Guidelines for selecting the dimensions of adhesively bonded end-loaded split joints: An approach based on numerical cohesive zone length

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%.

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Numerical evaluation of crack stopping mechanisms in composite bonded joints due to corrugation and bolts

MATEC Web of Conferences ◽

10.1051/matecconf/201930401003 ◽

2019 ◽

Vol 304 ◽

pp. 01003 ◽

Cited By ~ 1

Author(s):

Konstantinos Tserpes

Keyword(s):

Crack Growth ◽

Cohesive Zone ◽

Cohesive Zone Modeling ◽

Bonded Joints ◽

Adhesively Bonded ◽

Static Loads ◽

Lap Shear ◽

Crack Growth Simulation ◽

Zone Modeling ◽

Fatigue Loads

In this paper, the crack stopping mechanisms in corrugated composite bonded joints and hybrid bonded/bolted joints were evaluated numerically using the cohesive zone modeling approach. For the study, the DCB (double-cantilever beam) and the CLS (crack-lap shear) specimens were modelled. The first two specimens were subjected to static loads and the latter both to static and fatigue loads. The analysis was performed using the LS-DYNA explicit FE code. Fatigue crack growth simulation was performed using an in-house developed user-defined subroutine (UMAT). The numerical results reveal a crack stopping in the corrugated DCB, no crack stopping in the corrugated CLS and a reduction of crack growth rate in the bonded/bolted CLS for both static and fatigue loads. The methods and the findings of the present study can be used for the design of crack stopping features in adhesively bonded primary composite aircraft structures.

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Investigating Some Technical Issues on Cohesive Zone Modeling of Fracture

Journal of Engineering Materials and Technology ◽

10.1115/1.4007605 ◽

2012 ◽

Vol 135 (1) ◽

Cited By ~ 13

Author(s):

John T. Wang

Keyword(s):

Cohesive Zone ◽

Process Zone ◽

Cohesive Zone Modeling ◽

Small Scale ◽

Zone Length ◽

Cohesive Model ◽

Cohesive Models ◽

Cohesive Laws ◽

Technical Issues ◽

Linear Softening

This study investigates some technical issues related to the use of cohesive zone models (CZMs) in modeling the fracture of materials with negligible plasticity outside the fracture process zone. These issues include: (1) why cohesive laws of different shapes can produce similar fracture predictions, (2) under what conditions CZM predictions have a high degree of agreement with linear elastic fracture mechanics (LEFM) analysis results, (3) when the shape of cohesive laws becomes important in the fracture predictions, and (4) why the opening profile along the cohesive zone length (CZL) needs to be accurately predicted. Two cohesive models were used in this study to address these technical issues. They are the linear softening cohesive model and the Dugdale perfectly plastic cohesive model. Each cohesive model uses five cohesive laws of different maximum tractions. All cohesive laws have the same cohesive work rate (CWR) defined by the area under the traction–separation curve. The effects of the maximum traction on the cohesive zone length and the critical remote applied stress are investigated for both models. The following conclusions from this study may provide some guidelines for the prediction of fracture using CZM. For a CZM to predict a fracture load similar to that obtained by an LEFM analysis, the cohesive zone length needs to be much smaller than the crack length, which reflects the small-scale yielding condition requirement for LEFM analysis to be valid. For large-scale cohesive zone cases, the predicted critical remote applied stresses depend on the shape of the cohesive models used and can significantly deviate from LEFM results. Furthermore, this study also reveals the importance of accurately predicting the cohesive zone profile for determining the critical remote applied load.

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Analysis of the cohesive zone and crack length correction in the adhesively bonded double cantilever beam specimen

The Journal of Adhesion ◽

10.1080/00218464.2016.1219256 ◽

2016 ◽

Vol 93 (14) ◽

pp. 1146-1161 ◽

Cited By ~ 1

Author(s):

A. B. de Morais

Keyword(s):

Crack Length ◽

Cantilever Beam ◽

Cohesive Zone ◽

Double Cantilever Beam ◽

Beam Specimen ◽

Adhesively Bonded ◽

Double Cantilever Beam Specimen

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Static and Fatigue Failures of Adhesively Bonded Laminate Joints in Moist Environments

International Journal of Damage Mechanics ◽

10.1177/1056789510395363 ◽

2011 ◽

Vol 20 (8) ◽

pp. 1217-1242 ◽

Cited By ~ 31

Author(s):

K. B. Katnam ◽

A. D. Crocombe ◽

H. Sugiman ◽

H. Khoramishad ◽

I. A. Ashcroft

Keyword(s):

Cohesive Zone ◽

Experimental Tests ◽

Static Fatigue ◽

Test Results ◽

Adhesively Bonded ◽

Aerospace Applications ◽

Numerical Predictions ◽

Fatigue Failures ◽

Good Agreement

Advanced structural adhesives are now an important joining technique in automobile and aerospace applications. The perceived uncertainty in the long-term structural performance of bonded members when subjected to static/fatigue loads in aggressive environments is probably restricting an even more widespread use of this joining technology. In this article, the effect of moisture on the static and fatigue resistances of adhesively bonded laminate joints was investigated. Experimental tests were performed on both aged and unaged adhesively bonded laminate joints for static and fatigue responses. Further, using a cohesive zone approach for the adhesive bondlines, a combined diffusion–stress analysis was developed to predict the progressive damage observed in the joints tested experimentally. The numerical predictions were found to be in good agreement with the experimental test results.

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