On the prediction of long‐term creep‐failure of GRP pipes in aqueous environment

Abstract

The aim of this work was to study the long‐term failure of GRP (Glass fiber‐reinforced Polymer) pipes under the influence of moisture absorption. These pipes are used in water transportation, which has an important effect on the mechanical properties of the polymeric matrix. The GRP pipes are usually tested under ring deflection or internal pressure conditions. This study presents and analyzes experimental creep‐rupture data obtained from standard test methods under ring deflection conditions. This loading configuration simulates in laboratory the conditions verified in a subsoil installation. The creep testing was carried out under constant dead weight on unconditioned and preconditioned samples in a submerged condition. The diametrical deflection of samples was measured periodically, and the time to failure of each sample was recorded. The main purpose of this work was to determine the short and long‐term rupture energies of GRP pipes and assess the influence of moisture preconditioning on those values. The observed failure mode was always the same. It was concluded that the energy at failure decreases with time. The influence of the preconditioning on the creep‐rupture of GRP pipes was considered negligible. Different time‐dependent failure models were described and used for long‐term extrapolation of the experimental data. The maximum strain at failure decreased about 12% from 0.1 to 1,000 hr of creep testing. Furthermore, data extrapolation to 50 years predicts a reduction of strength of about 60%, founded on the most conservative time‐dependent failure criterion. POLYM. COMPOS., 2010. © 2009 Society of Plastics Engineers

Creep and Dynamic Mechanical Analysis Studies of Peroxide‐Crosslinked Ethylene‐Octene Copolymer

“…Creep is the time‐dependent behavior of the material under stress and reveals the usability of a polymer in long term application. Many researchers have shown their interest in creep behavior due to its practical importance in the applications for water/oil tanks, glass‐fiber‐reinforced polymer (GRP) pipes,1 extruded composite profiles2 and bottles/containers 3. High temperature creep test is being used in foam industry, where the polyolefin foam is used, e.g., for camping mats.…”

Application of continuum damage mechanics model in terms of fatigue life assessment for low cycle and quasi static loadings

“…This approach does not require identification of fatigue cycles and the method itself is a cumulative one. Secondly, this approach is universal as it can be used in many different areas of materials fatigue including: monotonic loading static loading causing material creep, and cyclic loads resulting in a material fatigue [5][6][7][8]. As far as the fatigue itself is concerned, this approach is used in two areas of fatigue: In low-fatigue and in high cycle fatigue [8,12].…”

Estimation of creep strain and creep failure of a glass reinforced plastic by semi-analytical methods and 3D numerical simulations

“…Glass reinforced plastic pipes may feature a complex structure, including chopped strand mat layers on the inner side and filament wound layers on the outer side [9,10,11]. Short-time hydraulic failure occurs on the inner diameter [10].…”

“…Short-time hydraulic failure occurs on the inner diameter [10]. Ring deflection tests may be performed according to standard ISO 9967 to estimate the time-dependent strain of a pipe and study the long term creep failure [12,9]. In this case, failure mode was always the same, fiber breakage, and always localized in the same region, on the inner diameter [9].…”