Study on hybrid surface connections and noise reduction mechanisms based on a hybrid FE-SEA model

To tackle full-frequency noise prediction and control challenges for automotive NVH optimization, the present work investigates the noise-reduction mechanisms of hybrid surface connections under the classical hybrid FE-SEA framework. The blocked sound field and free sound field surface connection models are introduced into vehicle vibro-acoustic coupling analysis to define their structural boundary applicability. From energy-path suppression and vibration optimization viewpoints, this work quantifies how core parameters including coupling loss factor, internal loss factor, and modal density affect acoustic transmission, and concludes targeted control approaches for three dominant energy transfer routes. A coupled FE-plate–SEA-cavity model is established and validated experimentally to verify the proposed analytical framework. Three prevailing noise-reduction solutions (additional surface mass, constrained layer damping, and porous absorption) are compared for their frequency-dependent performance. Results show constrained layer damping delivers peak 18 dB attenuation near the 160 Hz resonance via shear energy dissipation within 40–250 Hz; porous absorbers cut reverberant energy by up to 10 dB across 200–2000 Hz relying on viscoelastic and thermal effects; extra surface mass works merely within 40–80 Hz and risks mode shift and emergent resonances. This research supplies quantified data and simulation guidance for full-spectrum NVH optimization of automobile structures.