A numerical study on stress mitigation in through-thickness tailored bi-adhesive single-lap joints

Abstract

In bi-adhesive single-lap joints (SLJs), longitudinal grading of adhesive compliance leads to peak stress concentration to the bi-adhesive interface (due to mismatch in properties). Due to this additional stress concentration at the bi-adhesive interface, the failure initiation threshold is lowered. In this paper, the stress distribution in the compliance-tailored bi-adhesive joints is investigated numerically. Peak stress at the bi-adhesive interface is diffused by geometrically grading the bi-adhesive interface in the longitudinal and transverse (through the thickness) directions. Linear and non-linear (material and geometric) finite element (FE) analyses were performed for two different set of bi-adhesive bondlines and joint configurations. FE results were benchmarked with published experimental and numerical data. Peak peel stress and peak shear stress are decreased by 29–70% and 8%, respectively, when the bi-adhesive interface is graded geometrically in the transverse and longitudinal directions as opposed to longitudinal tailoring alone. Moreover, the bi-adhesive interface’s stress concentration is reduced significantly. This leads to a more homogeneous stress distribution throughout the bond-layer. A thorough investigation reveals that through-thickness compliance tailoring of the bi-adhesive in SLJ can be used to increase tolerance to high load levels, achieve uniform stress distribution along the bond-layer, and reach the optimum joint stiffness.

Highlights

• A new approach for stress mitigation involving through the thickness tailoring of adhesive is introduced

• Proposed approach is validated for two sets of bi-adhesive systems and two joint configurations

• Finite element results are validated with published experimental data

• Load carrying capacity of joints is enhanced by diffusing peak stresses away from the bi-adhesive interface

Keywords:

• Finite element stress analysis
• bi-adhesive single lap joint
• peel stress
• through thickness compliance tailoring
• joint design
• stress distribution
• interfaces

Disclosure statement

No potential conflict of interest was reported by the author(s).

Acknowledgment

The support from Science and Engineering Research Board (SERB), Govt of India is gratefully acknowledged, project number CRG/2020/001056.