Deriving transmissibility functions from finite elements for specifications
AIAA Scitech 2021 Forum
This work explores deriving transmissibility functions for a missile from a measured location at the base of the fairing to a desired location within the payload. A pressure on the outside of the fairing and the rocket motors excitation creates an acceleration at a measured location and a desired location. Typically, the desired location is not measured. In fact, it is typical that the payload may change, but measured acceleration at the base of the fairing is generally similar to previous test flights. Given this knowledge, it is desired to use a finite element model to create a transmissibility function which relates acceleration at the previous test flights measured location at the base of the fairing to acceleration at a location in the new payload. Three methods are explored for deriving this transmissibility, with the goal of finding an appropriate transmissibility when both the pressure and rocket motor excitation are equally present. A novel method termed the Harmonic method is introduced and unfortunately found not to be as accurate as standard methods. However, the standard methods also do not perform particularly well for the combined loading of aerodynamic pressure and rocket motor excitation.