scholarly journals Numerical and Experimental Study of Tensile Strength of Single and Double-Strap Repairs

2012 ◽  
Vol 730-732 ◽  
pp. 1018-1023
Author(s):  
Arnaldo M.G. Pinto ◽  
Raul D.S.G. Campilho ◽  
Isabel R. Mendes ◽  
A.G. Magalhães ◽  
A.P.M. Baptista
Keyword(s):  
Adhesive Bonding ◽  
Failure Modes ◽  
Cohesive Zone Model ◽  
Fatigue Cracks ◽  
Adhesive Layer ◽  
Elastic Stiffness ◽  
Zone Model ◽  
Shear Stresses ◽  
Adhesively Bonded ◽  
Shear Modes

Adhesive bonding as a joining or repair method has a wide application in many industries. Repairs with bonded patches are often carried out to re-establish the stiffness at critical regions or spots of corrosion and/or fatigue cracks. Single and double-strap repairs (SS and DS, respectively) are a viable option for repairing. For the SS repairs, a patch is adhesively-bonded on one of the structure faces. SS repairs are easy to execute, but the load eccentricity leads to peel peak stresses at the overlap edges. DS repairs involve the use of two patches, one on each face of the structure. These are more efficient than SS repairs, due to the doubling of the bonding area and suppression of the transverse deflection of the adherends. Shear stresses also become more uniform as a result of smaller differential straining. The experimental and Finite Element (FE) study presented here for strength prediction and design optimization of bonded repairs includes SS and DS solutions with different values of overlap length (LO). The examined values ofLOinclude 10, 20 and 30 mm. The failure strengths of the SS and DS repairs were compared with FE results by using the Abaqus®FE software. A Cohesive Zone Model (CZM) with a triangular shape in pure tensile and shear modes, including the mixed-mode possibility for crack growth, was used to simulate fracture of the adhesive layer. A good agreement was found between the experiments and the FE simulations on the failure modes, elastic stiffness and strength of the repairs, showing the effectiveness and applicability of the proposed FE technique in predicting strength of bonded repairs. Furthermore, some optimization principles were proposed to repair structures with adhesively-bonded patches that will allow repair designers to effectively design bonded repairs.

scholarly journals A Numerical and Experimental Study of Adhesively-Bonded Polyethylene Pipelines

Polymers ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1531 ◽  
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%.

scholarly journals Predicting interlaminar damage behaviour of fibre-metal laminates containing adhesive joints under bending loads

2021 ◽  
pp. 073168442110517
Author(s):  
Ahmad SM Al-Azzawi ◽  
Luiz F Kawashita ◽  
Carol A Featherston
Keyword(s):  
Cohesive Zone ◽  
Failure Modes ◽  
Cohesive Zone Model ◽  
Adhesive Joints ◽  
Interfacial Shear ◽  
Zone Model ◽  
Shear Stresses ◽  
Bending Loads ◽  
Fibre Metal ◽  
Fibre Metal Laminate

This study includes experimental and numerical investigations on fibre-metal laminate structures containing adhesive joints under static bending loads. Experimental tests were carried out on Glare® 4B specimens manufactured in-house and containing doubler joint features. Numerical analyses were performed using Abaqus software including damage in the glass fibre reinforced polymer layers, ductile damage in the resin pockets (FM94 epoxy) and plasticity in the metal layers. A new cohesive zone model coupling friction and interfacial shear under through-thickness compressive stress has been developed to simulate delamination initiation and growth at the metal/fibre interfaces with the adhesive joint under flexural loading. This model is implemented through a user-defined VUMAT subroutine in the Abaqus/Explicit software and includes two main approaches, firstly, combining friction and interfacial shear stresses created in the interlaminar layers of the fibre-metal laminate as a result of through-thickness stresses and secondly, considering elastic-plastic damage behaviour using a new cohesive zone model based on the trapezoidal law (which provides more accurate results for the simulation of toughened epoxy matrices than the commonly used bilinear cohesive zone model). Numerical results have been validated against experimental data from 4-point bending tests and a good correlation observed with respect to both crack initiation and evolution. Delamination and shear failure were noted to be the predominant failure modes under bending stresses as expected. This is due to the higher mode-II stresses introduced during bending which cause different damage evolution behaviour to that seen for axial stresses. Finite element results revealed that both friction and shear strength parameters generated from through-thickness compression stresses have a significant effect in predicting damage in fibre-metal laminate structures under this type of loading.

scholarly journals Strength Prediction of Adhesively-Bonded Scarf Repairs in Composite Structures under Bending

