Tolga Dursun and Costas Soutis
The purpose of this paper is to investigate the effect of fastener geometry (protruding head and countersunk fastener) and friction coefficient on the stress distributions around…
Abstract
Purpose
The purpose of this paper is to investigate the effect of fastener geometry (protruding head and countersunk fastener) and friction coefficient on the stress distributions around the hole of the double-lap single bolted aluminium alloy joints.
Design/methodology/approach
3D finite element analyses of double-lap bolted 7075-T6 aluminium joints were carried out. An elastic-plastic multi-linear kinematic hardening material behaviour was assumed for the Al alloy. Contact was defined using an augmented-Langrange contact algorithm, including the friction effect. Bolt clamping force and remote axial tensile loading were applied in two load steps and their separate and combined effects on the joint behaviour were investigated for two types of fastener configurations.
Findings
It was observed that bolt clamping reduces the axial tensile stress at the hole edge by introducing a through-thickness compressive stress. This reduction in stress concentration may have a beneficial effect on the fatigue life of the joint. Second, bolt clamping reduces the bearing stress at the fastener hole by creating a frictional force between the joint plates. Results showed that the joint with protruding head fastener shows lower tensile stress concentration, and lower bearing stress, near the bolt hole of the middle plate.
Originality/value
Bolt clamping force reduces both the stress concentration near the hole edge and the bearing stress at the hole by creating a frictional force. Joint with a protruding head fastener may lead to higher load carrying capability and improved fatigue life. Friction coefficient affects the stress levels around the bolt hole.
Details
Keywords
Mehdi Keikhosravy, Reza Hashemi Oskouei, Payam Soltani, Akin Atas and Constantinos Soutis
The purpose of this paper is to investigate the effect of geometric variables on the stress and strain distributions, as well as non‐linear deformation behaviour of aluminium…
Abstract
Purpose
The purpose of this paper is to investigate the effect of geometric variables on the stress and strain distributions, as well as non‐linear deformation behaviour of aluminium alloy 2024‐T3 single‐lap bolted joints loaded in tension.
Design/methodology/approach
The study has been conducted by using numerical and experimental approaches. In the numerical part, 3D FE models were generated using ANSYS software for different e/d and W/d ratios in which e and W are variables but the hole diameter (d) is constant. Stress and displacement results for each case have been discussed to better explain the mode of failure. In the experimental part, e/d=3 and W/d=6 ratios were selected as constant and testing specimens were produced accordingly. The aim was to obtain baseline experimental load‐strain and load‐displacement values for selected specimen geometry coordinated with the numerical analyses.
Findings
The good agreement between the experimental and numerical analysis provided confidence in the numerical methodology used to evaluate the different geometric variables. The results showed that the single‐lap bolted plates with optimised W/d and e/d ratios could shift the failure mode from net‐tension and shear‐out to bearing failure by directing the maximum damaging stresses from the stress concentration region and shear‐out planes towards the bearing region, leading to higher failure loads.
Originality/value
The paper develops a FE model of single‐lap bolted joints with a non‐linear material model and investigates 3D stress analysis as well as non‐linear deformation behaviour of bolted plates; optimisation of plates' width (W) and edge distance (e) to control failure modes; and bigger W/d and e/d ratios shift net‐tension and shear‐out to bearing failure mode.