描述蠕变过程中内耗的四参量模型

FOUR-PARAMETER MODEL FOR DESCRIBING THE BEHAVIOUR OF INTERNAL FRICTION MEASU-RED DURING CREEP TESTS

实验表明:蠕变过程中的内耗兼有Maxwell二参量模型的性质和滞弹性三参量模型的性质。 本文提出一个用以描述蠕变过程中内耗的四参量模型。由此模型推导出的内耗表达式为 Q^(-1)=1/(ωτ_1)+△(ωτ_2)/(1+ω~2τ_2~2),式中ω为测量圆频率,τ_1和τ_2分别为粘弹性内耗和滞弹性内耗的弛豫时间,△为弛豫强度。 这个内耗表达式可以满意地说明蠕变过程中内耗随时间的变化,以及内耗对蠕变速率、实验温度和测量频率的依赖关系。 文中还从微观上分析了四参量模型中各元件的物理本质。

Experiments show that the internal friction measured at low frequency during creep tests exhibits both the behaviours of Maxwell two-parameter model and standard anelastic three-parameter model. In this paper, a four-parameter model is proposed for describing the behaviour of such internal friction. Based on this model, the expression of internal friction is derived to be Q^(-1)=1/ωt_1+△ωτ_2/(1+τ~2t_2~2) where ω is the circular frequency of vibration, τ_1 and τS_2 are respectively the relaxation times for viscoelastic and anelastic relaxation, and A the relaxation strength. This expression can satisfactorily explain the change of internal friction with creep time, and the dependence of internal friction on the creep rate, test temperature and the measuring frequency. The physical origin of each element in the four-parameter model is analyzed in the light of the micro-structure.