SYMPOSIA PAPER Published: 01 January 1992

Effect of Manufacture-Induced Flaws on the Strength of Foam Core Sandwich Beams


In the manufacture of foam core sandwich structures, the faces are bonded to the core, and blocks of foam core material are bonded to each other in order to obtain the required thickness. Core material blocks are also joined lengthwise in the production of large and/or curved structures, using so called butt joints. However, in the manufacturing process, flaws may occur. Debonding in the adhesive joints acts as cracks, and sharp corners will be the result of an absence of filler material in a butt joint. The present paper deals with methods for the prediction of the reduction in load-bearing capacity of foam core sandwich beams due to these flaws. A fracture mechanics approach is used, including both analytical methods and finite element analysis. Fracture toughness data of the materials and wedge geometries are found from simple specimens. Full-scale tests are performed using beams with prefabricated flaws for verifying the analysis. The predictions agree well with the experimental results. The reduction in load-bearing capacity is as much as between a factor of 1.5 to 4.9 for different geometries and flaw types.

Author Information

Zenkert, D
The Royal Institute of Technology, Stockholm, Sweden
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Developed by Committee: D30
Pages: 137–151
DOI: 10.1520/STP14571S
ISBN-EB: 978-0-8031-5190-1
ISBN-13: 978-0-8031-1474-6