Rebora Alessandro, Torre Giorgio, Vernassa Gianluca
Department of Mechanical Engineering, University of Genoa, Polytechnic School, Via All' Opera Pia 15A, 16145 Genoa, Italy.
SBM Offshore, 11 Avenue Albert II, 98000 Monaco, Monaco.
Materials (Basel). 2022 Feb 24;15(5):1705. doi: 10.3390/ma15051705.
This paper provides an analytical formula for the theoretical stress concentration factor in a common type of excavation repair for large forgings and castings. Mechanical components obtained with these processes are often subjected to superficial defects. As the rejection of such pieces is out of question, given the relevant size and costs associated with them, usual industrial practice consists in the removal of the defect and a portion of the surrounding material through milling processes. The authors have selected a reference geometry of the excavation to be left on the mechanical pieces, which can be easily controllable in practice by three operating parameters. Then, the domain of existence of such a repair was investigated on a sequence of discrete points, by means of FEA, obtaining for each, the values of the stress concentration factor K. Finally, through polynomial regression, the K functions have been accurately approximated by a sixth degree polynomial formulation, which, given a triplet of dimensional geometric parameters, is able to compute the stress concentration factor K with an error that never exceeds 8%.
本文给出了一种针对大型锻件和铸件常见类型的挖掘修复中理论应力集中系数的解析公式。通过这些工艺获得的机械部件经常会出现表面缺陷。鉴于此类部件的相关尺寸和成本，拒收是不可能的，通常的工业做法是通过铣削工艺去除缺陷及周围的一部分材料。作者选择了留在机械部件上的挖掘参考几何形状，在实际操作中它可通过三个操作参数轻松控制。然后，借助有限元分析（FEA）在一系列离散点上研究了这种修复的存在域，为每个点获得应力集中系数K的值。最后，通过多项式回归，K函数已被精确地近似为六次多项式公式，给定一组三维几何参数，该公式能够计算应力集中系数K，其误差从不超过8%。
