For my group's research, we need to perform a modal analysis on a square aluminum bar with small pillars attached to the top of it (one unit cell has a base cube of 6x6x6 cm and a pillar of 1.5x1.5x3 cm, and there will be 15+ unit cells in our baseline model), and due to some limitations with money and time, we are having a debate over whether or not we should glue the pillars to the bar, or take the time and money to produce a solid piece.
My question is: Will the resultant FRF graphs from a modal analysis where the structure is simply glued together be acceptable to within a reasonable margin of error from if we were to perform the analysis with a solid piece?
Note: we are NOT looking into ANY strength properties, we are simply looking at the FRF graphs to attempt to create some band gaps in a few specific frequency ranges. Our range of frequencies that this will be measured at are between 10 and 8000 Hz. The point of this specific research is to test a theory and produce some baseline results, so we are not expecting perfection yet. If we can prove the theory, and then can get a grant, then we will be producing the solid model with a lot of precision.
I hope you guys can help us solve this debate, I appreciate any and all help you can give!