INFLUENCE OF HOLE-SIDE PLASTIC DEFORMATION ON THE ACCURACY OF RESIDUAL WELDING STRESS MEASUREMENT

In this paper,a new approach has been made to improve further the accuracy of residual welding stress measurement by the Small Blind-Hole Relaxation Method.The measurement error produced by the hole-side plastic deformation as a result of the stress concentration is also studied.It is discovered that the released strain ε determined in the case of σ>1/2σ_s,is composed of the pure elastic released strain ε_e and the plastic deformation ε_P around the hole.In calculation,ε_p should be subtracted from ε,and the residual stress calculated from ε_e would be the real value.By substituting ε_e for ε according to the improved method,the measurement error has been decreased from 19% to less than 2% when σ approaches σ_s.