scholarly journals Experimental Study of the Influence of the Surface Preparation on the Fatigue Behavior of Polyamide Single Lap Joints

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1008
Author(s):  
Francesco Musiari ◽  
Fabrizio Moroni

The low quality of adhesion performance on polymeric surfaces has forced the development of specific pretreatments able to toughen the interface between substrate and adhesive. Among these methods, atmospheric pressure plasma treatment (APPT) appears particularly suitable for its environmental compatibility and its effectiveness in altering the chemical state of the surface. In this work, an experimental study on adhesively bonded joints realized using polyamide as substrates and polyurethane as the structural adhesive was carried out with the intent to characterize their fatigue behavior, which represents a key issue of such joints during their working life. The single lap joint (SLJ) geometry was chosen and several surface pretreatments were compared with each other: degreasing, abrasion (alone and followed by APPT) and finally APPT. The results show that the abrasion combined with APPT presents the most promising behavior, which appears consistent with the higher percentage of life spent for crack propagation found by means of DIC on this class of joints with respect to the others. APPT alone confers a good fatigue resistance with respect to the simple abrasion, especially at a low number of cycles to failure.

2018 ◽  
Vol 2018 ◽  
pp. 1-10
Author(s):  
Kai Wei ◽  
Yiwei Chen ◽  
Maojun Li ◽  
Xujing Yang

Carbon fiber-reinforced plastics- (CFRP-) steel single lap joints with regard to tensile loading with two levels of adhesives and four levels of overlap lengths were experimentally analyzed and numerically simulated. Both joint strength and failure mechanism were found to be highly dependent on adhesive type and overlap length. Joints with 7779 structural adhesive were more ductile and produced about 2-3 kN higher failure load than MA830 structural adhesive. Failure load with the two adhesives increased about 147 N and 176 N, respectively, with increasing 1 mm of the overlap length. Cohesion failure was observed in both types of adhesive joints. As the overlap length increased, interface failure appeared solely on the edge of the overlap in 7779 adhesive joints. Finite element analysis (FEA) results revealed that peel and shear stress distributions were nonuniform, which were less severe as overlap length increased. Severe stress concentration was observed on the overlap edge, and shear failure of the adhesive was the main reason for the adhesive failure.


2021 ◽  
Vol 63 (11) ◽  
pp. 1007-1011
Author(s):  
İsmail Saraç

Abstract This study was carried out in two stages. In the first step, a numerical study was performed to verify the previous experimental study. In accordance with the previous experimental study data, single lap joints models were created using the ANSYS finite element analysis program. Then, nonlinear stress and failure analyses were performed by applying the failure loads obtained in the experimental study. The maximum stress theory was used to find finite element failure loads of the single lap joints models. As a result of the finite element analysis, an approximate 80 % agreement was found between experimental and numerical results. In the second step of the study, in order to increase the bond strength, different overlap end geometry models were produced and peel and shear stresses in the adhesive layer were compared according to the reference model. As a result of the analyses, significant strength increases were calculated according to the reference model. The strength increase in model 3 and model 5 was found to be 80 % and 67 %, respectively, relative to the reference model.


2018 ◽  
Vol 53 (23) ◽  
pp. 3335-3346 ◽  
Author(s):  
Hamid Reza Borghei ◽  
Bashir Behjat ◽  
Mojtaba Yazdani

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.


2020 ◽  
Vol 102 ◽  
pp. 102674
Author(s):  
F. Ramezani ◽  
M.R. Ayatollahi ◽  
A. Akhavan-Safar ◽  
L.F.M. da Silva

2016 ◽  
Vol 93 (11) ◽  
pp. 879-895 ◽  
Author(s):  
R. Hunter ◽  
J. Möller ◽  
A. Vizán ◽  
J. Pérez ◽  
J. Molina ◽  
...  

2016 ◽  
Vol 145 ◽  
pp. 68-79 ◽  
Author(s):  
Mingxia Yao ◽  
Deju Zhu ◽  
Yiming Yao ◽  
Huaian Zhang ◽  
Barzin Mobasher

Author(s):  
SMJ Razavi ◽  
MR Ayatollahi ◽  
M Samari ◽  
LFM da Silva

This paper addresses numerical and experimental examination of the role of zigzag interface shapes on the load bearing capacity and fatigue life of adhesively bonded single lap joints. Aluminum adherends with non-flat zigzag interfaces were tested under both quasi-static and fatigue loading conditions. The quasi-static test results revealed that the non-flat adhesive joints have higher load bearing capacity compared to the conventional flat single lap joints. Comparative fatigue tests with different loading levels revealed that the non-flat zigzag single lap joint had considerably higher fatigue life than the conventional lap joint.


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