An investigation on fatigue life evaluation and crack initiation of Al-GFRP bonded lap joints under four-point bending

Zamani, Pedram; Jaamialahmadi, Abdolrahman; Silva, Lucas F. M. da; Farhangdoost, Khalil

doi:10.1016/j.compstruct.2019.111433

Cited by 34 publications

(20 citation statements)

References 26 publications

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“…In order to obtain a uniform adhesive thickness, the overlap region was put under pressure using two clamps (Figure 2b). For ensuring a uniform adhesive thickness and its measurement, a procedure was applied based on the procedure used in a previous research performed by Zamani et al 20 The average thickness of the adhesive layer was measured as 0.12 mm with a SD of 0.02 mm.…”

Section: Preparation Of Specimensmentioning

confidence: 99%

“…Some research works were focused on examining different fatigue loading factors such as frequency, maximum fatigue load and load ratio as well as novel loading types on the endurance of SLJs. [16][17][18][19][20] Modification of the geometry of the bonding surface of the overlap in sinusoidal wavy or zigzag shapes can significantly improve the static strength and fatigue endurance of bonded joints. [21][22][23] The surface preparation of the adherends using either mechanical or chemical approaches can enhance the mechanical performance by affecting the surface roughness and chemical interaction between the adhesive and substrate.…”

Section: Introductionmentioning

confidence: 99%

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Investigating on the influence of multi‐walled carbon nanotube and graphene nanoplatelet additives on residual strength of bonded joints subjected to partial fatigue loading

NajiMehr

Mahmood

Zamani

et al. 2021

J of Applied Polymer Sci

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Adhesively bonded joints in engineering structures, especially automotive body structures, inevitably experience long or limited fatigue loading conditions. In this article, the shear strength of steel bonded lap joints reinforced by multi-walled carbon nanotube (MWCNT) and graphene nanoplatelet (GNP) were evaluated after being subjected to limited fatigue loading cycles. For this purpose, three specimen groups of neat, MWCNT, and GNP-reinforced joints (with 0.2, 0.5, 1.0, and 2.0 wt% contents) were prepared. After performing the static lap shear tests, fatigue testing of each specimen group was conducted under a maximum fatigue load of 50% of its average static failure load until complete separation of the substrates. Accordingly, limited fatigue loadings were applied to each specimen group for 30%, 50%, and 70% of its total fatigue life, and subsequently, a secondround static testing was performed to evaluate the residual strength of the joints.The results revealed that the maximum static shear strength improvements of MWCNT and GNP-reinforced joints were associated with incorporating 1.0 and 0.5 wt% particle contents. Moreover, for 0.2 and 0.5 wt% contents, the static strength of the joints reinforced by GNPs was 3.4% and 3.9% greater than that of MWCNTs reinforced joints. On the contrary, for 1.0 and 2.0 wt% filler contents, specimens including MWCNTs had 9.1% and 18.6% higher strength than GNP-reinforced ones. The highest fatigue life enhancements of 34.1% and 31% were obtained by adding 1.0 and 0.5 wt.% of MWCNT and GNP particles to the adhesive, respectively. It was concluded that, for 0.2 and 0.5 wt% contents, nanoparticle type did not have a noticeable effect on the residual strength of the joints after being subjected to fatigue loading for 30% of its total life. The specimens subjected to 50% and 70% of their total fatigue life indicated a minimum loss in the shear strength for the joints reinforced by dispersing 1.0 wt% of MWCNTs.

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Section: Preparation Of Specimensmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigating on the influence of multi‐walled carbon nanotube and graphene nanoplatelet additives on residual strength of bonded joints subjected to partial fatigue loading

NajiMehr

Mahmood

Zamani

et al. 2021

J of Applied Polymer Sci

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“…Geometrical discontinuities such as holes, notches, cracks, and non-uniformities in a structure could be considered as the causes of damage initiation and failure of structures (Zamani et al, 2019). As it is known, the fracture mechanics approach supposes an existing crack in the structure.…”

Section: Theoretical Overviewmentioning

confidence: 99%

On the influence of resin pocket area on the failure of tapered sandwich composites

Soleymani

Tahani

Zamani

2020

Advances in Structural Engineering

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Structural defects such as resin pocket area are inevitably created between surface and core of composite structures during the production of wind turbine blades using vacuum infusion process. In this article, four-point bending tests were performed on tapered sandwich composites to investigate the effect of resin pocket area on the mechanical strength, crack growth path, and failure mode. Specimens were in similar shape to wind turbine blade profiles, and a shear-dominant load was applied to the resin pocket area during the experiments. The extended finite-element method was applied in order to predict crack growth path and failure mode. The average static strength of the specimens including the small size of resin pocket area had almost no change in compare with the specimen with no resin pocket area. Moreover, the medium size of resin pocket area decreased the strength for 3.5% while the large size one enhanced it for 1.75%. Thus, it can be deduced that the defect area does not have a significant effect on the flexural strength of the sandwich composite tapered specimens, but it can arrest the crack. Therefore, the crack propagates in the opposite direction at the interface of the face and core. Although the resin pocket area arrests the crack, it was observed that the size of resin pocket area directly affects the crack growth and its path. The smaller resin pocket area leads to slower crack growth, and early collapse occurs for the larger size of defect area. So, the size of resin pocket area has considerable importance during manufacturing of such structures. Finally, numerical results have shown good agreement with experimental ones.

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“…The effect of stress ratio on fatigue life of the adhesive joint was considered negligible. Likewise, the durability and crack propagation of single lap aluminum-GFRP specimens bonded with 0.1mm twocomponent structural epoxy paste (Araldite 2015) were investigated for various load ratios in four-point bending tests by Zamani et al [9]. It was shown that crack initiation life was equal to almost half of the total life for a maximum fatigue load equal to 50% of the static failure load whereas it is negligible for maximum fatigue loads higher than 60% of the static failure load.…”

Section: Introductionmentioning

confidence: 99%

Unified methodology for characterisation of global fatigue damage evolution in adhesively bonded joints

Jaiswal

Kumar

Waele

2020

Frattura Ed Integrità Strutturale

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This paper reports on the development of a methodology for evaluating the fatigue damage evolution in single and double lap adhesively bonded joints subjected to constant and variable fatigue loading. First, a methodology is developed to monitor the evolution of permanent deformation, stiffness degradation and hysteresis losses of single lap joints subjected to constant amplitude fatigue load. During the test, the global deformation of the adhesive joint is monitored using digital image correlation (DIC). A MATLAB code is developed to analyse and visualize the evolution in stiffness degradation and energy dissipation during the course of a complete fatigue test. Hereto ellipses are fitted to the hysteresis loops in the recorded load-deformation data. The slope of the main axis of the ellipse and its enclosed area are extracted to determine stiffness and dissipated energy, respectively. Next, the methodology is optimized for implementation during fatigue testing of double lap joints with different bond line thicknesses. The results of the experimental study reveal a distinct relation between stiffness degradation and increase in hysteresis losses with increasing number of fatigue cycles or thus increasing fatigue damage.

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An investigation on fatigue life evaluation and crack initiation of Al-GFRP bonded lap joints under four-point bending

Cited by 34 publications

References 26 publications

Investigating on the influence of multi‐walled carbon nanotube and graphene nanoplatelet additives on residual strength of bonded joints subjected to partial fatigue loading

Investigating on the influence of multi‐walled carbon nanotube and graphene nanoplatelet additives on residual strength of bonded joints subjected to partial fatigue loading

On the influence of resin pocket area on the failure of tapered sandwich composites

Unified methodology for characterisation of global fatigue damage evolution in adhesively bonded joints

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