Fatigue performance of metallic reverse‐bent joints

Abstract

A B S T R A C T Adhesively bonded lap shear joints have been investigated widely and several ideas have been proposed for improving joint strength by reducing bondline stress concentrations. These include application of adhesive fillets at the overlap ends and use of adhesive with graded properties in the overlap area. Another, less common, approach is to deform the substrates in the overlap area in order to obtain a more desirable bondline stress distribution. Previous work carried out by the authors on a number of different substrate materials indicated that a reverse-bent joint geometry is useful for increasing joint strength. Results from static stress analysis and experimental testing demonstrated that significant improvements could be achieved. This paper presents results of further work carried out to assess the fatigue performance of reverse-bent joints. Substrates with different yield and plastic deformation characteristics were used and the effects of different overlap lengths on strength were examined. The results of this research show that the improvements obtained under static tests conditions translate to even higher benefits in fatigue. The paper also explains the failure mechanism of the joints under fatigue loading.

Fatigue in Adhesively Bonded Joints: A Review

“…From the experimental results, it was found that adhesively bonded butterfly joints ( Figure 2) had a longer fatigue lifetime than those of the bonded butt joints under the same conditions. Fessel et al [3] proposed a reverse-bent joint geometry ( Figure 3) in order to improve fatigue performance of adhesively bonded joints. From their results, high improvement in fatigue performance was obtained.…”

Investigating the influence of the chamfer and fillet on the high-cyclic fatigue strength of adhesive joints of steel parts

“…In general, there are two approaches for fatigue lifetime prediction; namely, the stress-life approach [22][23][24][25][26][27][28][29][30][31][32] and the fatigue crack initiation/propagation approach. [33][34][35][36][37] In the former, a series of tests under various loads is performed in order to obtain the plot of stress vs. the number of cycles to failure, which is known as the S-N curve or Wohler's curve.…”

Fatigue strength evaluation and fracture behavior of joined dual phase steel/AA6061-T6 aluminum alloy

“…An example of that is the work published by Altan et al [6], where the results suggest that fatigue strengths of adhesively-bonded butterfly joints have a longer life span than those of the bonded butt joints under the same circumstances. Fessel et al [7] have investigated the effect of a reverse-bent joint geometry for the improvement of fatigue performance of adhesively bonded joints. The results suggest, that the improvements obtained under static tests conditions can be translated to even higher benefits in fatigue.…”