Ideally, a modal test on a structure would be performed with completely free boundary conditions. This configuration can be approximated by mounting the structure on compliant air cushions, or by suspending it with elastic cords, so that the mounted natural frequency is much smaller that… Read more
This video shows the vibration of consoles in the Mobile Launch Platform underneath the Space Shuttle for the liftoff event. MLP Field Verification Video This video shows the “tennis shoe” method for exciting a rocket vehicle. Saturn V Apollo SA-500F Shake Test at VAB 1966… Read more
Here is a Matlab script which calculates the H1 & H2 frequency response functions for a force and response time history pair. modal_frf.zip It is best suited for the case of random force excitation. It uses ensemble averaging. * * * Here is a Matlab… Read more
This week I participated in an NESC conference in Los Angeles. One of my colleagues brought up the following point. Finite element models are created to represent physical models for analysis purposes. The finite element model natural frequencies can then be compared to data from… Read more