Paper number 543

A COMPARATIVE STUDY OF MODE I FATIGUE CRACK PROPAGATION IN FOAM CORES FOR SANDWICH STRUCTURES BY USING DIFFERENT TEST SPECIMENS

Andrey Shipsha, Magnus Burman, Dan Zenkert

Department of Aeronautics
Division of Lightweight Structures
Royal Institute of Technology
100 44, Stockholm, Sweden

Summary

This paper summarises results on mode I fatigue crack growth (FCG) in foam core materials for sandwich structures. The studies deal with characterisation of the FCG in the face/core interface in sandwich beams and in the virgin foam core. The core material properties, test specimens and experimental procedures are briefly described. Stress intensity factors (K in the vicinity of the crack tips are computed using the finite element method. The obtained FCG rates da/dN in the investigated specimen configurations are combined in standard da/dN versus (K curves). Fatigue behaviour of the cellular foams appear to conform to the classical Paris' law. The influence of face/core interface on mode I FCG rates is discussed in comparison to the FCG rates in the virgin core. The FCG rates in the face/core interface in sandwich beams are verified using the Tilted Debond Sandwich (TDS) specimen.

Keywords

fatigue, crack growth, fatigue threshold, foam core, sandwich structures.