Effect of the adhesive thickness on butt adhesive joints under torsional loads

Adhesive joints are extensively used in diverse industrial applications, exploiting the improved mechanical performance they offer over classical mechanical joining methods. To effectively design adhesive joints, it is first necessary to determine the mechanical properties of the materials being used (e.g. the adhesives and adherends). In this work, an epoxy based structural adhesive was characterized under tensile and shear loads using butt joints with solid adherends. The tensile tests were performed in a universal tensile machine and the shear tests were carried out in a torsional testing machine that ensures perfect alignment of the specimens and avoids any spurious bending moments, compression and tension loads during the test. The effect of adhesive thickness on the tensile and shear properties of the adhesive was evaluated, showing that under torsional loads there is a significant effect of the adhesive layer thickness on the shear strength and stiffness of the adhesive

Functionally graded adhesive joints using magnetic microparticles with a polyurethane adhesive

The present work focuses on using a recently proposed method to create functionally graded adhesive joints using a polyurethane adhesive and iron microparticles. Functionally graded joints were created with the application of a suitable magnetic field in the centre of the overlap region. This field is able to move the iron microparticles and create a tailored particle distribution. The main goal of this work was to create a particle concentration gradient that changes from particle rich in the middle of the overlap to poor in the ends. Consequentially, the stiffness of the resulting composite is made to vary along the bondline. A numerical simulation was performed to determine the optimal distance between the magnet and the adhesive layer as well as the application time of the external magnetic field. In order to assess the influence of the iron particles on the adhesive, different particle amounts were experimentally considered and two particles distributions were evaluated (uniform and graded distributions). The predicted particles trajectories were validated through a study of the single lap joint (SLJ) fracture surfaces, showing that the magnetic particles follow the magnetic field lines towards the middle of the overlap. Also, by observing the same fracture surfaces, the recently proposed method was validated, a non-uniform particle distribution. Finally, SLJs containing 1% of iron microparticles with a graded distribution were found to exhibit the best mechanical performance. Thus, this method has been demonstrated to be a viable technique to enhance the mechanical properties of bonded joints, leading to a more uniform stress distribution along the bondline

A comprehensive review on structural joining techniques in the marine industries_July 2021 (IAMaC 2021)

Since many modules of a ship cannot be practically reduced to a single structure, joining technologies are employed to join various substructures and transfer loads between the different components. These joining methods include welding, mechanical fastening, adhesive bonding, overlamination, and hybrid joining. In the current study, a comprehensive review has been conducted on the mechanical performance of the common joining techniques in the marine industry. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101006860 (FIBRE4YARDS project)

A comprehensive review on structural joining techniques in the marine industries_July 2021 (AB 2021)

Since many modules of a ship cannot be practically reduced to a single structure, joining technologies are employed to join various substructures and transfer loads between the different components. These joining methods include welding, mechanical fastening, adhesive bonding, overlamination, and hybrid joining. In the current study, a comprehensive review has been conducted on the mechanical performance of the common joining techniques in the marine industry. This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No 101006860 (FIBRE4YARDS project)

Geometry and adhesive optimization of single-lap adhesive joints under impact

The use of composite adhesive joints increased in the last decades through structural applications, comprising the aeronautical and automotive industries. Contrary to the static loading case, in many real situations, adhesive joints are subjected to impact loads, such as in the event of vehicle crashes. Despite this fact, numerical modelling of this loading type is seldom addressed in the literature. This work evaluates the effect of the overlap length (LO) and adhesive type on the strength of composite single-lap joints (SLJ), when impact loaded, through experimental tests and cohesive zone models (CZM). Two different types of adhesives were tested (Araldite® AV138 and Sikaforce® 7752), keeping constant the composite adherends with unidirectional lay-up. The joints were subjected to a drop test and validated through the numerical model, by the analysis of stresses and damage, predicting the joints’ strength for different geometries and adhesives. It was concluded that the increase of LO increases the joint strength, especially in those with a more flexible adhesive (Sikaforce® 7752), since this type of adhesive prevents significant stress concentrations, and being a ductile adhesive, provides the ability to absorb peak stresses. The impact CZM was able to predict the impact joints’ strength with good accuracy.info:eu-repo/semantics/publishedVersio