含氦泡金属铝的动态损伤机制与层裂特性理论研究

Spallation is a widely phenomenon in all kinds of dynamic high-pressure engineering fields, and is a piece of important project in study of shock dynamics of materials. In recent years, remarkable developments have been made about the study of spall strength and damage mechanism for many materials, but there are few reports on the spall properties of irradiation damaged metals. Experimental observations proclaim that there are plenty of He bubbles inside irradiation damaged metals. As yet, knownlegde on the evolution of He bubbles is very limited, which becomes a major factor restricting the development of spall theory of irradiation damaged metals. With the spring up of computing materials science, modelling and simulation based on the crystal structure provide a numerical method for the spall damage study going into microscopic mechanism. In this project, based on the metal Al with He bubbles, we will perform investigation at a variety of levels, including material microscopic mechanism, mecroscopic damage modelling and macroscopic dynamical response. And we are dedicated to reveal the physical mechanism of He bubbles evolution and interaction under dynamic loading, illustrate the dynamics path of He bubbles evolution，explore the damage evolution mechanism and modelling of initial He bubbles, and understanding the macroscopic spall properties of the samples with He bubbles.

层裂现象广泛存在于各种动高压工程领域，是材料冲击动力学研究的一项重要课题。近年来，诸多材料的层裂强度及损伤机制研究已取得长足进展，而关于辐照损伤金属层裂特性研究还鲜有报道。实验观测表明，辐照损伤金属中存在大量纳米尺度氦泡。目前对氦泡损伤演化行为的认识还十分有限，这成为制约辐照损伤金属层裂理论发展的一个主要因素。随着计算材料科学的兴起，基于晶体结构的建模和模拟为层裂损伤研究向微观机理深入提供了数值手段。本项目以含纳米氦泡的金属铝样品为研究对象，开展材料微观演化机理、细观损伤建模和宏观动力学响应等多种物理尺度研究。揭示动载荷下氦泡演化与相互作用过程的物理机制，阐明氦泡演化的动力学途径，探索以氦泡为初始缺陷的损伤演化机制与建模，解读含氦泡样品的宏观层裂损伤特性。

层裂现象广泛存在于各种动高压工程领域，是材料冲击动力学研究的一项重要课题。多年来，关于金属材料层裂强度及损伤机制研究已取得长足进展，而关于辐照损伤金属层裂特性研究至今还很少。众所周知，辐照损伤金属中存在大量纳米尺度氦泡，如何认识这些氦泡的演化行为对于辐照损伤金属层裂理论发展至关重要。随着计算材料科学的兴起，基于晶体结构的建模和模拟为层裂损伤研究向微观机理深入提供了有效数值手段。本项目以含纳米氦泡的金属铝样品为研究对象，在微观演化机理、细观损伤建模和宏观动力学响应等多个物理尺度开展了系列数值模拟和分析研究。基于微观尺度数值模拟，发现了在压缩和拉伸下氦泡局部微结构演化特征，如四面体或八面体的形成，尤其是发现氦泡在卸载过程的压力释放规律和显著膨胀效应。通过进一步模拟研究揭示了初始分布氦泡对金属铝层裂响应的影响机制，获得了以氦泡为主要损伤载体的层裂强度变化特征。基于对氦泡体积与微结构演化的系列研究，发展了金属铝中初始氦泡的尺寸和温度效应的高压氦泡压力体积的描述方法。相应地，通过修正含有氦泡效应的损伤模型，在连续介质尺度实现了对氦泡压力、尺寸等因素宏观效应的计算分析。总体来说，较好地完成了本项目预定研究内容，研究结果丰富了层裂损伤理论研究领域，也集中体现了冲击动力学与材料计算科学的融合。