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.

Application of different imaging techniques for the characterization of damage in fiber reinforced polymer

“…Since the application of FRPs is in constant growth, extensive research has focused on identifying damage mechanisms that induce failure of engineering components. DIC has been increasingly utilized to obtain strain fields, and conduct detailed investigations of meso-and macromechanical aspects associated with FRP damage and failure [14,15,16,17]. Even though such measurements efficiently detect areas of strain localization corresponding to meso-and/or macro damage locations, the influence of bulk microstructural changes on the macroscopic response was not assessed.…”

Damage mode and load distribution of countersunk bolted composite joints

“…To accurately view surface strain fields and overcome the divergence issues of laminates, novel experimental and modeling methods have been proposed, such as using digital image correlation (DIC) measurement by Zhai et al, 17 Haris et al, 18 Hu et al 19 and explicit models by Liu et al, 20 Hu et al. 21 Classical progressive damage models by Yang et al, 22 Chowdhury et al, 23 Ge et al 24 were proved to be accurate for capturing the bolt load change or material damage propagation procedure for cracked laminates.…”

Thermal phenomenon of glass fibre composite under tensile static and fatigue loading

“…The benefit of infrared thermography in composite field is the viscosity of the matrix which is heated more than the metal. It helps find the first microscopic damage early and identify more individual degradation mechanisms, transverse cracks, interface cracks, fibre cracks, etc [22,31,32]. Fibrous composites are considered as very successful targets for the application of thermography due to their thermal and emissive properties [33].…”