Mechanical characterisation of CFRP-steel hybrid composites

Hybrid CFRP-steel composites are a very promising solution to increase bolt bearing strength in composite aerospace structures. This paper reports the findings on the static and fatigue tests performed in composite specimens made of CFRP and steel foils and compares these results with conventional CFRP specimens. A servo-hydraulic machine was used to perform fatigue tests under load control regime with R = 0.1. Sinusoidal waveforms were adopted to control the load time evolution. Hybrid specimens have a considerable higher static strength than conventional CFRP and therefore their stress levels are higher in absolute values than conventional CFRP specimens. Manufacturing and quality control issues are also addressed. Conventional manufacturing techniques and current quality control techniques can be successfully applied to hybrid CFRP-steel composites.