Stress Distribution Investigation at the Tapered Sandwich Endings

Abstract

One of the typical sandwich ending is tapered transition to a solid laminate, which causes significant stress distribution changes. The reviewed articles show that tapered area causes increase in the shear stress in the core, increase of the axial forces in the facesheets and local bending at the fork point, at points of the tapering angle change, and at ply drop positions. Most of the studies gave attention to the endings without reinforcing. During Erasmus+ internship at KTH 2D model of the tapered ending with reinforcing plies, various geometry and resin filler in the core tip was investigated to see the influence on the stress distribution. It was found that tension load case is not as critical as bending load case. Increasing of the solid laminate thickness, adding plies and inserting a short resin or adhesive filler into the core tip area lead to significant stress reduction, whereas in the transition point, from tapering to constant thickness sandwich, increasing radius is more efficient than reinforcing plies in regard to reduce stress concentration.

Composite sandwich panel closeout analysis and test

“…The functionally graded densified core material was developed by in-plane crushing of regular periodic honeycomb cores. In recent years, a 2D model with isotropic core and conventional shell elements for facesheets 20 was used to study the influence of reinforcing plies, geometry, and resin filler in the core tip on stress distribution of sandwich endings with tapering angles from 20° to 45°. The analytical approach demonstrated that core normal stress decreased effectively with increase of upper radius on the top facesheet.…”