Overspeed burst of elastoviscoplastic rotating disks – Part I: Analytical and numerical stability analyses

Burst of rotating disks in case of overspeed is investigated. The certification of turbo-engines requires to demonstrate the integrity of disks at higher rotation speeds than the maximum rotation speed reachable in service. The determination of the burst speed by analysis can help to reduce the number of tests required for the certification. This prediction can be established by non-linear stability analyses of finite element simulations. Non-linearities originate from (i) the material behaviour described by elastoviscoplastic constitutive equations, (ii) geometric changes accounted for by the finite strain formulation. In this work, loss of uniqueness and loss of stability criteria from [Hill, R., 1958. A general theory of uniqueness and stability in elastic-plastic solids. J. Mech. Phys. Solids 6, 236–249] are applied. The loss of stability criterion is restricted to the case of rotating disks and compared to several simple widely used material based failure criteria. 3D simulations of rotating metal disks are performed for a given elastoviscoplastic behaviour and the stability criteria are evaluated. The sensitivity of disk stability to material parameters, such as yield criterion, hardening and viscosity is evaluated in the case of a nickel based superalloy.