Volume 18, Issue 6 (November 1990)
Fracture of Defect Foam Core Sandwich Beams
In the manufacturing of foam core sandwich structures, butt-joints are frequently used within the core. However, inherent flaws may be developed in such joints. Hence areas of stress concentration, such as sharp corners, will exist that may have critical influence on structural behavior. The same type of sharp corners appears in a standard shear test (ASTM C 273) used for determination of shear properties of core materials.
The present paper deals with the analysis of flawed butt-joints in sandwich beams. The analysis is based on a fracture mechanics approach. It is assumed that sharp bi-material corners will be present between the core and face material in the sandwich beam which can be compared with the interface between the core material and the edge plates in the shear test specimen. Such sharp corners develop singular stress fields which are used together with a suitable fracture criterion to predict structural failure in sandwich beams. The results from the standard shear tests for core materials are used to evaluate fracture mechanics parameters. These parameters are used for the prediction of fracture loads of sandwich beams with simulated flaws.