Failure Modelling of Rivets Using Non-Linear Fe Software Ls-Dyna

Abstract

[EN] In the aerospace field rivets are used to join different substructures. Modelling a large amount of rivets for simulation of an airplane in an impact scenario requires idealisation methods to be applied, since detailed FE modelling of rivets would be too expensive computationally. The aim of this thesis is to accurately model failure of these permanent fasteners under in-plane loading conditions using a detailed Finite Element Approach, which would allow rivet failure criteria to be identified and used in the mentioned idealisation methods at last. In particular, and to characterise the tensile and shear strength of universal head rivets MS20470AD5-6, an Arcan-type experiment is considered. An Arcan-type fixture that allows mixed-mode in-plane loading to be applied to the rivet is designed and manufactured for the present research. An FE model to represent the Arcan-type experiment is built and different material failure models are considered within LS-DYNA®. Results are obtained in terms of force-displacement curves to characterise the strength of the rivets under pure shear and pure tension loading. Besides, experimental testing is carried out with the designed fixture in pure shear and pure tension configurations. Digital Image Correlation procedure is used to track the displacement of the parts riveted whilst force is measured using a load cell. Differences between FE and experimental results motivated a concise research in understanding the potential reasons for this mismatching in force-deflection curves. Material properties for annealed aluminium were introduced and better agreement was obtained, showing the capabilities of the FE model. Besides, general guidelines to further develop this project are depicted at the end of this thesis