摘要
脆性材料,如岩石,其动力强度随应变率的变化特性以往大多局限于实验研究,而理论研究,特别是从低应变率区到高应变率区的系统的物理机制研究很少。基于现有的研究资料,对不同应变率区的材料强度的应变率依赖性机理及其转换进行了探讨。分析表明,在小应变率的范围内,材料强度-应变率依赖性受热活化机制控制;随着应变率进一步增加,材料的宏观粘性阻尼机制(声子阻尼)出现,并逐渐占据主导地位,材料的惯性影响逐渐明显;在高应变率区时,材料惯性的影响非常大,这时不同尺寸的缺陷的增长将同时启动,在材料没有缺陷的地方热活化机制引起原子键的断裂。这样可以把材料强度-应变率依赖性看作是热活化机制与宏观粘性机制并行存在、相互竞争的结果。这两种机制在不同的应变率区占据主导地位。基于上述结论,给出了联合的热活化与粘性机制相互竞争的材料强度-应变率依赖模型,并对该模型的有效性对照实验资料进行了检验,结果表明,与实验符合得很好。
Based on available research results, the physical mechanism of strength-strain rate sensitivity in different strain rate regions and the transition between them are studied. The study result shows that in small strain rate region, strength-strain rate sensitivity is controlled by thermoactivational mechanism. With the increase of strain rate, the macro-viscosity mechanism arises, and gradually becomes dominant. In high strain rate region, inertia effect becomes very significant, and the growth of defects of a wide range of sizes will be initiated simultaneously, and then the thermoactivational rupture of atomic bonds will take place in the area without defects. Thus the strength-strain rate sensitivity can be considered as the result of competition between the coexisting thermoactivation mechanism and the macro-viscosity mechanism, which plays dominant roles in different strain rate regions. On this basis, a unified model of competition between thermoactivational mechanism and the macro-viscosity mechanism is given, and the effectiveness of the model is verified with experiment data and good accordance is obtained with the experiment data.
出处
《岩石力学与工程学报》
EI
CAS
CSCD
北大核心
2003年第2期177-181,共5页
Chinese Journal of Rock Mechanics and Engineering
基金
国家自然科学基金资助项目(50179038)
教育部回国留学人员启动基金项目(教外司留[1999]747号)
