Theoretical analysis and finite element （FE） simulation have been carried out for a constant specific load rate （CSLR） indentation creep test. Analytical results indicate that both the representative stress and th...Theoretical analysis and finite element （FE） simulation have been carried out for a constant specific load rate （CSLR） indentation creep test. Analytical results indicate that both the representative stress and the indentation strain rate become constant after a transient period. Moreover, the FE simulation reveals that both the contours of equivalent stress and equivalent plastic strain rate underneath the indenter evolve with geometrical self-similarity. This suggests that pseudo-steady indentation creep occurs in the region beneath the indenter. The representative points in the region are defined as the ones with the equivalent stress equal to the representative stress. In addition, it is revealed that the proportionality between indentation strain rate and equivalent plastic strain rate holds at the representative points during the pseudo-steady indentation creep of a power law material. A control volume （CV） beneath the indenter, which governs the indenter velocity, is identified. The size of the CV at the indented surface is approximately 2.5 times the size of the impression. The stress exponent for creep can be obtained from the pseudosteady indentation creep data. These results demonstrate that the CSLR testing technique can be used to evaluate creep parameters with the same accuracy as conventional uniaxial creep tests.展开更多
文摘Theoretical analysis and finite element （FE） simulation have been carried out for a constant specific load rate （CSLR） indentation creep test. Analytical results indicate that both the representative stress and the indentation strain rate become constant after a transient period. Moreover, the FE simulation reveals that both the contours of equivalent stress and equivalent plastic strain rate underneath the indenter evolve with geometrical self-similarity. This suggests that pseudo-steady indentation creep occurs in the region beneath the indenter. The representative points in the region are defined as the ones with the equivalent stress equal to the representative stress. In addition, it is revealed that the proportionality between indentation strain rate and equivalent plastic strain rate holds at the representative points during the pseudo-steady indentation creep of a power law material. A control volume （CV） beneath the indenter, which governs the indenter velocity, is identified. The size of the CV at the indented surface is approximately 2.5 times the size of the impression. The stress exponent for creep can be obtained from the pseudosteady indentation creep data. These results demonstrate that the CSLR testing technique can be used to evaluate creep parameters with the same accuracy as conventional uniaxial creep tests.
文摘以热-弹塑性理论为基础,建立了100 mm厚20MnNiMo三维焊接有限元模型,利用ANSYS有限元程序分析了4种约束方式对特厚板焊接残余应力的影响,并通过盲孔法对部分模拟结果进行了试验验证.计算结果表明,约束位置的增加可以使焊接接头残余应力变大.随着约束位置的增加,焊缝区横向应力和热影响区纵向应力由压应力变成拉应力.约束位置越多,残余应力越大,焊接变形越小.模拟结果中,方案A试板边部翘曲变形最大,总变形量为39 mm,方案D变形最小,变形量为0.8 mm.
