The scaled boundary finite-element method—alias consistent infinitesimal finite-element cell method—for elastodynamics

Effect of inclusion size on mechanical properties of polymeric composites with micro and nano particles

The effect of the adhesive thickness on the bond strength of single-lap adhesive joints is still not perfectly understood. The classical elastic analyses predict that the strength increases with the adhesive thickness, whereas experimental results show the opposite. Various theories have been proposed to explain this discrepancy, but more experimental tests are necessary to understand all the variables. The objective of the present study was to assess the effect of the adhesive thickness on the strength of single-lap joints for different kinds of adhesives. Three different adhesives were selected and tested in bulk. The strain to failure in tension ranged from 1.3% for the most brittle adhesive to 44% for the most ductile adhesive. The adherend selected was a high-strength steel to keep the adherends in the elastic range and simplify the analysis. Three thicknesses were studied for each adhesive: 0.2, 0.5, and 1 mm. A statistical analysis of the experimental results shows that the lap shear strength incre...

Effect of Adhesive Type and Thickness on the Lap Shear Strength

It is well known that adhesive joints have their optimum strength for thin bondline thicknesses (0.1-0.5 mm). The most common analytical methods used for adhesive joint analysis show an improved strength with increasing bondline thickness. This erroneous trend in prediction is investigated in this article. It is found that the through-the-thickness stress distribution in the adhesive is the main cause for the errors. The stresses, both peel and shear, at the interface between the adhesive and the adherend are found to increase, after an initial decrease in the low bondline thickness range, with increasing bondline thickness while the average stresses decrease. This trend explains the trends found in experiments. Further, as experimental results have shown, a theoretical optimum bondline thickness is found.

Analysis and evaluation of bondline thickness effects on failure load in adhesively bonded structures

Cohesive and continuum mixed-mode damage models applied to the simulation of the mechanical behaviour of bonded joints

Stress intensity factor analysis of interface crack using boundary element method (Application of contour-integral method)

The effect of bond thickness on the fracture toughness of adhesive joints was investigated from a microstructural perspective, using compact tension (CT) adhesive-joint specimens with different bond thicknesses. The adhesive material was a rubber-modified epoxy resin with 12.5 wt% carboxy-terminated butadiene acrylonitrile (CTBN) elastomer. The shapes of the rubber particles dispersed in adhesive layers of damaged and undamaged specimens were observed with an optical microscope. The damage was distributed along the interfaces between the adhesive layer and the two adherends. The results show that the primary causes of variations in the fracture toughness of at adhesive joint with the bond thickness are not only a damage zone around a crack tip hut also the combination of a damage zone around a crack tip and additional damage zones along the interfaces.

Effect of Bond Thickness on the Fracture Toughness of Adhesive Joints

Mixed mode fracture criterion of interface crack between dissimilar materials

Thermal stresses, one of the main causes of interfacial failure between dissimilar materials, arise from different coefficients of linear thermal expansion. Two efficient numerical procedures in conjunction with the finite element method (FEM) for the stress intensity factor (SIF) analysis of interface cracks under thermal stresses are presented. The virtual crack extension method and the crack closure integral method are modified using the superposition method. The SIF analyses of some interface crack problems under mechanical and thermal loads are demonstrated. Very accurate mode separated SIFs are obtained using these methods.

Stress intensity factor analysis for an interface crack between dissimilar isotropic materials under thermal stress

The evaluation of a fracture from a thin layer constrained by a hard material is important in relation to the structural integrity of adhesive joints and composite materials. It has been reported that the fracture toughness of a crack in a ductile adhesive joint depends on the bond thickness, but the mechanism has not yet been elucidated clearly. In this study, the J-integral and the near-tip stress of a crack in an adhesive joint are investigated. It is determined that a decrease of the bond thickness increases the stress ahead of a crack tip, which results in the decrease of fracture toughness.

Toru Ikeda

Papers

Stress intensity factor analysis of interface crack using boundary element method (Application of contour-integral method)

Effect of Bond Thickness on the Fracture Toughness of Adhesive Joints

Mixed mode fracture criterion of interface crack between dissimilar materials

Stress intensity factor analysis for an interface crack between dissimilar isotropic materials under thermal stress

Failure of a Ductile Adhesive Layer Constrained by Hard Adherends