Stress relaxation in screw fittings in cast AZ91D components
Tutor / director / evaluatorAndersson, Nils-Eric
Document typeMaster thesis (pre-Bologna period)
Rights accessOpen Access
This work studies the behavior of screw fittings in high temperatures (120°C). The screw fittings are casted in AZ91D magnesium alloy (9% Al, 1% Zn). This part is jointed together with an aluminum part and the fastener is a M5 bolt made of steel. These three parts form the model which is simulated using Finite Element Analysis (FEA) procedures. Creep behavior and thermal expansion are included in the simulation. The results show the importance of both phenomena for the stress relaxation. Besides, deformation due to creep is responsible of most of the relaxation found in the AZ91D part. The stresses get reduced up to 40 and 50% in some areas of the magnesium alloy part. However, all the parts remain in contact all the time assuring the usefulness of the model despite the stress reduction.
SubjectsScrews, Screw-threads, Strains and stresses, Magnesium alloys -- Fatigue, Materials at high temperatures -- Testing, Cargols, Rosques de cargols, Deformacions i tensions, Magnesi -- Aliatges -- Fatiga, Materials a altes temperatures -- Proves
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