Definition of SEA models for structures with restricted accessibility

The definition of an SEA model is usually focused on the determination of the SEA loss factors that are related to the power balance between SEA subsystems. There are several techniques available to perform this task that is usually referred as Experimental SEA. One of the most widely used techniques that has led to the definition of a set of different experimental procedures, is the Power Injection Method. This method is based on the experimental determination of several independent power balances for the system under study in order to calculate the whole set of SEA loss factors. For complex structures, some elements may have reduced accessibility or not accessibility at all. This fact means that it may be impossible to measure their response or to apply an external load in order to obtain one of the independent power balances required. Two methods are presented to analyse such systems whose study through the Power Injection Method is not feasible. Their application is shown through a study case: an L-shaped structure composed of two sandwich panels in a reverberant chamber. Results show that the methods presented allow determining the system SEA loss factors if one of the subsystems considered cannot be excited.