Lifetime calculation of adhesively bonded joints under proportional and non-proportional multiaxial fatigue loading: a combined critical plane and critical distance approach

ABSTRACT

This work presents an approach for lifetime calculation of adhesively bonded joints under proportional and non-proportional multiaxial fatigue loads. In-phase and out-of-phase fatigue data with varying stress ratio (R = 0.1 and −1.0) from several joint geometries (butt, scarf, thick adherend shear test and butt-bonded double pipe joints) was employed. The approach is based on the stress-life concept and the Theory of Critical Distances (TCD) considering point and line methods. Stresses were calculated using 2D-FEA with linear-elastic and elastoplastic adhesive behaviours. Non-proportional stresses were addressed by the Maximum Rectangular Hull method. Three failure criteria were investigated: Drucker-Prager (DPC): an invariant-based equivalent stress criterion; Findley (FC): a critical plane stress-based criterion; (c) Fatemi-Socie (FSC): a critical plane stress-strain-based criterion. The material parameter of each failure criterion was iteratively calibrated using fatigue data. The FSC had the worst prediction performance. The DPC presented good agreement with in-phase data, but less robust as the variation of its material parameter changed considerably the prediction accuracy. For both DPC and FC, the line method and linear-elastic models were capable of providing good predictions. The FC yielded the best predictions considering a normal sensitivity b_F > 1.0 for different stress ratios, in-phase and out-of-phase loads.

KEYWORDS:

• Adhesively bonded joints
• multiaxial fatigue
• critical plane
• critical distance
• stress-life approach

Acknowledgements

The IGF project No. 21112 N/P 1427 of FOSTA - Forschungsvereinigung Stahlanwendung e.V. Sohnstraße 65, 40237 Düsseldorf is funded by the Federal Ministry for Economic Affairs and Energy via the AiF within the framework of the programme for the promotion of joint industrial research (IGF) on the basis of a resolution of the German Bundestag.

V.C. Beber is grateful to the funding from CAPES, Brazil through the Science without Borders programme under the Grant BEX 13458/13-2.

Disclosure statement

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

Additional information

Funding

This work was supported by the Bundesministerium für Wirtschaft und Energie [IGF project No. 21112 N / P 1427]; CAPES [BEX 13458/13-2].