Effects of impact fatigue on residual static strength of adhesively bonded joints

2021 ◽  
pp. 146442072199487
Author(s):  
S. Jalali ◽  
M.R. Ayatollahi ◽  
A. Akhavan-Safar ◽  
L.F.M. da Silva
Keyword(s):  
Energy Levels ◽  
Microscopic Analysis ◽  
Industrial Applications ◽  
Static Strength ◽  
Lap Joints ◽  
Impact Fatigue ◽  
Adhesively Bonded ◽  
Single Lap Joints ◽  
Cyclic Impact ◽  
The Impact

In most industrial applications, adhesive joints experience impact fatigue loads in service. The energy of each impact is too low to cause joint failure. Although the repetitive impacts usually do not apparently affect the joints, they can significantly reduce the strength of adhesively bonded structures. Accordingly, understanding the effect of impact fatigue on the residual strength of the bonded components is crucial in real applications. This study deals with this issue where the effect of impact fatigue on the residual static strength of single lap joints is analyzed. To achieve this, the manufactured single lap joints were categorized into four different groups. Group 1 joints were tested under static loading conditions. Joints in group 2 were tested under impact to obtain the impact strength of the single lap joints. To analyze the impact fatigue life of the joints, the single lap joints in group 3 were tested under cyclic impact at different energy levels until failure. To investigate the effect of impact fatigue on the residual static strength of the joints, single lap joints in group 4 were tested under a specific number of impact cycles followed by a static tensile test. Using microscopic analysis, the fracture surfaces of the tested specimens were analyzed. The results showed that cracks initiate from the middle of the bonded area as a result of cyclic impact stress waves. Then, by increasing the number of impacts, a large number of cracks nucleate from the edges of the joints and grow along the width to the middle of the overlap. A 3D finite element method was employed to analyze the stress distribution along the bondline under impact loads.

The impact of graphene nanoparticle additives on the strength of simple and hybrid adhesively bonded joints

2018 ◽  
Vol 53 (23) ◽  
pp. 3335-3346 ◽  
Author(s):  
Hamid Reza Borghei ◽  
Bashir Behjat ◽  
Mojtaba Yazdani
Keyword(s):  
Joint Strength ◽  
Tensile Tests ◽  
Lap Joints ◽  
Homogeneous Distribution ◽  
Adhesively Bonded ◽  
Adhesively Bonded Joints ◽  
Single Lap Joints ◽  
Hybrid Joints ◽  
Graphene Nanoparticles ◽  
The Impact

In this paper, the effect of graphene nanoparticle additive on the strength of simple and hybrid (rivet-bonded) single-lap joints is studied using the experimental method. Two different types of graphene with different number of layer and thicknesses are used in adhesive-graphene nanoparticle composite construction. At first, tensile tests are done on bulk specimens of adhesive with different additives. It is found that adding 0.5 wt% of graphene to the neat adhesive leads to an increase in the ultimate tensile strength of bulk specimens almost 24% and 12% for two graphene types compared to the neat adhesive. Also, the shear strength of adhesive and hybrid lap joints incorporating two types of graphene nanoparticles (types I and II) is compared to that of adhesive and hybrid joints without graphene nanoparticles. SEM results of fracture surfaces show that the inclusion of graphene nanoparticle to the adhesive increases the roughness of surfaces. Experimental results reveal that graphene nanoparticle increases the strength of bonded and hybrid joints. It is observed that, graphene with a lower thickness and number of layers has a better influence on joint strength. In fact, graphene nanoparticle type II makes a homogeneous distribution in adhesive-graphene nanoparticle composite and causes a significant increase on joint strength.

Predicting static strength in adhesively bonded single lap joints using a critical distance based method: Substrate thickness and overlap length effects

2016 ◽  
Vol 231 (1-2) ◽  
pp. 237-246 ◽  
Author(s):  
H Khoramishad ◽  
A Akhavan-Safar ◽  
MR Ayatollahi ◽  
LFM da Silva
Keyword(s):  
Longitudinal Strain ◽  
Critical Value ◽  
Critical Distance ◽  
Static Strength ◽  
Lap Joints ◽  
Substrate Thickness ◽  
Adhesively Bonded ◽  
Single Lap Joints ◽  
Failure Loads ◽  
Two Parameters

A critical distance based method was proposed for predicting the strength of adhesive single lap joints. Using this method, the failure of SLJs was predicted when the longitudinal strain along the adhesive mid-plane reached a critical value at a specific critical distance. The two parameters of the method including the critical longitudinal strain and the critical distance can be determined using experimental results. Several single lap joints with different overlap lengths and substrate thicknesses were manufactured and tested under quasi-static loading. It was found that the critical distance was independent of the overlap length and the substrate thickness while the critical longitudinal strain was found to be dependent on the substrate thickness. However, the effect of substrate thickness on the critical longitudinal strain decreased by increasing the substrate thickness. The correlation between the experimental and predicted failure loads was found to be very well.

scholarly journals Experimental and Numerical Study of Low-Velocity Impact and Tensile after Impact for CFRP Laminates Single-Lap Joints Adhesively Bonded Structure

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1016
Author(s):  
Chunxing Hu ◽  
Guibin Huang ◽  
Cheng Li
Keyword(s):  
Lap Joints ◽  
Low Velocity Impact ◽  
Adhesively Bonded ◽  
Low Velocity ◽  
Adhesive Film ◽  
Velocity Impact ◽  
Cfrp Laminates ◽  
Single Lap Joints ◽  
Impact Energies ◽  
The Impact

