Aircraft Windshield Bird Impact Math Model. Part 1. Theory and Application.
Final rept. Jul 75-Dec 77,
DOUGLAS AIRCRAFT CO LONG BEACH CALIF
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This report describes the Bird Impact Math Model IMPACT, a computer program designed especially for the purpose of calculating transient dynamic responses of aircraft windshield and canopy systems, composed of laminated transparencies and support structures, to bird impact. Part I of the report describes the theoretical basis of the program, and presents applications to classical problems and actual windshield systems. The approach is based upon a finite element model of the multilayered transparency and supporting structure, subjected to time-varying loads representing bird impact. The equation of motion for the model is derived, considering geometric and material nonlinearities. The approach to geometric nonlinearities is based upon the method of fictitious forces and deformations. The approach to material nonlinearities is based on the Von Mises yield criterion, and the Pandtl-Reuss equations. The scope of the computing effort is minimized by introducing a modal transformation. The transformed nonlinear differential equation of motion is solved incrementally in time and iteratively within each time step.
- Attack and Fighter Aircraft