Browse Publications Technical Papers 2015-01-2345

Vibro-Acoustic Properties of a Very Long Flax Fibers Reinforced Thermoset “Flaxpreg” Light Sandwich 2015-01-2345

The Flaxpreg is a green and light very long flax fibers thermoset reinforced sandwich, which can be effectively used as multi-position trunk loadfloor or structural floor in the passenger compartment of a vehicle. The prepreg FlaxTapes of about 120 g/m2 constituting the skins of the sandwich, are unidirectionally aligned flax fibers tapes, with acrylic resin here, easily manipulable without requiring any spinning or weaving step and thus without any negative out of plane crimping of the almost continuous flax fibers.
Thanks to their very low 1.45 kg/dm3 density combined with an adaptive 0°/90°/0° orientation of the FlaxTapes (for each skin) depending on the loading boundary conditions, the resulting excellent mechanical properties allow a - 35% weight reduction compared to petro-sourced Glass mat/PUR sandwich solutions (like the Baypreg). The vibro-acoustic damping properties of these FlaxTape skins are remarkable with an almost 2 % Damping Loss Factor, whereas glass/resin or carbon/resin composites lie at around 0.15%.
This study presents a comprehensive measurement and simulation correlation campaign of the vibro-acoustic properties of the Flaxpreg sandwich, namely its Damping Loss Factor and its airborne Transmission Loss with and without necessary noise treatments to ensure a good NVH comfort. Various simulation methods from the simplest models to the most complex ones will be compared to one another and to measurements: namely analytical sandwich models implemented in SEA softwares, Transfer Matrix Methods sandwich formulations as well as Finite Element/Boundary Element detailed or homogenized models including poroelastic materials…


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