材料重复冲击损伤模型与数值计算方法研究

Based on Continuum damage mechanics, the concept of effective stress and the hypothesis of strain equivalence are introduced into Johnson-Cook constitutive model, and a damage model with considering the degradation of mechanical properties of material and its influence on the stress and strain field under repeated impact loading is built. Stress-strain relationship of material with damage is derived according to the damage-coupled J-C model, and is numerically implemented in commercial FEM software ABAQUS by two approaches. A numerical method for the calculation of repeated impact damage is built, and is then applied to compute the accumulative damage of a notched three-point bending specimen under repeated impact loading. Stress, strain and damage at the notch root are investigated. The damage fields of the specimen are studied as well. The variation of the strain near the notch root along with the number of impact coincides with the experimental result of a reference. A repeated impact test of the notched three-point bending specimen is implemented, and the comparison between the computed result with the experimental data validates the feasibility and applicability of the proposed method. Via the comparison with the results obtained by the model without damage coupling, the damage-coupled model can more reasonably reflect the degradation process of mechanical property of materials at the notch tip and the interaction between damage accumulation and impact response.