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Balasubramaniam, Krishnan
- Propagation of the Fundamental Symmetric Lamb Mode in a Symmetrically Delaminated Composite Laminate
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Authors
Affiliations
1 Composites Research Center, R&DE(E), Defence Research and Development Organization, Pune, IN
2 Centre for Non-Destructive Evaluation, Indian Institute of Technology, Chennai, IN
1 Composites Research Center, R&DE(E), Defence Research and Development Organization, Pune, IN
2 Centre for Non-Destructive Evaluation, Indian Institute of Technology, Chennai, IN
Source
International Journal of Vehicle Structures and Systems, Vol 4, No 3 (2012), Pagination: 102-106Abstract
In this paper, a study on the propagation of the fundamental symmetric Lamb mode (So) in a symmetrically delaminated glass/epoxy composite laminate is presented. It was found that when So mode is incident at the front and rear edges of a symmetric delamination, it generates Ao mode. This mode is exclusively confined to the sub-laminates. It was also observed that, during the interaction of the generated Ao mode with the edges of delamination, it, in turn generates So mode. Thus, So mode and mode converted Lamb modes undergo multiple mode conversions in the sub-laminates. The only mode that propagates in the main laminate is So. A signal-processing scheme based on the time-frequency spectrographic analysis was utilized to identify the wave groups propagating in the main and sub-laminates.Keywords
Lamb Wave, Delamination, Composite Laminate, Wavelet Transform.
- Periodicity dependent properties of holey phononic crystals
Abstract Views :161 |
PDF Views:0
Authors
Affiliations
1 Chaitanya Bharathi Institute of Technology, Hyderabad-500 075, Telangana, India., IN
2 Centre for Non-destructive Evaluation and Department of Mechanical Engineering, Indian Institute of Technology- Madras, Chennai-600 036, Tamil Nadu, India., IN
1 Chaitanya Bharathi Institute of Technology, Hyderabad-500 075, Telangana, India., IN
2 Centre for Non-destructive Evaluation and Department of Mechanical Engineering, Indian Institute of Technology- Madras, Chennai-600 036, Tamil Nadu, India., IN
Source
Journal of Pure and Applied Ultrasonics, Vol 44, No 1-2 (2022), Pagination: 37-40Abstract
Phononic crystals, which are structures with periodicities on the scale of the incident sonic wavelength, are of much interest due to the potential for new properties, such as band gaps and high-efficiency transmission. The phononic properties of holey structures have been particularly studied because of their ease of fabrication and scalability. Recently our group has demonstrated super resolution imaging using structured holey lenses. However, the resolution capacity of phonic crystals having a periodic arrangement of regular holes is limited by the Wood anomaly, at which some of the wave field components vanish from the transmission spectrum. This paper discusses an alternative approach to overcome the Wood anomaly, using aperiodic lenses. We show deep subwavelength imaging (λ/32) of a surface notch in a mild steel sample using the proposed unstructured phononic holey lens.Keywords
Periodicity, Phononic Crystal, Super Resolution, Unstructured Phononic Lens, Wood Anomaly.Full Text
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