Hybrid deterministic-statistical modeling of stiffened plate structures

Abstract

Statistical energy analysis (SEA) is based on equations of power balance between resonant subsystems, and, given the excitation power input to the system, the resulting average vibration level in each subsystem may be calculated. However, due to the low modal density of beams, SEA cannot fully account for energy flow along stiffening members of typical stringer-skin constructions used in the aerospace and marine industries. Thus, in a conventional SEA model of a built-up structure to which excitation is applied through a stiffening member, it is not clear how to compute the power input to each resonant subsystem and the response of the nonresonant stiffening framework. The problem is addressed by using a coupled deterministic-statistical approach: the stiffeners are modeled deterministically, while the reverberant two-dimensional structural components are modeled as power absorbing systems, in which the power is carried by statistical cylindrical waves propagating towards an energy sink. This power is then reinjected into an SEA model of the system. The numerical features of the method and some new results from a beam-plate system (compared with Monte Carlo simulations) are presented. The results indicate that the SEA power input as well as the response of the stiffener is modeled correctly.