绝热剪切带内微孔洞演化规律研究

为深入了解绝热剪切带内微孔洞的演化规律,进而揭示高应变率加载条件下绝热剪切破坏的特殊规律,本文对D35钢进行了约束爆破实验,爆破后回收圆筒的微观观察表明,绝热剪切破坏要经过绝热剪切带内微孔洞形核、长大和相互联接形成裂纹等一系列演化过程.在Guduru P等人的测试结果和Li Shaofan等人数值仿真结果基础上,通过简化(剪切带内的温度分布为由剪切带中心向边缘线性降低,并最终降至与基体温度相同; 微孔洞的形核、长大受温度控制,长大速度随温度呈指数规律降低)对Timothy S P和Hutchings I M的模型进行了修正,修正后的模型可以定量的描述绝热剪切带内微孔洞的演化直至破坏的全过程,模型的描述与微观分析获得的实验结果有较好的一致性.

MICRO-VOID EVOLUTION IN THE ADIABATIC SHEAR BANDS

In order to understand the law of evolution of micro-voids in the adiabatic shear band, and open out the special failure rule when materials under high strain rate are loading, restricted detonation experiment was adopted to study steel D35. Tubes loaded by high explosive were observed by scanning electron microscope (SEM). Micro-voids nucleation, growth, and coalescence to damage in adiabatic shear bands (ASB) were observed by SEM. Based on the experimental results from Guduru's tests to ASB temperature field and Li Shaofan's simulation, the predigestion were applied to modify Timothy and Nutchings' model, viz. that (1)the temperature in ASB center is the highest, and fall linearly to be the same as the other places, (2) micro-voids' nucleation and growth in the ASB are controlled by temperature, and the growth velocity is exponential. The modified model can interpret the micro-void's nucleation, growth, and coalescence quantitatively.