Crushing behaviour of glass fibre/epoxy composite pipes: the effects of winding angles, ageing, and temperatures

Abstract

The effects of hydrothermal ageing on the crushing behaviour of glass fibre-reinforced epoxy (GRE) pipes are discussed. Pipes with three different winding angles (±45°, ±55°, ±63°) were manufactured using the filament winding process. Prior to the compression tests, the pipes were hydrothermally aged in tap water at a constant temperature of 80°C for periods of 500, 1000, and 1500 hours. Uniaxial compressive tests were conducted on the virgin and aged samples using a universal testing machine (UTM, Shimadzu) in accordance with ASTM D695-10. The tests were also performed at temperatures ranging from room temperature (RT) to 45°C, 65°C, and 95°C to study the response of the pipes at elevated temperatures. The temperatures were selected based on the results of differential scanning calorimetry (DSC) tests, where the value of the glass transition temperature (Tg) was determined to be 66.39°C. Scanning electron microscopy (SEM) images were captured and the relationship between the ageing period and strength of the GRE pipes was determined. The results indicate that the strength of the GRE pipes significantly decreases with increase in the temperature where pipes compressed at RT produced the highest strength while the lowest is at 95°C. The same could be observed for ageing periods where virgin pipes shows the highest compressive strength and the strength degrades as the ageing period was extended. The strength of GRE pipes increases as the winding angles decrease. ±45° winding angle has the highest strength followed by ±55°, and lastly ±63°. The experimental results were also compared with theoretical analysis obtained from Berbinau’s based model and the experimental values are found to correlate well with the predicted values.