2010 ◽  
Vol 636-637 ◽  
pp. 233-238 ◽  
Author(s):  
Raul D.S.G. Campilho ◽  
Marcelo F.S.F. de Moura ◽  
A.M.G. Pinto ◽  
Dimitra A. Ramantani ◽  
J.J.L. Morais ◽  
...  
Keyword(s):  
Composite Structures ◽  
Mixed Mode ◽  
Failure Modes ◽  
Numerical Study ◽  
Adhesive Layer ◽  
Elastic Stiffness ◽  
Cohesive Elements ◽  
Adhesively Bonded ◽  
Element Analysis ◽  
Cohesive Laws

This work reports on the experimental and numerical study of the bending behaviour of two-dimensional adhesively-bonded scarf repairs of carbon-epoxy laminates, bonded with the ductile adhesive Araldite 2015®. Scarf angles varying from 2 to 45º were tested. The experimental work performed was used to validate a numerical Finite Element analysis using ABAQUS® and a methodology developed by the authors to predict the strength of bonded assemblies. This methodology consists on replacing the adhesive layer by cohesive elements, including mixed-mode criteria to deal with the mixed-mode behaviour usually observed in structures. Trapezoidal laws in pure modes I and II were used to account for the ductility of the adhesive used. The cohesive laws in pure modes I and II were determined with Double Cantilever Beam and End-Notched Flexure tests, respectively, using an inverse method. Since in the experiments interlaminar and transverse intralaminar failures of the carbon-epoxy components also occurred in some regions, cohesive laws to simulate these failure modes were also obtained experimentally with a similar procedure. A good correlation with the experiments was found on the elastic stiffness, maximum load and failure mode of the repairs, showing that this methodology simulates accurately the mechanical behaviour of bonded assemblies.

Analysis of the performance of adhesively bonded corrugated core sandwich structures using cohesive zone method

2017 ◽  
Vol 22 (1) ◽  
pp. 104-124
Author(s):  
Ganiy Akhmet ◽  
Ye Yu ◽  
Ping Hu ◽  
Wen-bin Hou ◽  
Xiao Han
Keyword(s):  
Stress Distribution ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Sandwich Structures ◽  
Adhesive Layer ◽  
Geometrical Parameters ◽  
Zone Model ◽  
Adhesively Bonded ◽  
Joint Width ◽  
Panel Thickness

Stress analysis of adhesively bonded joints of sandwich structures is more complex. Only a few research works have studied this subject. The major obstacle is finding the stress distribution at the adhesive layer of sandwich structures under different loading conditions. This paper presents a study on stress distribution at the adhesive joints of the corrugated sandwich structure subjected to three-point bending using the cohesive zone model. Firstly, three cases of sandwich models with different types of glue on both longitudinal and transverse loading directions were calculated using cohesive zone model, and then the corresponding experiments were carried out and compared to prove the FEM results to validate the results through both load–displacement curves and failure deformation modes. Secondly, the cohesive zone model simulation was used to obtain the detailed stress distribution at the bonding joint with the effect of four major geometrical parameters: adhesive layer thickness, corrugated panel thickness, face panel thickness and adhesive joint width. Lastly, the results of stress analysis showed that the stress distribution is not uniform and is highly affected by the bonding joint's geometrical parameters, adhesive layer thickness and adhesive joint width.

scholarly journals Problem of Delamination in RC Beams Strengthened by FRP with Rheological Model of Adhesive Leyer

2016 ◽  
Vol 23 (4) ◽  
pp. 103-110 ◽  
Author(s):  
Krzysztof Kula ◽  
Tomasz Socha
Keyword(s):  
Finite Element ◽  
Rheological Model ◽  
Failure Modes ◽  
Cohesive Zone Model ◽  
Adhesive Layer ◽  
Epoxy Adhesive ◽  
Zone Model ◽  
Time Behavior ◽  
Long Time ◽  
Shell Finite Element

Abstract This paper deals with one of the most dangerous failure modes in layered structures, namely delamination. The strengthening layer is modelled by a solid-shell finite element. The mechanical modelling of delamination onset and propagation is based upon a cohesive zone model implemented into a cohesive element located between adhesive layer and a concrete structure. The long time behavior of epoxy adhesive layer is modelled with the five-parameter rheological model. The numerical simulations are accomplished within the commercial software package Abaqus by the implementation of a user-written finite element and user-written material.

scholarly journals Ultrasonic Deicing Efficiency Prediction and Validation for a Flat Deicing System

