Signal Processing, Wavelets and high-speed Image Interpretation of Bird Impact

  • K. Karthikeyan National Aerospace Laboratory, Bengaluru
  • S. Ramachandra Gas Turbine Research Establishment, Bengaluru
  • S. Paul Vizhian †University Visvesvaraya College of Engineering, Bengaluru
  • Satish Chandra National Aerospace Laboratory, Bengaluru
Keywords: Bird impact, image processing, signal processing, wavelets, simulation modules


Bird impact on aircraft has been well documented and has been of interest for researchers in aircraft design. The process, though of very short duration, is complex in nature. A bird, which can be treated as a soft body behaves more like a fluid at high-speeds. When aircraft components become targets of bird strikes, the impact can have consequences for safety, and hence the study of the phenomena has engineering implications. In this paper, strain signals from a specially instrumented stiff fixture, high-speed imaging and wavelets are used to describe the nature of the phenomenon. Gelatin-based artificial birds were impacted on the fixture fired through an air gun at two different velocities. high-speed imaging showed different behaviours with a rebound at low-velocity (~50 m/s) and a flow behaviour at high-velocity (~100 m/s). High sampling data acquisition was used to measure the dynamic strain exerted on the fixture during bird impact. Time histories of strain signals obtained in the raw form were processed to get a Fourier spectrum and continuous wavelet transform to gain more information about different frequency patterns and the temporal distribution of the frequencies, when such impacts occurred. The frequency content for low-velocity and high-velocity impacts is characterised. It can be noted that the behaviour as described by earlier researchers was seen here as well at higher velocities, though at lower velocities, the bird behaved more like a solid. Many aircraft have approach speeds that are about 60 m/s rather than 100-200 m/s, making it important to study behaviour at lower velocities as well. The short time interval events identified in the signals provide insight into the nature of the loads on targets. This information can aid in tuning simulation models of the birds which use Lagrangian, Eulerian and smooth particle hydrodynamic models.

Defence Science Journal, 2011, 61(1), pp.62-71, DOI:

Author Biographies

K. Karthikeyan, National Aerospace Laboratory, Bengaluru

Mr Karthikeyan K. obtained MS (Aerospace Engineering) from Indian Institute of Technology Madras in 2004. At present, he is pursuing doctoral studies at Cambridge University Engineering Department. His research interests are Composites, Impact mechanics and Digital image processing.

S. Ramachandra, Gas Turbine Research Establishment, Bengaluru

Mr Ramachandra holds a Masters degree in Mechanical Engineering from IISc and is currently working as Scientist 'F' at Gas Turbine Research Establishment (GTRE), Bengaluru. He has over 23 years experience in the field of Impact Mechanics, Structural analysis and testing of aero engine components. He has more than 35 publications in International Journals and Conferences. He is Fellow of Institution of engineers and Institution of Production engineers. He has worked for certification programs of Kaveri engine, and other major national projects, viz. ALH, LCA, SARAS aircraft and AEW&C. His other fields of activities include high temperature PMC's and CMC's for aero engines.

S. Paul Vizhian, †University Visvesvaraya College of Engineering, Bengaluru

Dr S. Paul Vizhian is currently a Professor of Mechanical Engineering at the University Visveswaraya College of Engineering, Bengaluru. He obtained his Bachelor, Masters and PhD from the University of Bengaluru. He is Fellow of Institution of Production Engineers and life member of Institution of Engineers and. ISTE. He has more than 25 years of academic experience. He has more than 50 publications in National and International Conferences and Journals. His main areas of interest are Experimental Mechanics and composites.

Satish Chandra, National Aerospace Laboratory, Bengaluru

Dr Satish Chandra is presently the Project Director, NCAD and is holding additional charge of Head, Structural Technologies Division, at National Aerospace Laboratories and specializes in impact and crashworthiness. He has a PhD from the University of Bristol, England. He has published over 100 papers and technical reports. He has over 25 years of experience in the field.

How to Cite
Karthikeyan, K., Ramachandra, S., Vizhian, S., & Chandra, S. (2010). Signal Processing, Wavelets and high-speed Image Interpretation of Bird Impact. Defence Science Journal, 61(1), 62-71.
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