圆柱形陶瓷结构中含偏斜模式的应力波与陶瓷冲击破坏研究

Impacting failure mechanism of ceramics is a crucial scientific problem for penetration and protection of ceramic armor. Temporal-spatial evolution of the stress waves in ceramic structure is fundamental to determine the stress state and reveal ceramic failure mechanism. This project will focus on three-dimensional ceramics cylinder and thin circular plate as well as cylindrical shell structure and study the stress wave and ceramic impact failure problems. Based on the modified stress wave theory containing deviatoric mode in Cartesian coordinates, the equations of stress waves containing deviatoric mode will be built up under cylindrical coordinates. The interface effects including incidence, reflection and transmission of the stress waves on the cylindrical interfaces will be proposed. Temporal-spatial evolution of the stress waves in compressive bar and plate impact experiments will be verified by experiments. The forms of impact failure in three-dimensional cylindrical ceramic structures will be investigated by the compressive bar and the plate impact experiments under intensive dynamic loading. Combined with the analysis of the stress waves, the relevance of the ceramic impact failure with the stress state in wave motion will be examined. The strength and failure criterion of ceramics will be investigated. The constitutive relation for ceramic dynamic failure will be developed. The dynamical equations for ceramic impact failure will be developed. The parameters related with the strength and failure of ceramics will be determined. The wave motion and failure process will be predicted and demonstrated by numerical analysis and experiments. In the final, the optimized design for impact protection of ceramics structures will be explored.

陶瓷冲击破坏机制是陶瓷穿甲侵彻与冲击防护领域的关键科学问题，研究陶瓷结构中应力波的时空演化是确定应力状态和揭示陶瓷冲击破坏的前提。本项目着眼于三维圆柱和薄圆板以及柱壳陶瓷结构，研究应力波的时空演化和陶瓷冲击破坏动力学问题。基于直角坐标系下含偏斜模式的修正应力波理论，建立柱坐标系下含偏斜模式应力波的波动方程，建立柱面上应力波的激发、入射、反射和透射的界面效应模型。实验验证在压杆和平板冲击下应力波的时空演化。开展强动载下陶瓷压杆和平板冲击实验，考察三维圆柱形陶瓷结构的冲击破坏形式。结合应力波的分析，建立陶瓷冲击破坏与波动应力状态的时空演化的关联性。考察并发展陶瓷动态强度的表征和破坏判据，发展陶瓷动态破坏本构关系，建立陶瓷冲击破坏的动力学方程，提出陶瓷强度性能参数和动态破坏性能参数。预测和验证三维柱形陶瓷结构中的波动和破坏过程，提出陶瓷结构冲击防护优化设计。

陶瓷冲击破坏机制是陶瓷穿甲侵彻和冲击防护领域的重要研究课题，应力波的时空演化是揭示陶瓷复杂破坏模式的基础和前提。以平板冲击和分离式霍普金森压杆为主要手段来研究陶瓷动态性能及破坏测试时，试件为薄圆柱片或短圆柱形。本项目针对圆柱形陶瓷试件，以创立新的应力波理论为出发点，以统一的视角研究平板和柱形陶瓷结构中的波动过程，以建立动态应力与陶瓷动态破坏模式的内在联系。.项目的主要内容：.（1）研究广义弹性力学。基于广义弹性力学，研究弹性应力波理论。.（2）研究平板冲击下弹性应力波的波动方程和传播特性以及陶瓷冲击试验验证。.（3）研究柱坐标系和球坐标系下弹性应力波的传播结构，内外爆冲击下厚壁柱壳和厚壁球壳应力波的传播。.（4）研究应力波形成的应力状态与陶瓷动态破坏模式的关系。.重要结果和科学意义：.（1）创立了弱耦合的弹性应力波理论，弹性应力波是体积波和形变波构成的弱耦合波系。.（2）创立了平板冲击下的双脉冲应力波结构。第一个脉冲是以体应变和偏应变表征的复合脉冲，第二个脉冲只有偏应变的传播。平板冲击为三维应变状态，存在体积波和形变波的传播。.（3）平板冲击下自由面速度曲线的二次压缩信号代表形变波，理论上解决了弱冲击下陶瓷等脆性材料的二次压缩信号问题。双波结构以及动态应力的时空演化，为解析破坏波和层裂以及加载面的冲击压缩损伤提供了理论基础。.（4）利用柱和球坐标系下的应力波理论，创立了体积波和形变波的双脉冲应力波结构。内爆冲击下厚壁柱壳和球壳的螺旋剪切破坏是应力波形成的动态应力状态的结果。.（5）建立了轴向冲击下圆柱结构中应力波的传播结构，为改进杆板冲击试验技术提供了基础理论指导。