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Proceedings Paper

On the assumption of transverse isotropy of a honeycomb sandwich panel for NDT applications
Author(s): Christoph Schaal; Steffen Tai; Ajit Mal
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Paper Abstract

Due to their excellent strength-to-weight ratio, honeycomb sandwich panels are being increasingly used in lightweight structures, in particular in aircraft and aerospace industry. Delaminations of individual plies in the composite skins or disbonds of a layer in the multi-layer plate structures often remain undetected during visual inspection. Using guided ultrasonic waves, such hidden defects can be detected. For the successful application of ultrasonic nondestructive testing methods, however, wave propagation characteristics have to be well-understood. Recently developed semi-analytical techniques allow for the calculation of dispersion characteristics for many materials. However, the elastic material behavior is often simplified for these calculations. For example, woven composite laminates are modeled as a homogeneous, transversely isotropic plate. While these simplifications only lead to minor errors, the modeling of aluminum honeycomb core sandwich panels with homogeneous, transversely isotropic layers has yet to be validated. In this paper, an efficient numerical approach is used to determine the dispersion characteristics of a honeycomb core layer with and without simplified material behavior. A full 3D-model, including the honeycomb cells, of a small representative volume element of the material is generated using finite elements, and the resulting dispersion curves are compared to the ones obtained from simplified models. In addition to dispersion curves, the displacement fields of the waves are also analyzed.

Paper Details

Date Published: 5 April 2017
PDF: 8 pages
Proc. SPIE 10170, Health Monitoring of Structural and Biological Systems 2017, 1017022 (5 April 2017); doi: 10.1117/12.2260092
Show Author Affiliations
Christoph Schaal, California State Univ., Northridge (United States)
Univ. of California, Los Angeles (United States)
Steffen Tai, Univ. of California, Los Angeles (United States)
Ajit Mal, Univ. of California, Los Angeles (United States)

Published in SPIE Proceedings Vol. 10170:
Health Monitoring of Structural and Biological Systems 2017
Tribikram Kundu, Editor(s)

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