Abstract
Single-lap bolted joint is the widely applied technique in joining parts of aerospace and civil engineering structures, due to joint efficiencies where staggered arrangements are commonly adopted. This particular joint type exhibits secondary bending phenomenon due to eccentric loading path. Stress analysis enables the structure engineers to predict the failure path and maximum stress that may lead to catastrophic failures. Stress analysis study were carried out in multi-bolted woven fabric kenaf reinforced polymer (WKRP) joints with variation of lay-up types, hole configurations and plate thicknesses. 3-D FEA modelling implemented here explicitly incorporates out-of-plane deformation to provide better prediction upon crack initiation from maximum stress exhibited along the hole boundary. WKRP plates tested were failed in net-tension where the crack propagated normal to its applied stress. It was found that plate variation (i.e., lay-up types, hole configurations and plate thicknesses) correspondingly affect tangential stress distributions along its hole boundary. Current 3-D models used modulus properties from independent experimental work which regarded as smeared-out properties through their plate thickness. Staggered configurations demonstrated more evenly stress distribution to their adjacent bolts due to stress resistance diagonally and larger staggered plate width. Slightly contrast in lay-up types where larger tangential stress is exhibited in cross-ply due to more volume fraction of 0° fiber direction. Larger tangential stress in thicker plates associated to effective friction stress transfer to give higher failure load. Effects of secondary bending is more prominent in cross-ply and thinner plates, assumption of smeared-out properties is less good due to plate edge lifting, however, effect of secondary bending phenomenon in multi-bolted is lesser than single-bolted joints.
Highlights
Composites materials is commonly used as a part in structural applications in various engineering sectors especially in bridge and housing constructions due to outstanding specific stiffness and strength
Secondary bending in multi-bolts are less significant than single-bolt joints due to adjacent bolts able to restrain the plate edge bending as sliding occurred
It is expected that thinner plate failed in lower peak load and inability of adjacent bolt to transfer stress has led to detrimental effects
Summary
Composites materials is commonly used as a part in structural applications in various engineering sectors especially in bridge and housing constructions due to outstanding specific stiffness and strength. Experimental investigations on single-row CFRP three-bolts joints were investigated by McCarthy and Gray [6] and found that increased pitch distance, diameter of middle bolt, plate width leading to more evenly load sharing among adjacent bolts This corresponds to ability of joining plates to carry higher applied load as stress transfer to adjacent bolts were almost uniform. Consistence findings were found in Yun et al [13] in their FEA study of multibolted CFRP joints to determine the deformation shape and associated hole clearances They found that holes clearance in composites plates was higher at the exterior column (i.e., closest to the applied loading) and hole elongations decreased as further away from applied load. The stress distribution implemented here were following experimental datasets [14], subsequently discussed in discussion section
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