基体微尺度效应对弹塑性多孔洞材料本构势及孔洞长大的影响

THE INFLUENCES OF MICROSCOPE SIZE EFFECT OF MATRIX ON PLASTIC POTENTIAL AND VOID GROWTH OF POROUS MATERIALS

基于尺度相关的应变梯度塑性SG理论,对含孔洞的球形体胞模型进行了解析分析,得到了在基体梯度塑性环境下球形孔洞的演化规律,给出了弹塑性孔洞材料的宏观屈服面方程。与现有的基于尺度无关塑性理论的Gurson模型相比,该模型考虑了基体材料的特征长度l与孔洞半径α之比λ(λ=l/α)对多孔材料宏观屈服面和孔洞演化规律的影响。当不计基体材料的塑性梯度效应和硬化效应时,该模型能退化到经典的Gurson模型。

Based on approximate theoretical analyses on a representative spherical cell containing a spherical microvoid, the influences of matrix materials' microscopic size on the macroscopic constitu- tive potential theory of porous material and microvoid growth have been investigated in detail. By as- suming that the plastic deformation behavior of matrix materials follows the strain gradient (SG) plastic theory proposed by Fleck and Hutchinson (1997), the ratio (λ=l/α) of the intrinsic characteristic length l of marix matrials to the microvoid radius α is introduced into the plastic constitutive potential and the void growth law. The present results indicate that, when the radius α of microvoids is compa- rable with the intrinsic characteristic length l of the matrix materials, the influence of microscopic size effect on both the constitutive potential and the microvoid evolution predicted cannot be ignored. And when the void radius α is much lager than the intrinsic characteristic length l of matrix materials, the present model can retrogress automatically to the improved Gurson model considering the strain harden- ing effect of matrix materials.