Vibration analysis of honeycomb sandwich plates filled with polyurethane foam

Honeycomb sandwich structures are useful for designing structures that need to be rigid and light-weight. The dynamic properties of honeycomb sandwich structures is important knowledge that should be obtained. These dynamic properties include the honeycomb sandwich structure's natural frequencies and corresponding mode shapes. To confirm the obtained data is correct both experimental and numerical analyses should be performed. To reduce the complexity of the honeycomb layer for numerical analysis, equivalent models exist. This study confirmed the accuracy of the Gibson equivalent model by reproducing numerical analyses found in literature. To improve the mechanical properties of honeycomb sandwich panels, it has been suggested that the honeycomb could be filled with foam. The dynamik properties would need to be found for a honeycomb panel that has been filled with foam. A large cell honeycomb sandwich structure was analyzed both experimentally and numerically. Only the first two natural frequencies could be obtained experimentally. Significant differences were found. The numerical results for the first two natural frequencies were over double the value for the experimental results. A large cell honeycomb sandwich structure was filled with foam and was analyzed both experimentally and numerically. Only the first two natural frequencies could be obtained experimentally. Significant differences were found. The numerical results for the first two natural frequencies were over double the value for the experimental results. A small cell honeycomb sandwich structure was analyzed both experimentally and numerically. Only the first natural frequency could be obtained experimentally. The difference between this result and the numerical result was 14.45%. These two large cell honeycomb sandwich structure dynamic results for the empty and foam filled honeycombs were compared. The difference in the numerical results for the bending modes was minimal. The difference in the experimental results was minimal for the first bending mode.