Abstract
Mechanics of double-lap Steel-to-CFRP adhesively-bonded joints loaded in tension are investigated experimentally using Digital Image Correlation (DIC) and Acoustic Emission (AE), analytically using a one-dimensional closed-form solution and numerically with Finite Element analysis. The double-lap bi-material joints are fabricated of a steel core adhesively bonded to two CFRP skins with adhesive thickness of ~ 8 mm, using an Epoxy-based and MMA-based adhesives. In order to capture the in-plane deformation of the joint, full field strain/displacement maps are obtained using DIC. This data is used to validate the shear-lag model predictions of the adhesive shear stress/strain distribution as well as the linear-elastic Finite Element Model (FEM) results. In addition, they are used to capture the susceptible damage locations and their effect on the displacement contour maps, strain distribution and load transfer between the joint's different constituents. A correlation between the DIC displacement and the AE signals is obtained for damage detection in both joints. Moreover, a good agreement amongst the analytical, FE and DIC strain/stress distributions along the bond-line is observed. This study introduces the analytical shear-lag model as an alternative to predict the stress state in thick-adhesive double-lap joints, with an acceptable level of accuracy and robustness.
Highlights
The use of adhesively-bonded double-lap joints (DLJs) is preferred over conventional joining techniques such as bolting, riveting and welding
Mechanics of double-lap Steel-to-CFRP adhesively-bonded joints loaded in tension are investigated experimen tally using Digital Image Correlation (DIC) and Acoustic Emission (AE), analytically using a one-dimensional closed-form solution and numerically with Finite Element analysis
This study introduces the analytical shear-lag model as an alternative to predict the stress state in thick-adhesive double-lap joints, with an acceptable level of accuracy and robustness
Summary
The use of adhesively-bonded double-lap joints (DLJs) is preferred over conventional joining techniques such as bolting, riveting and welding They offer many advantages including, for instance, the ability to join dissimilar materials such as steel and fiber reinforced composites, weight savings, improved stress distribution along the bond-line and enhancement of the corrosion and fatigue resistance characteristics [1,2,3]. They discussed the limitations of the classical analytical models which include: i) neglecting the adherends’ shear deformation, ii) assuming only linear adhesive response and iii) overestimating the stress at the end of the overlap by violating the stress-free condition This overestimation results in a conservative failure load prediction when designing DLJs. As an attempt to overcome these limitations, the improved shear-lag model, by Tsai et al [15] for double-lap adhesive ly-bonded joints, was proposed to take into account the shear defor mation in the adherends. A summary of the concluding remarks of this research study is provided
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