Influence of Specimen Tabs on the Compressive Strength of a Unidirectional Composite Material

(Kecei\cJ J a n u q 16. 1990) (Rmircd hlay 22. 1990) ABSHACT: An experimental study itas performed to determine the cfTect of type of tabbing material and tab taper on the measured axial compressive strength of 3 unidiree-tional carbonkpoxy material. Two types of tabbing mterials (hot-rolled. low carbon steel and glass-fabridepoxy) and two tab taper geometries (untapered and 30 " taper) were uti-lized. Addi~iomlly. the influence of partial tab debonding on the nieasured compressive strength Has determined. A standard IITRl compression test fixture U';IS used. Tapered steel tabs provided consistently higher compressive strengths than tapered glass-fabric/ epoxy tabs, o r untapered steel or glass-fabridepoxy tabs. Deliberately introducing regions of tab debonding in untapered glass-fabriclepoxy tabtcd specimens resulted in only a small decrease in compressive strength. IhTRODUCTION HE PRlhlARY OBJECXIVE of the present study was to determine thc influence T of the type of tabbing material, and tab taper, on the axial compressive strength of a highly orthotropic, high axial strength, high axial stiffness, unidirec-tional composite material. This type of composite material is pcrhaps the most dificult to test in cornpression successfully. Thus, if reliable methods can bc dc-veloped to test this material, it should bc possible to test most other types of com-posite materials in a similar manner with reasonable confidence A Hercules AS4/3501-6 carbonlepoxy unidirectional composite \vas utilized [I]. While there arc other carbon fibers available that have higher moduli, thus resulting in even more highly orthotropic unidirectional composites [ 2] , the Hcr-cules AS4 carbon fibcr \\as selected here as being widely used, and resulting in 'Professor ol hlechnical Enginccring. **Ph.D. gradus~e siudcnr