Continuum Mechanical and Micromechanical Fundamentals of Mechanochemistry of Energetic Materials

含能材料力学化学的连续介质力学和细观力学基础剪切应力和剪切带被许多研究人员认为是含能材料和炸药的可能起火源。提出了一项为期三年的计划，旨在发展含能材料机械力化学的连续介质力学和细观力学基础、新的分析和计算方法，并调查和系统化炸药产生剪应力和应变的可能新原因。我们将集中讨论塑料粘结炸药(例如PBX-9501)，它由HMX高能晶体通过聚合物粘结剂连接而成。1.建立含能材料应力应变化学反应(CR)和相变(PT)的系统多尺度连续热力学、动力学和细观力学理论，考虑CR、剪应力和大塑性应变、温度和压力之间的热力学和动力学耦合。将发展非弹性材料中CR和PT的新的解析和数值方法。在不同的应力张量下，从微观和细观两个尺度对PTR和CR模型的一些典型问题进行了解析和数值研究。这些问题包括：a)b相中d相的形核和长大；b)在HMX晶体内部或与粘结剂的边界以及在现有和坍塌的空隙中升华和CR过程中气相的形核；c)多阶段PT和Cr3。分析和数值研究剪切带微观、细观和宏观尺度上的反应诱导塑性和相变诱导塑性现象及其对CR和PT热力学和动力学的影响(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。进行多尺度有限元模拟和描述炸药中剪切压力联合点火和点火后初始过程的实验。找出了影响炸药剪切敏感性的材料参数和加载条件。

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.