FINITE ELEMENT SIMULATION OF RESIDUAL STRESSES IN DIFFERENT COLD-EXPANDED PLATE TIDCKNESS

• Main Author: Hashim, Mohd Hafizuddin
• Format: Final Year Project
• Language: English
• Published: Universiti Teknologi Petronas 2011
• Subjects: TJ Mechanical engineering and machinery
• Online Access: http://utpedia.utp.edu.my/7387/1/2011%20-%20Finite%20element%20simulation%20of%20residual%20stresses%20in%20different%20cold%20expanded%20plate%20thickness.pdf; http://utpedia.utp.edu.my/7387/

In aircraft and aerospace industry, the fastener holes are widely present because a lot of its mechanical parts need to be connected by rivets or bolts. However, these holes experience external forces which cause a tensile stress on the surface which lead to the futigue cracks and eventually lead to fatigue failure of the structure. Hence, cold expansion method has been used to improve the fatigue behaviour of structures by inducing compressive residual stresses around the ,holes when a tapered mandrel is forced through the fastener hole that is a little smaller than the mandrel. In this study, finite element simulations had been carried out for cold expansion process in order to determine the residual stresses field around two cold-expanded holes by varying the centre distance between two holes and the thickness of the materiaL Moreover, the effect of through thickness position has been investigated by considering the residual stresses distribution at different position such as at the entrance face, at the middle thickness and at the exit face of the material. Aluminium alloy 7075-T6 was used as the material of the model developed in ANSYS. The results show the effect of different adjacent holes distance on the residual stresses field. Moreover, the simulation has highlighted the effect of the plate thickness and the through thickness position on the residual stresses distribution.