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Penetrating Impact Strength of Sandwich Panels — Meaningful Test Method and Simplified Prediction

  • Martin Hildebrand
Conference paper

Abstract

This paper proposes a test method which is comprehensive enough to be able to quantify the impact strength, according to various definitions, of a sandwich and, most importantly, be applicable to sandwich panels of various types and scales. These findings are based on the results of a penetrating impact test series using three different test methods: The standardised ISO 6603 method and two non-standardised methods. The first non-standardised method uses a pyramid-shaped impactor instead of the cylindrical impactor used in the ISO 6603 method and in the second the impact test is performed quasi-statically using a cylindrical impactor.

The results obtained with the three test methods lead to a different ranking in impact strength of the panels. Hence, impact test results obtained with different test methods are not even qualitatively comparable.

The pyramid-shaped impactor is able to generate clearly more failure modes than the cylindrical impactor in the ISO 6603 method. Therefore, it is considered to be of more practical value for determining the impact strength of FRP-sandwich structures.

Additionally, a simplified approach to predict the impact strength of FRP-sandwich panels in respect to full penetration is presented. The method is semi-empirical and allows one to predict the absorbed energy at penetration of the inner face without the need for exotic input values. The empirical part of the method lies in the fact that certain damage modes are assumed to occur during the impact. These assumed damage modes have been observed in many earlier experiments. The accuracy of the method is reasonably high, in most cases better than ±30%.

The semi-empirical prediction method is particularly useful during the design stage of sandwich structures due to its reasonable accuracy and the fact that the needed input values are usually known at this stage.

Keywords

Failure Mode Impact Strength Transverse Shear Sandwich Structure Sandwich Panel 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media Dordrecht 1998

Authors and Affiliations

  • Martin Hildebrand
    • 1
  1. 1.VTT Manufacturing TechnologyFinland

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