CFRP/titanium hybrid material for improving composite bolted joints

The structural joining remains an essential challenge for the development of composite aerospace structures: every structural interconnection means a disturbance of an optimized structure resulting in an increase in overall structural weight. The lightweight potential of advanced, high-performance fiber composite materials is affected more strongly by mechanical fastening techniques than by conventional metallic materials due to the low shear and bearing capabilities of CFRP materials. Local embedding of thin titanium layers into the composite laminate in the coupling region results in a considerable improvement in structural efficiency of bolted and riveted joints in CFRP structures. This improvement is not only obvious in the increase in shear and bearing capabilities, but also in the resulting possibilities for a design no longer burdenend by local material thickening, excentricities and additionally excited local bending stresses. This report displays experimental results demonstrating the advantageous influence of titanium hybridization on specific characteristics of CFRP-materials, thus proving the mechanical potential of CFRP/titanium hybrid materials when used as an advanced reinforcement technique for highly loaded composite joints. (C) 2007 Elsevier Ltd. All rights reserved.