Abstract There is a growing interest on the Small Punch Test (SPT) and its many applications in a broad range of industries and sectors. The miniature volume of the SPT specimen eases the mechanical characterization of components and structures when standard tests are impracticable. But this miniature test is limited for one of its more constraining requirements: the material isotropy. Since this test subjects the material to triaxial stress and strain fields, isotropy is necessary to compare the resulted data from SPT with the standard tests, which generally show uniaxial stress fields. Another key element of this question is that initially, isotropic material can lose this property due to a cold pre-straining process and the existence of the Bauschinger effect. In this investigation, a numerical study with the finite element method was performed to understand the influence of pre-straining and the Bauschinger effect in yield strength and ultimate tensile strength estimation with the SPT. This study concludes that in the absence of isotropy, generated by a pre-straining, the SPT estimated a mean value of the principal yield strength components of the yield surface. It is also verified that presence of pre-straining in the SPT specimens invalidated their use to calculate the coefficients of the correlation equations for yield strength estimation.

中文翻译：

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使用小冲孔试验估计屈服和极限抗拉强度的偏差：预应变和包辛格效应影响的数值分析

摘要 人们对小打孔测试 (SPT) 及其在广泛行业和部门中的许多应用越来越感兴趣。当标准测试不可行时，SPT 样品的微型体积可以简化组件和结构的机械表征。但这种微型测试受限于其更具约束性的要求之一：材料各向同性。由于该测试使材料经受三轴应力和应变场，因此需要使用各向同性将 SPT 的结果数据与标准测试进行比较，标准测试通常显示单轴应力场。这个问题的另一个关键因素是，最初，由于冷预应变过程和包辛格效应的存在，各向同性材料可能会失去这种特性。在这次调查中，使用有限元方法进行了数值研究，以了解预应变和包辛格效应对使用 SPT 估计屈服强度和极限抗拉强度的影响。该研究得出的结论是，在不存在由预应变产生的各向同性的情况下，SPT 估计了屈服面的主要屈服强度分量的平均值。还验证了 SPT 试样中预应变的存在使它们无法用于计算屈服强度估计的相关方程的系数。SPT 估计了屈服面的主要屈服强度分量的平均值。还验证了 SPT 试样中预应变的存在使它们无法用于计算屈服强度估计的相关方程的系数。SPT 估计了屈服面的主要屈服强度分量的平均值。还验证了 SPT 试样中预应变的存在使它们无法用于计算屈服强度估计的相关方程的系数。