Stiffened composite constructions are increasingly being used in the primary structures of aircraft. One key component in these structures is the assembly between the skin and the stringer. The purpose of the stringers sandwiched between two separate layers of skin is to provide structural integrity to a relatively weak skin-structure. Current practice is to fabricate the skin and the stringer separately, assemble them with adhesively bonded joints, and then co-cure the entire assembly in an autoclave. However, the reliability of the joint manufactured in this fashion is not dependable and hence requires riveting of the skin with the stringer by hundreds of mechanical fasteners. Although the mechanical fastener improves the joint reliability, it certainly increases the weight and reduces the strength of the structure by introducing stress concentration points around the rivet holes. In order to eliminate these disadvantages, an innovative low cost manufacturing technique has been developed. The technique utilizes the vacuum assisted resin transfer molding (VARTM) process to co-inject both the skin and the stringer in one integral step. Furthermore, the skin and the stringer are now part of one continuous fabric preform which by default eliminates any adhesive bonding. Several skin-stringer assemblies with plain weave carbon fabric and SC-15 epoxy resin have been manufactured following this procedure. Stability of the manufactured skin-stringer assembly has been investigated experimentally. The extensive analysis focused on the determination of the critical load corresponding to the instability of the structure, failure load and study of the failure mechanisms. Details of manufacturing procedures and experimental investigations are presented in the paper.
Integral manufacturing of composite skin-stringer assembly and their stability analyses
Applied Composite Materials ; 11 , 3 ; 155-171
2004
17 Seiten, 14 Quellen
Article (Journal)
English
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