Vibration and acoustic properties of composites with embedded lithium-ion polymer batteries

Composite structures containing lithium-ion polymer (LiPo) batteries are being developed for electrical energy storage in motor vehicles and other applications. This paper presents an experimental and numerical study into the effect of embedding (LiPo) batteries into carbon fibre laminates and sandwich panels on the vibration and acoustic properties. The vibration responses (modal frequencies, damping) were measured experimentally using Laser Doppler vibrometry and calculated numerically using finite element modal analysis. The results reveal that careful placement of LiPo batteries within composite structures is needed to control the vibration properties. Embedding batteries at the nodal points increases the vibration bending damping ratio for modes II and III, with improvements of up to 220% (mode II) and 310% (mode III) for the laminate and sandwich composite, respectively. LiPo batteries also improve the acoustic performance by increasing the coincidence frequency and decreasing the wavenumber amplitude at frequencies above the first vibration bending mode. The results indicate that the judicious placement of embedded LiPo batteries can improve the vibration damping properties of both carbon fibre laminates and sandwich composites.