Aerospace Defense

Investigation and Comparison of Porous Core and Viscoelastic Core on the Natural Frequencies of Sandwich Structures Aiming to Enhance the Strength and Safety of Defensive Structures

Document Type : Original Article

Authors

Aliasghar Naderi 1
Hadi Teymouri 2
Mehdi Pourseifi 1

1 Faculty of Engineering and Aviation, Imam Ali Officer University, Tehran, Iran

2 Department of Mechanical Engineering, Faculty of Mechanical Engineering, University of Tabriz, Tabriz, Iran

Abstract
The security and survivability of defensive structures against extreme dynamic loads such as blast waves and impacts is a fundamental priority in modern design. Sandwich panels, due to their exceptional strength-to-weight ratio and high energy absorption capacity, are among the primary candidate materials in this field. This research investigates and compares the influence of two widely used core types the porous core and the viscoelastic core on the natural frequencies of a sandwich beam structure. The main objective of this study is to assess the potential of these cores to enhance the strength and safety of defensive structures through the analysis of their vibrational behavior. The present research employs analytical modeling to perform the natural frequency analysis. Using three-layer sandwich beam theory and applying Hamilton's principle, the governing equations of the system are derived. The resulting equations are complex partial differential equations (PDEs). To solve these equilibrium equations, the semi-analytical Navier method is utilized in the spatial domain. To validate the accuracy of the obtained results, comparisons are made with existing solutions for specific cases. Finally, the influence of various parameters such as carbon nanotube volume fraction, porosity coefficient, porosity distribution pattern, geometric and dimensional ratios on the natural frequencies of the sandwich structure is examined. This investigation covers structures with both porous and viscoelastic cores and nanocomposite face sheets. A key finding of this research is that, in most instances, the viscoelastic core exhibits higher natural frequencies and greater strength compared to the porous core.

Keywords

Natural frequency
Porous core
Viscoelastic core
sandwich beam
Hamilton'
s principle

Subjects

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Aerospace Defense
Volume 4, Issue 2
Spring 2025
Pages 1-26

  • Receive Date 02 August 2025
  • Revise Date 19 August 2025
  • Accept Date 10 September 2025

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