3 MPa are used for the model illustrated in Figure 10b to investigate the mechanical behavior of PBX 9501 under uniaxial tension
We have presented a method that embeds cohesive elements throughout a microstructure model obtained by Voronoi tessellation, to study the response of PBX 9501 subjected to quasi-static loading
Summary
Polymer-bonded explosives (PBXs) are a type of highly filled particulate composite, generally composed of high-energy single-compound explosive particles and a polymeric binder [1,2]. A set of finite element models, including 2D polygons of actual SEM images, idealized 2D circles, and 3D spheres of particles, were used in the analysis The results from these studies show that the mechanical properties are highly sensitive to cohesive law parameters but are insensitive to the model size. A bilinear cohesive law with normal (mode I) and tangential direction (mode II) is developed, and cohesive elements are inserted into the microstructure along the element boundaries of the particle, binder, and particle/binder interface to study the interface’s debonding, failure evolution, and shear fracture Both tension and compression simulations are carried out for the different mechanical responses and failure mechanisms under different stress states. The objective is to greatly improve the understanding of debonding, damage, and failure mechanisms under quasi-static loading at the micro level
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