Energy-based reformulated Craig-Bampton method for multiple flexural subsystems connected at a junction with low impedance mismatch

Whereas the coupling between modes of two different subsystems is well-resolved in vibroacoustic energy-based methods, the situation becomes more intricate when several subsystems get connected at a common junction. In statistical energy analysis (SEA), the modal formulation is replaced by the travelling wave approach to solve the problem. However, this is not a viable option for other energy-based methods, like the statistical modal energy distribution analysis (SmEdA), and a modal coupling scheme is required for them. If there is a strong impedance mismatch between the multiple connected subsystems, the displacement-stress dual formulation offers a proper way to address the situation. Unfortunately, the latter fails if all involved subsystems have similar stiffness. In this work, the feasibility of the Craig-Bampton (CB) method to address such circumstance is explored. It is shown that the original CB technique does not fulfill the modal coupling assumptions of energy-based methods, so it is suggested to reformulate it to partially mitigate the problem. Numerical tests on a benchmark test are carried out to validate the proposal. The benchmark consists of a floor coupled with two walls at right angle, and it is analyzed for different impedance mismatch conditions.