Numerical Prediction of the Fatigue Life of Complex Riveted Structures

Abstract

In this study, a numerical prediction methodology used to evaluate the fatigue life of complex riveted aluminum alloy structures subjected to variable amplitude loads is presented. This methodology is based on the combination of experimental fatigue tests with the structural stresses approach to generate S(N) curves. Single-riveted specimens (Al5052-H36) with different characteristics (rivet diameter, sheet thickness, assembly configuration) were first tested experimentally. Using a simplified finite element model (FEM) and a probabilistic model to compute the structural stress of these tested samples, fatigue curves for each type of failure encountered during testing (sheet metal and rivet) with a confidence interval were generated. Of the probabilistic models that were studied, the Stüssi model was the most effective to correlate the experimental results. The proposed methodology was then combined with Miner’s law to predict the fatigue life of complex riveted structures subjected to variable amplitude loading. Using the proposed methodology, satisfactory predictions of the fatigue life of multi-rivet specimens and a structural assembly from a recreational vehicle subjected to variable amplitude loads were obtained without the need to use a complex finite element model for the riveted joints. The methodology proposed in this paper is efficient and quick to use, can be used for various states of stress, and is well suited for structural or fatigue optimization problems.

Keywords

• fatigue
• rivet lap joint
• structural stress
• SN curve
• numerical model