AGEING EFFECTS ON BURST PRESSURE TEST OF IMPACTED GLASS FIBRE REINFORCEMENT EPOXY (GRE) PIPES Hawa A.1,a, M. S. Abdul Majid1,b, M. Afendi1,c, Haslan M.2,d, Pranesh Krishnan1,e, A. M. Amin1,f 1School

of Mechatronic Engineering, Universiti Malaysia Perlis (UniMAP), 02600 Arau, Perlis, Malaysia. 2Advanced

Material Research Centre (AMREC), SIRIM Berhad, 09000 Kulim, Kedah, Malaysia.

ABSTRACT • The main objective of this experimental study is to investigate the effects of hydrothermal ageing on the pressure bearing capacity of the Eglass/epoxy composite pipes subjected to impact loadings. • The pipes were produced by the conventional filament winding technique comprises of six antisymmetric layers with (±55°)3 winding angles. The pipes were immersed in tab water for period of 500, 1000, and 1500 hours. The specimens were impacted at three different energy levels; 5 J, 7.5 J, and 10 J using an instrumented drop weight impact testing machine (IMATEK IM10). The samples were then subjected to pressure test until distinct leakage failure is observed. • The results indicates that peak force and contact time increase with increasing impact energy. The tests results show that the burst pressure decreases with increase in energy levels during impact loading. During the burst tests, several damage types named leakage and eruption were observed.

INTRODUCTION • Composite pipes are extensively used for underwater and underground transportation of fluid materials such as natural gas, oil, thermal water, waste water, and even drinking water, due to their high corrosion, good heat resistance, and high strength properties. The burst failure pressure of glass fibre reinforced composite pipes is an important performance indicator because that they will subjected to various loading during service life. These loads may cause the potential damaged zones in the filament wound composite pipes which are often went undetected by visual inspection.

EXPERIMENTAL DETAILS Specimen preparation

• GRE pipes were manufactured using a CNC controlled filament winding machine. • Six antisymmetric layers. • Reinforcement - E-glass fibre with roving 1200 Tex/17µm diameter. • Matrix - D.E.R. 331 epoxy resin. • Post cure - 160 °C for 2 hours in the oven.

SPECIMEN Length : 500 mm Thickness : ±2.4mm O. Diameter: ±104.8 mm I. Diameter : ±100 mm Winding angle : ±55°

EXPERIMENTAL DETAILS Specimen preparation

Ageing Condition

Ageing

Time (hours)

Room temp.

Virgin = 0 hour

80°C

500 hours

• Ageing medium – tap water

= 21 days

1000 hours = 42 days 1500 hours = 63 days Schematic diagram ageing enclosure

EXPERIMENTAL DETAILS

Specimen preparation

Ageing Condition

Drop weight impact test

Impactor - Hemispherical (d = 12.7 mm) Impact Energy Level - 5, 7.5, 10 J ASTM Standard - D2444

Drop weight impact test machine with high speed camera

EXPERIMENTAL DETAILS Specimen preparation

Ageing Condition

Drop weight impact test

Burst test

• Tab water was used as the pressurized medium • Impacted pipe was filled with water with closed end setup. • It was slowly pressurised until the test specimen completely burst

Pressure test rig used for burst test Burst failure - eruption

RESULTS AND DISCUSSION • The pipes was carried out for three various impact energy levels at 5J, 7.5J and 10J. • Rebounding type curve was observed.

(a)

• The impact loading does not result in a serious damage to the specimen.

(b)

Force-displacement curves of GRE pipes (a) 5 J, (b) 7.5 J, and (c) 10 J impact energy

• Peak force and maximum displacement increase with increasing impact energy. (c)

RESULTS AND DISCUSSION • The 5J impacted samples offers the higher burst pressure compare to 7.5J and 10J energy levels. • It is because of decreasing of the mechanical strength in higher ageing time. • Damage - leakage occurred at low energy level and eruption occurred at higher energy level. • Burst strength of the pipes decreases by increasing of impact loading on GRE pipes.

Axial stress-ageing time diagram of impacted GRE pipes

CONCLUSION From the results obtained the following conclusions can be drawn: • Peak force and maximum deflection increase with increasing impact energy. Ageing time does not have significant effect on stiffness in impact loading while water ageing affect significantly on maximum displacement behaviour of composite pipe. Hence, the area of damage also will be larger. • The maximum burst pressure was observed to decline by increasing of impact energy level. This is because delamination damage caused by high impact energy level has accelerated the burst process. • Water ageing and impact loading have essential effect on burst failure pressure of the composite pipes.

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2.

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