Lifetime prediction for ABS pipes subjected to combined pressure and deflection loading

Abstract

As part of an investigation into the performance of acrylonitrile-butadiene-styrene (ABS) systems for water transportation, this paper presents a method for predicting the service lifetimes of buried pipes under in-service loading conditions. A linear fracture mechanics approach was used to analyze brittle failure initiating from adventitious flaws located at the bore surface of pipe. Failure criteria were determined using the time-dependent, quasistatic, plane strain fracture toughness of the ABS material, combined with empirical parameters that describe slow, steady crack growth. The expected operating conditions of a buried pipe were then separated into static loading contributions from internal pressure, diametrical deflection and residual stress. Idealized stress intensity factors associated with mode-I crack opening under each of these components were determined using a finite element analysis and superposed to describe the general case in service. The computed nett stress intensity factor was then combined with the previously determined fracture toughness and slow crack growth data in an algorithm to simulate incremental radial crack growth from the pipe bore. Predicted failure times compared well with an experimental model of expected operating conditions, which combined hydrostatic pressure and parallel-plate deflection loading of an internally notched pipe. The prediction method was also used to identify the factors that control the lifetime of a pipe in service. The influence of material visco-elasticity was investigated by simulating variations in fracture toughness and slow crack growth resistance. It was proposed that, in practice, these variations are governed by opposing changes in visco-elasticity. The effect of changing diametrical deflection and residual stress distribution were also simulated, allowing recommendations on pipe manufacture and installation conditions to be made.

Lifetime Assessment of Load‐Bearing Polymer Glasses: The Influence of Physical Ageing

“…The hairline crack is a slit in axial direction with a small plastic zone at the ends. Various models exist that can predict the failure kinetics in regime II quantitatively, most of which are based on a fracture mechanics approach to calculate the crack growth rate (e.g 5, 10, 11…”

State-of-the-art review of water pipe failure prediction models and applicability to large-diameter mains

“…Brittle failure of the pipes is calculated using the applied stress intensity factor applied to the pipe, based on a finite element analysis by Lu et al (2003). Which type of failure is critical depends on which failure stress is lower, the net section yield stress or the stress required for brittle failure.…”

Direct comparison of the compliance method with optical tracking of fatigue crack propagation in polymers

“…and/or handling (scratches), and the crack propagation rate, which strongly depends on loading and environmental conditions. [2][3][4][5] To evaluate the crack propagation kinetics experimentally, a variety of methods can be used to monitor the crack length in time; some are specific to the type of material.…”

“…In contrast, the characterisation of (fatigue) crack propagation rates has been forced towards significantly longer testing times due to increasing resistance to crack propagation of currently available M A N U S C R I P T A C C E P T E D ACCEPTED MANUSCRIPT 5 materials. [3,34] The time-scale of an experiment is, therefore, now directly related to the crack propagation rate, which is known to be influenced by test conditions [2,4,5] such as the magnitude of the load applied, the load amplitude, the frequency and the temperature, but also at specimen level by details such as the initial crack size. Due to the non-linearity and time dependency of polymers, the question rises whether a method such as the compliance method is actually applicable in these cases.…”