An Experimental and Numerical Study of Ballistic Impacts on a Turbine Casing Material at Varying Temperatures

An experimental and numerical study of ballistic impacts on steel plates at various temperatures (700 °C, 400 °C and room temperature) has been carried out. The motivation for this work is the blade-off event that may occur inside a jet engine turbine. However, as a first attempt to understand this complex loading process, a somewhat simpler approach is carried out in the present work. The material used in this study is the FV535 martensitic stainless steel, which is one of the most commonly used materials for turbine casings. Based on material test data, a Modified Johnson-Cook (MJC) model was calibrated for numerical simulations using the LS-DYNA explicit finite element code. To check the mesh size sensitivity, 2D axisymmetric finite element models with three different mesh sizes and configurations were used for the various temperatures. Two fixed meshes with 64 and 128 elements over the 2 mm thick plate and one mesh with 32 elements over the thickness with adaptive remeshing were used in the simulations. Both the formation of adiabatic shear bands in the perforation process and the modeling of the thermal softening effects at high temperatures have been found crucial in order to achieve good results.