An Efficient Multi-Disciplinary Simulation of Engine Fan-Blade out Event using MD Nastran

This paper presents a multi-disciplinary, integrated implicit-explicit-implicit analysis process for more accurate and efficient simulations of aero engine fan blade-out events using MD Nastran. An FBO event can be extremely nonlinear because of the heavy wide chord fan blades incorporated in the new generation of high by-pass ratio jet engines. These new wide chord blades are used to meet airframe manufacturers’ demand for higher thrust engines with improved performance and optimum weight. Boeing and engine manufacturers use computerized analysis procedures to support the design of both the propulsion system and adjacent wing structures. There have been numerous papers to demonstrate the application of point solutions for fan blade pre-stress, fan blade out analysis and stand-alone rotor dynamics simulation. However, the objective of this paper is to demonstrate the automated, multi-disciplinary simulation capability in MD Nastran to streamline the FBO event simulation which normally consists of three separate steps. Implicit fan blade and possibly gravity and thrust load pre-stress calculations on a fine-meshed finite element model, which are used as initial conditions for Explicit fan blade-out calculations of the initial transient on a fine-meshed finite element model. The forces calculated in this step can be used as loads for a Rotor dynamics simulation for a much longer time, through the engine run-down and the associated transients, using a much coarser mesh. These three steps are accomplished in one common modeling environment, possibly by two different organizations. For example, the first two steps might be done by an aero-engine manufacturer while the third step might be done initially by the airframe manufacturer. It is believed that this process can result in much higher levels of accuracy and dramatically reduce the cost of analysis and design of the propulsion system and wing while still protecting any proprietary information. The example problem that is used in this paper is a representative finite element model of an engine mounted on a wing. 

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