Dynamic Loads in the Fan Containment Structure of a Turbofan Engine

In accordance with the FAA certification requirements, all modern commercial turbofan engines must successfully demonstrate its ability to withstand a fan blade-out (FBO) event through actual test. Possibility of losing a rotating fan blade from a running engine is a flight safety consideration, which must be addressed during the design phase of the engine. A typical fan blade-out event involves very complex nonlinear transient dynamics with large deflection of the release blade and rigid body rotation of the trailing blade as well as progressive failure and fragmentation of various components. Due to the nature of the impact type loading, the solution to the problem should also address dependence of the material behavior such as yield strength as a function of strain rates. In short, the transient dynamic analysis of a fan blade-out event highlights the complexity of the numerical technique, which includes all the nonlinearities of structural dynamics: plastic behavior of the materials, large displacements, and contact interaction between structural elements. In this paper, we present the results of a LS-DYNA simulation of a FBO event on a full-engine analytical model, which covers both the primary as well as secondary damages.