Experimental analysis of composite bolted joints using digital image correlation

Abstract

In this work, the application of the digital image correlation (DIC) technique to experimentally study progressive damage of single-lap composite bolted joints is explored. This technique is also used to provide surface strain fields and to analyse outof-plane phenomena of the joints due to the effect of laminate pattern, laminate thickness, fastener size, fastener type and bushing. The specimens were manufactured from plain weave carbon/epoxy composites. The bearing test was conducted in accordance with ASTM D5961/D5961M-13. The digital image correlation was performed using the commercial Vic-3D digital image correlation system. It was found that strain concentrations observed in the specimens can be used to identify full-field damage onset and to monitor damage progression during loading. Moreover, there is interaction between laminate pattern, laminate thickness, fastener size, fastener type and bushing on bearing strengths (ultimate and 2% offset bearing strengths), surface strain concentrations and out-of-plane displacement. The DIC results can potentially be used to develop and accurately validate numerical models.

Keywords

• carbon/epoxy composite
• bolted joint
• bearing strength
• digital image correlation
• progressive damage