Effect of Thermal Residual Stresses on Bonded Structures Containing Cold Expanded and Bolted Holes

Abstract

Abstract. The primary focus of this investigation is to determine the distribution of thermal residual stresses that result during composite bonding processes, and the effect on stresses generated during the subsequent cold expansion of holes. Residual stress measurements were carried out using neutron diffraction techniques. Results show that the cold expansion process resulted in radial compressive stresses 3-4 mm from the edge of the hole and there was no significant effect of thermal residual stresses from the bonding process on the cold expansion and bolted stresses.

Energy-Resolved Neutron Imaging for Reconstruction of Strain Introduced by Cold Working

“…In addition, to increase the reliability and lifetime of these joints, not only are these holes treated by a cold expansion procedure, but reinforcement by special laminates is also being investigated at the present time. GLARE (glass-reinforced aluminium laminate) is one of the possible solutions being considered for fatigue resistance in critical areas for aerospace applications [25][26][27]. Such laminates typically consist of several thin layers of metal (typically aluminium) interspersed with bonded layers of glass fibers.…”

“…The two cold-expanded holes had a final diameter of 6.27 mm after split-sleeve cold expansion treatment, which consists of pulling an oversized mandrel through a lubricated split-sleeve. This process introduces residual stresses in area adjacent to the hole [26,27]. One side of the plate had GLARE reinforcement.…”

Fatigue performance of bonded crack retarders in the presence of cold worked holes and interference-fit fasteners

“…These are typically a combination of advanced alloy parts reinforced with highly damage-tolerant materials that are adhesively bonded together. Amongst various bonded crack retarder materials, GLARE fibre-metal laminate has been considered as the best candidate owing to low weight, low thermal residual stresses after bonding at elevated temperature, and excellent fatigue and impact performance [5][6][7][8][9][10]. Therefore, GLARE was chosen as the crack retarder material for this research.…”

A comparison of fatigue crack growth performance of two aerospace grade aluminium alloys reinforced with bonded crack retarders

“…In application, curing at elevated temperature is a requirement based on aircraft operation conditions. Among various materials, the fibre‐metal laminate GLARE has been shown to be most effective owing to its low density, low residual stress arising from curing straps at elevated temperature, and improved fatigue and impact performance . In previous work, application of GLARE bonded crack retarders showed large benefit in AA2024 and AA7085.…”