To investigate the mechanical behavior of the single-lap joints (SLJs) adhesively bonded structure of carbon fiber reinforced polymer (CFRP) laminates under the low-velocity impact (LVI) and tensile-after impact (TAI), tests and simulations were carried out. A finite element model (FEM) was established based on the cohesive zone model (CZM) and Hashin criterion to predict the damage evolution process of adhesive film, intra- and inter-laminar of the SLJs of CFRP laminates, and its effectiveness was verified by experiments. Moreover, three different overlap lengths (20 mm, 30 mm, and 40 mm) and four different impact energies (Intact joint, 10 J, 20 J, and 30 J) are considered in the present study. Finally, the effects of different impact energies and overlap lengths on the residual strength of SLJs after impact were discussed. The results divulged that numerical results of impact and TAI processes of SLJs were in good agreement with experiment results. During the impact process, the damage of the laminates was primarily fiber and matrix tensile damage, whereas the adhesive film was damaged cohesively; the areas of damage increased with the increase of impact energy, and the normal stress of the adhesive film expanded from the edge to the middle region with the increase of impact force. The influence of LVI on SLJs adhesively bonded structures was very significant, and it is not effective to obtain a higher impact resistance by increasing the overlap length. For the tensile process, the failure mode of TAI of the SLJs was interface failure, the surplus strength of the SLJs gradually decreased with the increase of the impact energy because of the smaller overlap length, the overlap length more than 30 mm, and the low energy impact has almost no effect on the residual strength of the SLJs.

Investigations on low-energy impact and post-impact fatigue of adhesively bonded single-lap joints using composites substrates

2019 ◽  
Vol 96 (15) ◽  
pp. 1326-1354 ◽  
Author(s):  
Wei Huang ◽  
Lingyu Sun ◽  
Lijun Li ◽  
Le Shen ◽  
Bincheng Huang ◽  
...  
Keyword(s):  
Lap Joints ◽  
Low Energy ◽  
Impact Fatigue ◽  
Adhesively Bonded ◽  
Single Lap Joints ◽  
Energy Impact ◽  
Post Impact

The flexural behaviors of the impacted composite single-lap adhesive joints

2015 ◽  
Vol 22 (5) ◽  
Author(s):  
Emin Ergun ◽  
Hasan Çallioğlu
Keyword(s):  
Experimental Study ◽  
Impact Energy ◽  
Energy Levels ◽  
Composite Plates ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Single Lap Joints ◽  
Impact Tests ◽  
Impact Energies ◽  
The Impact

AbstractThis experimental study deals with the flexural behaviors of composite single-lap adhesive joints after impact tests. Increasing impact energies are applied at the center of the composite plates having three different overlap lengths. It is shown that the overlap lengths and impact energy levels affect considerably the impact responses of the composite single-lap joints. It is also shown that the bending stiffness of the composite increases with increasing overlap length. For this reason, after the impact tests, how these effects influence the flexural behaviors of the impacted composite lap joints was also investigated. The flexural loads of the impacted and non-impacted composite single-lap joints were determined and compared with each other. It is shown that the residual flexural loads after impact increase with increasing overlap lengths but decrease with increasing impact energy.

The Effect of the Boundary Conditions on the Impact Behaviors of Stitched Composite Lap Joints

2016 ◽  
Vol 25 (1) ◽  
pp. 096369351602500
Author(s):  
Emin Ergun ◽  
Ismail Gökkaya
Keyword(s):  
Boundary Conditions ◽  
Energy Levels ◽  
Composite Plates ◽  
Lap Joints ◽  
Transverse Impact ◽  
Adhesively Bonded ◽  
Bonded Composite ◽  
Infusion Method ◽  
Impact Characteristics ◽  
The Impact

In this study, transverse impact behaviors of stitch adhesively bonded composite lap joints having three different overlap lengths (20, 40 and 60 mm) at different energy levels are investigated. The effects of the boundary conditions (clamped-clamped and clamped-free) and three different span lengths (40, 60 and 80 mm) have been determined. The impacts energies are varied in a range from 5 J to 20 J. Vacuum assisted resin infusion method (VARIM) is used to manufacture composite plates. It is shown that the boundary conditions and span lengths affect considerably the impact responses of the stitch composites lap joints. The important impact characteristics of the composite lap joints are compared with each other and discussed. The observed damages of the composite lap joints are presented.

An Assesment of the Impacted Composite Single-Lap Adhesive Joints

2015 ◽  
Vol 31 (4) ◽  
pp. 433-439
Author(s):  
H. Çallioğlu ◽  
E. Ergun
Keyword(s):  
Experimental Study ◽  
Impact Energy ◽  
Energy Levels ◽  
Composite Plates ◽  
Lap Joints ◽  
Adhesive Joints ◽  
Single Lap Joints ◽  
Impact Energies ◽  
The Impact ◽  
Energy Profiling

AbstractThe aim of this experimental study is to investigate impact behaviors of the composite single-lap adhesive joints. The increasing impact energies, which are ranged from approximately 5 J to 30 J, are performed at the center of the composite plates having three different overlap lengths. It is shown that the overlap lengths and impact energy levels affect considerably the impact responses of the composite single lap joints. It is also shown that the bending stiffness of the composite increases by increase in the overlap length. An energy profiling method (EPM) is used to identify the penetration and perforation thresholds of composite lap joints. The damaged composite plates are visually inspected.

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