The Use of LS-DYNA® Models to Predict Containment of Disk Burst Fragments

Turbomachinery manufacturers commonly test the centrifugal strength of their rotors in a vertical axis spin test, often called a disk burst test. The design of the containment shell that encloses the disk burst event is critical to ensure the safety of the area surrounding the test. A common method used to design the containment shell for a turbine disk burst test is based on the assumption that the kinetic energy lost by the disk fragments during impact is converted into kinetic energy in the containment shell and energy loss to plastic strain and shear failure in the shell. Containment shells are sized such that the energy required to fail the shell material exceeds the kinetic energy loss during impact. This method is approximate because it assumes fully inelastic impacts and does not account for losses due to friction or heat, nor does it account for stress concentrations in the impact zone or complex disk geometries. ANSYS/LS-DYNA was used to develop an analysis method that could provide more accurate predictions of containment failure limits for a wider range of disk and containment geometries. The ANSYS/LS- DYNA models used a piecewise linear plasticity material law with strain rate dependence, segment based eroding contact , nonlocal failure methods, and a consistent element size. Model results showed good correlation with burst test data [1] relative to the prediction of containment, shell perforation, and overall deformation.