Abstract
The present paper is concerned with the problem of mode III fracture in foam core composite sandwich beams. Three-dimensional linear-elastic finite element simulations were performed of sandwich beams with a crack in the mid-plane of the core. The load of the sandwich beam was chosen such that the cross-sectional bending moment in the arms at the crack front was reduced to zero in order to minimize the mode II fracture. Within the finite element analysis, the fracture was studied in terms of the strain energy release rate using the virtual crack closure technique. The calculations revealed that pure mode III loading conditions were induced along the crack front, except a small zone near the free edges of the sandwich beam cross-section, where mode II component of the strain energy release rate was also found. The influence of the sandwich core material on the mode III fracture was analyzed. For this purpose, three sandwich beam configurations were considered (it was assumed that the sandwich core was made by three different rigid cellular foams). It was found that the strain energy release rate decreases with increase of the sandwich core density.
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