Investigation of the mechanical performance of hybrid bolted-bonded joints subjected to different ageing conditions: Effect of geometrical parameters and bolt size

Abstract

The hybrid bolted-bonded joining method is one of the most common joining approaches found in the marine industry, where it mitigates the concerns raised by the poor environmental resistance of adhesive joints. To overcome this issue, hybrid bolted-bonded joints are designed so that the bolts bear the load in case of failure of the adhesive layer. Due to the large susceptibility of the adhesively bonded area to environmental effects, proper sealing between the bolt and substrates in hybrid joints must be provided to avoid moisture diffusion through the adhesive layer from the drilled holes. In the current study, the degradation of the single lap hybrid bolted-bonded joints exposed to the ageing condition has been experimentally investigated. To this aim, the hole diameter to width ratio (D/W) as well as the hole diameter to edge distance ratio (D/E) have both been investigated. Hybrid bolted-bonded joints, considering two different bolt configurations, were aged and experimentally tested. In addition, to study the effects of geometrical parameters and ageing, drilled bonded joints were exposed to distilled water and saltwater for different periods (18 and 36 days). The results were compared with those of the joints which were dried for two days. Furthermore, Fourier transform infrared spectroscopy (FTIR) analysis was performed to detect changes in the chemical structure of the adhesive after different exposure times to water. According to the obtained results, whilst increasing the size of the bolt led to higher ultimate load (over 132% by doubling the bolt size), joints with higher D/W and D/E ratios experienced more noticeable adhesive failure when they were exposed to ageing conditions.

Keywords

• Hybrid bolted-bonded joints
• Ageing
• Leakage
• Adhesive bonding
• Mechanical fastening