Failure Modes of Perforated Material under Finite Deformation

Local deformation due to the interaction of small scale features such as voids or hard particles is expected to have a significant influence the failure mode of a material. To this end, the fracture pattern of a perforated aluminum sheet is studied experimentally and numerically using finite element models on two different length scales: a full-scale structural model and a local cell model based on large deformation theory. Through appropriate application of boundary conditions, the more efficient local cell model is shown to produce almost the same results as the full structural model. It is also found that the failure path is significantly affected by the loading conditions (uniaxial vs. biaxial) and the hole distribution pattern. By plotting the instantaneous contours of plastic strain rate, the fracture path could clearly be distinguished by the time that the overall engineering strain reaches approximately 3%. This model developed here has great potential to assess the integrity of high pressure components like tubesheet.