Influence of geometric properties on the natural frequency of bending vibration of polymethacrylamide sandwich composite

The influences of fibre orientation and thicknesses of the skin and the core on the natural frequencies of cantilever polymethacrylamide rohacell sandwich composites (PMRCs) were numerically studied in this work, using the FEA approach.The study established that maximum natural frequency is obtained for the sandwich when the fibre orientation of its GFRP skin is either lateral, (i.e., 0) or longitudinal (90) due to the comparative higher bending stiffness of the skin at these angles.It was also found that the natural frequency increases with increasing core thickness for all bending modes, increases with increasing skin thickness for the fundamental bending mode, and decreases with increasing skin thickness for higher bending modes.It was further found that higher frequencies of bending vibration are obtained in the PMRC sandwich when the PMRF core has a superior thickness ratio of the entire sandwich thickness compared to the GFRP skin.