Assessment of Equivalent Properties for Flat Multilayered Panels 2024-01-2943

The use of lightweight complex heterogeneous structures increased during the last years principally in the transportation sector (i.e., aviation and trains). This sector's technology enhancement pursues reducing long-term CO2 emissions and increasing efficiency. Lightweight structures may have poor vibro-acoustic behavior and in designs with complex shapes and material heterogeneities, its vibro-acoustic modeling brings new challenges in terms of accuracy and computational cost. Techniques such as model order reduction, homogenization, mesh and meshless methods (with and without periodicity conditions) and energy methods are typically employed to tackle this problem. Within homogenization techniques, an equivalent properties strategy can be utilized to equivalently represent complex structures into more simple ones (for example, a single layer panel). The latter is named equivalent structure or carrier and it is responsible for representing certain quantities of the original structure. This work aims to stress the use and limitations of a single layer thin orthotropic plate when utilized as a carrier of multilayered structures. Limitations provide insight into the potential applicability of this strategy in complex structures. Equivalent in-plane and out-of-plane stiffness coefficients are obtained from the heading-angle-dispersion curves of the reference structures. With the equivalent properties, the equivalent global stifness matrix is built and utilized to calculate different vibro-acoustic indicators. To verify the effectiveness of the strategy, different comprehensive examples of multilayered structures, including with added Noise control Treatments, are presented. The particular case of highly damped sandwich structures is addressed. A forced analysis is performed for a carrier with and without damping and different energetic quantities (indicators) are computed and compared with reference solutions.