Mechanical Stress Relief Simulation
A method of producing a known residual stress is sought so that methods for measurement of residual stress may be verified and calibrated. Equally, a clear classroom demonstration of a situation which causes residual stress and then relief of that residual stress is desired. It is shown in this paper that a flat aluminum specimen may be prepared with stress concentration discontinuities, and the part loaded so that the average stress and strain is below the yield point and the maximum stress in the discontinuity is beyond the yield point. Upon unloading from this condition, residual stresses will be present in the part, which may then be released by sawing through the part. Classical predictions of residual stress are correlated to a finite element model which simulates the loading, unloading, and cutting steps of the process. Observations on the difficulties inherent in experimentally accomplishing this process are also presented.