All-composite honeycomb core sandwich structures: Master curves for stiffness-based design

Abstract

Composite-walled hexagonal honeycomb core is considered for stiffness-based design. It is shown that the torsional and flexural stiffnesses of its all-composite sandwich may be 3- and 8-times higher, respectively, compared to structural foam core sandwich panel. This increase is attributed to an order of magnitude higher transverse shear resistance of composite-HC core. All-composite design can also outperform traditional aluminum core sandwich by about 25% and 60% increase in stiffness values under torsional and flexural loading. The results also reveal that stiffness of sandwich panel configurations of an arbitrarly fixed total structural weight can be mapped into unified “master design curves”. They suggest skin-to-core weight ratio for optimal flexural and torsional stiffnesses. The ratios herein are 1.3 and 2.6 respectively. The penalty of one on the other is about 8–10%. The ratio of 1.85 is the best compromise between the flexural and torsional stiffnesses reducing the trade-off to 2–3%.

Keywords

• Maximum Flexural and Torsional Rigidities
• Material Selection
• Effective Moduli
• Modal Analysis
• Variable Loading Cases
• Manufacturing Constraints