A Numerical and Experimental Study of Adhesively-Bonded Polyethylene Pipelines.

Guilpin Guilpin,Barton Barton,Franciere Franciere,Birkett Birkett,Blacklock Blacklock

doi:10.3390/polym11091531

Guilpin Guilpin, Barton Barton + Show 3 more

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https://doi.org/10.3390/polym11091531

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Abstract

Adhesive bonding of polyethylene gas pipelines is receiving increasing attention as a replacement for traditional electrofusion welding due to its potential to produce rapid and low-cost joints with structural integrity and pressure tight sealing. In this paper a mode-dependent cohesive zone model for the simulation of adhesively bonded medium density polyethylene (MDPE) pipeline joints is directly determined by following three consecutive steps. Firstly, the bulk stress-strain response of the MDPE adherend was obtained via tensile testing to provide a multi-linear numerical approximation to simulate the plastic deformation of the material. Secondly, the mechanical responses of double cantilever beam and end-notched flexure test specimens were utilised for the direct extraction of the energy release rate and cohesive strength of the adhesive in failure mode I and II. Finally, these material properties were used as inputs to develop a finite element model using a cohesive zone model with triangular shape traction separation law. The developed model was successfully validated against experimental tensile lap-shear test results and was able to accurately predict the strength of adhesively-bonded MPDE pipeline joints with a maximum variation of <3%.

Highlights

Due to its unique combination of properties, polyethylene (PE) is the material of choice for low-pressure water and gas pipeline systems [1]
These material properties were used as inputs to develop a finite element model using a cohesive zone model with triangular shape traction separation law
The bulk stress-strain ( – ) response of the medium density polyethylene (MDPE) adherends obtained via tensile testing of five specimens is presented in (σ–ε)

Summary

Introduction

Due to its unique combination of properties, polyethylene (PE) is the material of choice for low-pressure water and gas pipeline systems [1]. Perhaps the most attractive feature of PE pipeline systems is the ability to rapidly fuse sections together to form joints with strength equivalent to the parent material This allows networks with a minimum design life of 50 years [7]. Fusion can be achieved using hot iron and electrofusion techniques to produce a range of joint geometries, such as butt welds, socket joints and saddle joints, as well as applying repair patches In theory, these techniques should offer a reliable joining solution, fusion welding is a complex process requiring skilled operatives and its success is highly reliant upon multiple process parameters such as fusion pressure, melt temperature, heat soak and dwell times, and pipe cleanliness, ovality and alignment [7]

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