A Fracture-Based Criterion for Debonding Strength of Adhesive-Bonded Double-Strap Steel Joints

  • Akhrawat Lenwari Chulalongkorn University
  • Thaksin Thepchatri Chulalongkorn University
  • Prawit Santisukpotha Chulalongkorn University
Keywords: Double-strap joints, adhesive bonding, fatigue, debond detection, bi-material, reciprocal work contour integral, stress singularity.

Abstract

This paper addresses the debonding strength of adhesive-bonded double-strap steel joints. A fracture-based criterion was formulated in terms of a stress singularity parameter, i.e., the stress intensity factor, which governs the magnitude of a singular stress field near the joint ends. No existing crack was assumed. A total of 24 steel joint specimens were tested under constant amplitude fatigue loadings at stress ratio of 0.2 and frequency of 2 Hz. The joint stiffness ratio was slightly less than one to control the maximum adhesive stresses at the joint ends. To detect the debonding, a simple and practical technique was developed. The test results showed that the interfacial failure near the steel/adhesive corner was a dominant failure mode. The failure was brittle and the debonding life was governed by the crack initiation stage. The finite element analysis was employed to calculate the stress intensity factors and investigate the effects of the adhesive layer thickness, lap length and joint stiffness ratio on the debonding strength.

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Author Biographies

Akhrawat Lenwari

Department of Civil Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand

Thaksin Thepchatri

Department of Civil Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand

Prawit Santisukpotha

Department of Civil Engineering, Faculty of Engineering, Chulalongkorn University, Bangkok 10330, Thailand

Published In
Vol 16 No 1, Nov 8, 2011
How to Cite
[1]
A. Lenwari, T. Thepchatri, and P. Santisukpotha, “A Fracture-Based Criterion for Debonding Strength of Adhesive-Bonded Double-Strap Steel Joints”, Eng. J., vol. 16, no. 1, pp. 17-26, Nov. 2011.