Effect of seawater immersion on the drill induced delamination failure in glass fiber reinforced polymer composites – Experimental and statistical analysis.

• Marine glass fiber reinforced composites are drilled. • The effects of seawater treatment on the increase in drill-induced delamination failure are investigated. • Different material thicknesses (6, 8, and 10 mm) and immersion times (20, 40, and 60 days) were examined. • The significance of spindle speed as an input deciding parameter is emphasized. • The increase in peel up delamination failure seen after 60 days of seawater immersion was 290.22, 305.86 and 250.81 %. • The increase in the push down delamination failure seen after 60 days of seawater immersion was 69.48, 76.38 and 64.28 % in 6, 8 and 10 mm composites. Composite materials, particularly glass fiber reinforced polymer (GFRP) composite, have established a strong presence in the marine industry. Its marine applications range from constructing massive naval vessels to constructing simple fishing boat hulls. Previous research has established that seawater aging has a detrimental effect on the physical and mechanical properties of GFRPs. Additionally, drilling composites are known to cause delamination damage, resulting in a high failure rate. Since composite components are assembled with fasteners, drilling operations are unavoidable. Thus, the current study examines the effect of seawater aging at a macroscopic level while considering the input parameters spindle speed and feed and material thickness and the response variables as peel-up and push-down delamination damages. The result indicated higher failure rates in the seawater-treated composites than in untreated composites. The maximum damages were seen in the 60 days of immersed composites, wherein the peel-up delamination damage increased by 290.22, 305.86, and 250.81 %, and the push-down delamination damage increased by 69.48, 76.38, 64.28 % in 6, 8 and 10 mm composites, respectively. The combinational effect of seawater degradation of GFRP composites and the damages caused by the cutting forces (function of speed and feed) attribute to the failure rate increase concerning the drilling-induced delamination damages in the composites. In addition to investigating the effect of seawater immersion on damages, the study also provides the regression analysis-based mathematical model having high goodness of fit and predicting capability to determine the damages for the given values of input variables. [ABSTRACT FROM AUTHOR]