Multi-objective optimisation of sandwich panels for lightweight vibroacoustic performance using the direct multisearch algorithm and sublaminate formulation

N.A.R. Costa; A.L. Araújo; J.F.A. Madeira; G. Di Cara; M. D’Ottavio; O. Polit

Key information

Authors:

N.A.R. Costa (Nuno Afonso Ramos Costa); A.L. Araújo (Aurélio Lima Araújo); J.F.A. Madeira (José Firmino Aguilar Madeira); G. Di Cara; M. D’Ottavio; O. Polit

Published in

May 25, 2026

Abstract

This work presents a unified framework for the multi-objective optimisation of lightweight sandwich panels, combining the Sublaminate Generalised Unified Formulation with the Direct MultiSearch algorithm. Structural responses are evaluated through the Sublaminate Generalised Unified–Ritz formulation, while the radiated sound power is computed using a directly coupled Rayleigh-based approach allowing for accurate and computationally efficient assessment of vibroacoustic behaviour across diverse panel configurations. A systematic modelling study identifies the full First-Order Shear Deformation Theory Layer-Wise model as the most suitable kinematic description, achieving accuracy comparable to higher-order formulations at substantially lower cost. Convergence analyses show that twelve Ritz functions per in-plane direction ensure sub-percent error, while a 20 × 20 discretisation of elementary radiators yields stable Rayleigh evaluations with negligible additional runtime. The methodology is demonstrated on a design space defined by six candidate materials (metals, composites, cores, and viscoelastic layers), ply thicknesses, fibre orientations, and symmetry conditions, with Hashin failure criteria enforcing structural integrity. Optimisation results reveal a clear trade-off between mass and vibroacoustic performance: lightweight carbon fibre reinforced plastics-based panels radiate strongly at resonance, whereas heavier, well-damped metallic and hybrid configurations achieve substantially lower sound power levels. Importantly, substituting conventional glass fibre reinforced plastics with natural fibre biocomposites (flax/polylactide, hemp/polylactide, sisal/polylactide) yields no loss of performance, supporting the integration of sustainable materials in advanced engineering design. Overall, the proposed Sublaminate Generalised Unified Formulation–Direct MultiSearch framework thus offers a robust and extensible route for physics-informed optimisation of lightweight vibroacoustic structures.