Influence of Integrating Stiffening Grid Honeycomb Structure in Syntactic Foam Core on Structural Vibration Response of Sandwich Composites

Background: High strength-to-weight ratio and high stiffness-to-weight ratio are the potential benefits of syntactic foam core sandwich composite for structural applications. However, these composite structures may encounter problems in correlation with vibration because of poor quality-factor and leads to poor structural performance. Purpose: Present investigation focused on improving the structural performance of syntactic-foam core sandwich composites by enhancing their quality-factor. This is achieved by integrating stiffening grid honeycomb structure in syntactic foam during manufacturing. Methods: The investigation has been restricted to the flexural vibrations of sandwich composite beams, which are the predominant mode of vibration in many practical vibration scenarios. Experimentally modal analyses are carried out to analyze the vibration signals under different boundary conditions. Initially suitable theoretical model is used to validate the experimental results. Results: Results obtained from the investigation reveals that the stiffened syntactic foam core sandwich composite shows excellent vibration attenuation characteristics. This behaviour can be attributed to the presence of stiffening grid honeycomb cells in the syntactic foam core. Each cell wall of the honeycomb grid leads to the interference between the incident wave and the reflected wave under vibrating condition. Further, the vibration response characteristics are significantly affected by the orientation and boundary conditions. It is observed that the increase in the frequency of vibration, better quality factor and minor decrease in the damping ratio of sandwich composites are considerably influenced by the confined state of syntactic foam in the hexagonal cell size of honeycomb stiffening grid structure. Conclusion: The improvement in quality factor highlights the significant influence of continuum characteristics of honeycomb grid stiffened syntactic-foam cored sandwich composites.