2020 ◽  
Vol 10 (19) ◽  
pp. 6640
Author(s):  
Zhonghua Shi ◽  
Zhenhang Kang ◽  
Qiang Xie ◽  
Yuan Tian ◽  
Yueqing Zhao ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Lead Zirconate ◽  
Efficiency Factor ◽  
Zone Model ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Total Energy Density ◽  
Average Shear

An effective deicing system is needed to be designed to conveniently remove ice from the surfaces of structures. In this paper, an ultrasonic deicing system for different configurations was estimated and verified based on finite element simulations. The research focused on deicing efficiency factor (DEF) discussions, prediction, and validations. Firstly, seven different configurations of Lead zirconate titanate (PZT) disk actuators with the same volume but different radius and thickness were adopted to conduct harmonic analysis. The effects of PZT shape on shear stresses and optimal frequencies were obtained. Simultaneously, the average shear stresses at the ice/substrate interface and total energy density needed for deicing were calculated. Then, a coefficient named deicing efficiency factor (DEF) was proposed to estimate deicing efficiency. Based on these results, the optimized configuration and deicing frequency are given. Furthermore, four different icing cases for the optimize configuration were studied to further verify the rationality of DEF. The effects of shear stress distributions on deicing efficiency were also analyzed. At same time, a cohesive zone model (CZM) was introduced to describe interface behavior of the plate and ice layer. Standard-explicit co-simulation was utilized to model the wave propagation and ice layer delamination process. Finally, the deicing experiments were carried out to validate the feasibility and correctness of the deicing system.

scholarly journals Compression Shear Properties of Adhesively Bonded Single-Lap Joints of C/C Composite Materials at High Temperatures

Symmetry ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1437 ◽  
Author(s):  
Yanfeng Zhang ◽  
Zhengong Zhou ◽  
Zhiyong Tan
Keyword(s):  
Composite Materials ◽  
Adhesive Layer ◽  
Lap Joints ◽  
Experimental Result ◽  
Shear Stresses ◽  
Test Results ◽  
Adhesively Bonded ◽  
Finite Element Software ◽  
Joint Structure ◽  
Simulation Results

The performance of joint structure is an important aspect of composite material design. In this study, we examined the compression shear bearing capacity of the adhesively bonded single-lap joint structure of high-temperature-resistant composite materials (C/C composite materials). The test pieces were produced in accordance with the appropriate ASTM C1292 standard, which were used for the compression shear test. The failure morphology of the layer was observed by a digital microscopic system and scanning electron microscope. The experimental result shows that the load on the test piece increased nonlinearly until the failure occurred, and most of the adhesive layer exhibited cohesive failures at three temperature points (400, 600, and 800 °C), while the interface failures occurred in a small part of the adhesive layer. A numerical analysis model was established using ABAQUS finite element software. The simulation results were compared with the test results to verify the correctness of the model. On the basis of correctness of the model verified by comparing the simulation results and the test results, the influences of temperature and overlapped length on the joint compression shear performance were studied through the validated simulation method. Numerical results showed that the ultimate load of the joint decreased with increases in temperature and that the distribution trends of the shear stresses in the overlapped length direction were substantially the same for joints of different overlapped lengths.

The Effect of Geometry and Material Properties on the Load Capacity of Single-Strapped Adhesive Bonded Joints

2008 ◽  
Vol 399 ◽  
pp. 89-96 ◽  
Author(s):  
Marin Sandu ◽  
Adriana Sandu ◽  
Dan Mihai Constantinescu ◽  
Ştefan Sorohan
Keyword(s):  
Adhesive Bonding ◽  
Load Capacity ◽  
Dissimilar Materials ◽  
Adhesive Layer ◽  
Adhesive Bond ◽  
Bonded Joints ◽  
Adhesively Bonded ◽  
Adhesive Bonded Joints ◽  
Major Factors ◽  
Selection Of

Adhesive bonding is a particularly effective method of assembling complex structures, especially those made from dissimilar materials. If the joint is well designed and correctly executed, the adhesive bond ought to be one of the strongest components of the structure and most certainly should not be the reason for reducing the load capacity or fatigue life. The major factors determining the integrity of an adhesive bond are selection of the most appropriate adhesive, joint design, preparation of the bonding surfaces, strict quality control in production and monitoring in service. This work focuses on the evaluation of the load capacity of some configurations of adhesively bonded single-strapped joints based on finite element analyses. The adhesive layer thickness, the overlap length, the adherent and strap thicknesses were varied as well as the materials properties.

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