Strength of adhesively bonded single-lap and lap-shear joints

For lightweight materials, e.g. aluminium, the definition of proper joining technology relies on material properties, as well as design and manufacturing aspects. Substrate thickness is especially relevant due to its impact on the weight of components. The present work compares the performance of adhesively bonded (AJ) to hybrid riveted-bonded joints (HJ) using aluminium substrates. To assess the lightweight potential of these joining methods, the effect of substrate thickness (2 and 3 mm) on the lap-shear strength (LSS) of single lap joints is investigated. An epoxy-based structural adhesive is employed for bonding, whilst HJs are produced by lockbolt rivet insertion into fully cured adhesive joints. The stiffness of joints increased with an increase of substrate thickness. HJs presented two-staged failure process with an increase in energy absorption and displacement at break. For HJs, the substrate thickness changed the failure mechanism of rivets: with thicker substrates failure occurred due to shear, whereas in thinner substrates due to rivet pulling-through. The LSS of 2 mm and 3 mm-thick AJs is similar. With 2 mm-thick substrates, the LSS of HJs was lower than AJs. In contrast, the highest LSS is obtained by the 3 mm-thick HJs. The highest lightweight potential, i.e. LSS divided by weight, is achieved by the 2 mm-thick AJs, followed by the 3 mm-thick HJs with a loss of ca. 10% of specific LSS.

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Impact of manufacturing imperfections and surface defects on stress–strain behaviour of flexible adhesive joints

Proceedings of the Institution of Mechanical Engineers Part E Journal of Process Mechanical Engineering ◽

10.1177/0954408920927634 ◽

2020 ◽

Vol 234 (5) ◽

pp. 499-510

Author(s):

P Liška ◽

B Nečasová ◽

J Šlanhof ◽

P Schmid ◽

V Motyčka

Keyword(s):

Joint Strength ◽

Surface Defects ◽

Negative Impact ◽

Deformation Behaviour ◽

Adhesively Bonded ◽

Adhesion Promoter ◽

Premature Failure ◽

Lap Shear ◽

Manufacturing Techniques ◽

Adhesively Bonded Joint

Precise adherence to the manufacturer’s instructions and requirements plays an important role in various installation processes. The presented paper deals with the evaluation of the effect of manufacturing imperfections and surface defects on the failure behaviour of flexible adhesive intended for façade application. The failure to comply with the accepted procedures is more common in construction practice than in other sectors of the industry, mostly due to the surrounding conditions and lack of trained supervision. Unfortunately, this may lead to premature failure of adhesively bonded joints and a considerable shortening of the service life of the entire construction. To determine the potential of the risk, five types of artificially applied (a) manufacturing imperfections: (1) application on wet adhesion promoter, (2) application after the expiry of the laying-time, (3) curing of samples at +1℃ (b) surface defects: (4) application on a wet substrate and (5) application on a dirty surface, were suggested. Moreover, the Taguchi L32 orthogonal array design was used to arrange the test setup of all possible combinations. The 1 K polyurethane adhesive was applied in tensile butt joints and single-lap shear joints composed of aluminium alloy and thermally modified wood substrates. The obtained results confirmed that non-observance of the required manufacturing techniques and recommended procedures can have a negative impact on the decrease of the adhesively bonded joint strength and deformation behaviour. Surprisingly, the most critical was not the combination of all suggested types of imperfections and defects. The performed one-way ANOVA revealed that the most perilous was the combination of types 2 and 4 in the tensile test with 77% joint strength reduction. In the shear test, the most critical was the combination of all types of imperfection and defects which led also to a 77% drop of shear strength.

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A Numerical and Experimental Study of Adhesively-Bonded Polyethylene Pipelines

Polymers ◽

10.3390/polym11091531 ◽

2019 ◽

Vol 11 (9) ◽

pp. 1531 ◽

Cited By ~ 3

Author(s):

Guilpin ◽

Franciere ◽

Barton ◽

Blacklock ◽

Birkett

Keyword(s):

Cohesive Zone ◽

Adhesive Bonding ◽

Structural Integrity ◽

Cohesive Zone Model ◽

Low Cost ◽

Element Model ◽

Zone Model ◽

Adhesively Bonded ◽

Lap Shear ◽

Lap Shear Test

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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Test Method for Determining Strength of Adhesively Bonded Rigid Plastic Lap-Shear Joints in Shear by Tension Loading

10.1520/d3163-96 ◽

1996 ◽

Author(s):

Keyword(s):

Test Method ◽

Adhesively Bonded ◽

Rigid Plastic ◽

Lap Shear ◽

Tension Loading

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Test Method for Determining Strength of Adhesively Bonded Rigid Plastic Lap-Shear Joints in Shear by Tension Loading

10.1520/d3163-01 ◽

2001 ◽

Author(s):

Keyword(s):

Test Method ◽

Adhesively Bonded ◽

Rigid Plastic ◽

Lap Shear ◽

Tension Loading

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Strategies for the Analysis of the Behavior of an Adhesive in Bonded Assemblies

Journal of Engineering Materials and Technology ◽

10.1115/1.4004049 ◽

2011 ◽

Vol 133 (3) ◽

Author(s):

Jean Yves Cognard ◽

Romain Créac’hcadec ◽

Laurent Sohier

Keyword(s):

Experimental Data ◽

Edge Effects ◽

Nonlinear Behavior ◽

Bonded Joints ◽

Stress Singularities ◽

Tensile Shear ◽

Adhesively Bonded ◽

Shear Tests ◽

Lap Shear ◽

Initiation And Propagation

Experimental and numerical analyses of the mechanical behavior of bonded joints can be made particularly difficult by the influence of edge effects. Therefore, understanding the stress distribution in an adhesive joint can lead to improvements in adhesively-bonded assemblies. Such an analysis is proposed in the case of usual single lap shear specimens. Stress singularities can contribute to the initiation and propagation of cracks in the adhesive. Thus, in order to obtain reliable experimental data to analyze the nonlinear behavior of an adhesive in an assembly, tests which strongly limit the influence of stress singularities must be proposed. The design and the abilities of such a device for shear tests are presented. Moreover, some experimental results obtained using a modified Arcan fixture, which has been designed to strongly limit edge effects, are presented in the case of monotonic and complex history loadings. Furthermore, a 2D non associated elasto-visco-plastic model is proposed to accurately describe the experimental behavior under tensile-shear monotonic loadings. An extension of this model is also proposed to represent relaxation type effects under shear loadings.

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