Fatigue Life Variability in Large Aluminum Forgings with Residual Stress.

摘要

As part of a larger residual stress modeling and standardization program, a computational assessment of the variability in fatigue crack growth life that can result from variability in residual stresses has been conducted. A detailed finite element analysis of the forge/quench/coldwork/machine process was performed in order to predict the bulk residual stresses in a fictitious aluminum bulkhead. The residual stress profiles on ten critical planes were used to calculate residual stress intensity factors for a range of crack types that are typical for aircraft structural details. These stress intensity factors were used in a standard, linear-elastic- fracture-mechanics-based fatigue crack growth algorithm in order to predict fatigue life for typical fighter aircraft spectrum loading. Calculations were made for residual stress profiles which reflected variability due to machined part placement within the parent forging.