Continuum Mechanical and Micromechanical Fundamentals of Mechanochemistry of Energetic Materials

含能材料机械化学的连续力学和微机械基础许多研究人员认为剪切应力和剪切带是含能材料和爆炸物中可能的点火源。 提出了一个为期三年的计划，以开发含能材料机械化学的连续力学和微机械基础知识、新的分析和计算方法，并研究和系统化爆炸物剪切应力和应变引发的可能新原因。我们将专注于塑料粘结炸药（例如 PBX-9501），它由通过聚合物粘合剂连接的 HMX 高能晶体组成。本课题的研究目标如下： 1．开发一种系统的多尺度连续介质热力学、动力学和微机械理论，用于含能材料中应力和应变引起的化学反应（CR）和相变（PT），允许CR、剪切应力和大塑性应变、温度和压力之间的热力学和动力学耦合。 将开发非弹性材料CR和PT的新分析和数值方法。2． 分析和数值研究在各种指定应力张量下在微尺度和介观尺度上进行 PT 和 CR 建模的一些典型问题。这些问题包括： a) b 相基体内 d 相的形核和生长； b) 在 HMX 晶体内部或在与粘合剂的边界处以及在现有和塌陷的空隙中升华和 CR 期间气相的成核； c) 多级 PT 和 CR.3。解析和数值研究微观、细观和宏观尺度剪切带中的反应诱发塑性和相变诱发塑性现象，及其对CR和PT的热力学和动力学（作为正机械化学反馈）以及对含能材料的力学行为（作为新的变形机制）的影响。 4．对炸药中组合剪切压力点火和初始后点火过程进行多尺度有限元建模和实验描述。 将找到导致炸药剪切敏感性的材料参数和负载条件。

Continuum Mechanical and Micromechanical Fundamentals ofMechanochemistry of Energetic MaterialsShear stress and shear banding are suggested by many investigators as possible sources of ignition in energetic materials and explosives. A three-year program is proposed to develop continuum mechanical and micromechanical fundamentals of mechanochemistry of energetic materials, new analytical and computational methods, and to investigate and systematize possible new reasons for shear stress and strain initiation of explosives. We will concentrate on plastic bonded explosives (e.g. PBX-9501) which consist of HMX energetic crystals connected by a polymer binder. The objectives of the research proposed are as follows:1. To develop a systematic multiscale continuum thermodynamic, kinetic and micromechanical theory for stress- and strain-induced chemical reactions (CR) and phase transformations (PT) in energetic materials allowing for thermodynamic and kineticcoupling between CR, shear stress and large plastic strains, temperature and pressure. New analytical and numerical methods for CR and PT in inelastic materials will be developed.2. To study analytically and numerically some typical problems for modeling of PTand CR at the microscale and mesoscale under various prescribed stress tensors. These problems include: a) Nucleation and growth of the d phase inside of the b phase matrix; b) Nucleation of the gas phase during sublimation and CR inside the HMX crystal or at the boundary with the binder, as well as in existing and collapsing voids; c) Multistage PT and CR.3. To investigate analytically and numerically reaction-induced plasticity and transformation-induced plasticity phenomena in the shear band at micro-, meso-, and macroscales, and their effect on the thermodynamics and kinetics of CR and PT (as positivemechanochemical feedback), as well as on the mechanical behavior of energetic materials (as the new deformation mechanism).4. To conduct multiscale finite element modeling and description of experiments on combined shear-pressure ignition and initial post-ignition processes in explosives. Material parameters and loading conditions responsible for shear sensitivity of explosives will be found.