Response Sensitivity of Typical Aircraft Jet Engine Fan Blade-Like Structures to Bird Impacts.

The response sensitivity of jet engine fan blade-like structures to the details of impact loading were studied. In particular, impacts of birds and ice on jet engines are difficult to model analytically. This report provides guidance in determining the spatical and temporal loading parameters that must be most accurately modeled in a coupled load-response analysis. A finite element model of a cantilever plate was subjected to various spatial and temporal loading details to determine important parameters. The cantilever plate was 7.62 cm 3-inches by 24.46 cm 9.63-inches by 3.81 mm 0.15-inches thick. Applied loads simulated the impact load levels similar to a 85 g 3 ounce bird impacting at 244 msec 800 ftsec. The plate response was monitored by observing deflected shapes at several increments of time during and after impact. The results show that the cantilever plate and presumably a jet engine fan blade are very sensitive to the level of momentum transfer. The detailed spatial and temporal loads that most affect momentum transfer were found to be of particular importance to the structure response. Author