Journal of Mechanical Design and Vibration
ISSN (Print): 2376-9564 ISSN (Online): 2376-9572 Website: Editor-in-chief: Shravan H. Gawande
Open Access
Journal Browser
Journal of Mechanical Design and Vibration. 2019, 7(1), 16-20
DOI: 10.12691/jmdv-7-1-2
Open AccessArticle

Free Vibration Studies of Woodpecker Inspired Layered Shock Absorbing Structure

Dr. B Biju1, , Anandu Ramesh1, Aparna R Krishnan1, Aravind G Nath1 and Christy Francis N J1

1Department of Mechanical Engineering, Mar Athanasius College of Engineering, Kerala, India 686 666

Pub. Date: July 15, 2019

Cite this paper:
Dr. B Biju, Anandu Ramesh, Aparna R Krishnan, Aravind G Nath and Christy Francis N J. Free Vibration Studies of Woodpecker Inspired Layered Shock Absorbing Structure. Journal of Mechanical Design and Vibration. 2019; 7(1):16-20. doi: 10.12691/jmdv-7-1-2


A woodpecker can drum the surface of a tree at a rate of 18 to 22 times per second with a deceleration of 1200g without experiencing any blackout or brain damage. A woodpecker is able to do this because of its unique head structure; beak, hyoid, spongy bone and skull bone with cerebrospinal fluid. Based on this concept, a bio inspired layered shock absorbing structure was fabricated. The three layer structure consists of steel as outer layer, aluminium as intermediate layer with viscoelastic material in between and a core containing gel/beads were used. The shock absorbing structure was then subjected to free vibration analysis by considering it as cantilever beam with fixed free boundary condition. The natural frequencies of the structure including the fundamental mode and higher modes were estimated using vibration measuring apparatus integrated with software. Experimental results of the shock absorbing layers were compared with numerical results estimated using commercial finite element package ANSYS. Noticeable variation in the frequency can be associated with the shell mode vibration of the cylindrical shape and delamination effect in the layered structure. The free vibration studies are useful in estimating the damping characteristics of woodpecker beak inspired layered structure and can find applications in hybrid shock absorber design.

free vibration woodpecker beak layered structure natural frequency

Creative CommonsThis work is licensed under a Creative Commons Attribution 4.0 International License. To view a copy of this license, visit


Figure of 9


[1]  May P R A, Fuster J M, Newman P and Hirschman A, (1976), Woodpeckers and head injury, Lancet, 307, Issue 7957, P454-455.
[2]  Sang-Hee Yoon, Sungmin Park, (2011), A mechanical analysis of woodpecker drumming and its application to shock-absorbing systems (2011), Bioinspiration &Biomimetics, Volume 6, 016003 (12pp).
[3]  Sang-Hee Yoon, Jin-Eep Roh, Ki Lyug Kim, (2009), Woodpecker-inspired shock isolation by microgranular bed, Journal of Physics. D: Applied Physics, Volume 42 035501 (8pp).
[4]  S. P. Chaphalkar, Subhash. N. Khetre, Arun M. Meshram, (2015), Modal analysis of cantilever beam Structure Using Finite Element analysis and Experimental Analysis, American Journal of Engineering Research, Volume 4, Issue-10, pp-178-185.
[5]  ANSYS 15.0 User Reference Manuel.
[6]  Edgar Gutierrez, Alex Groisman, (2011), Measurements of Elastic Moduli of Silicone Gel Substrates with a Microfluidic Device, Plos One 6(9), e25534.
[7]  U. Stirna, I. Beverte, Vladimir Yakushin, Ugis Cabulis, (2011), Mechanical properties of rigid polyurethane foams at room and cryogenic temperatures, Journal of Cellular Plastics 47(4): 337-355.
[8]  Robert D. Blevins, Formulas for Dynamics, Acoustics and Vibration, Wiley Series, pp 237-243, (2016).