Residual stress identification in thin plates based on modal data and sensitivity analysis

Abstract

Residual stresses commonly arise in manufacturing, rolling, welding and heating of mechanical structures and they have a critical influence on fatigue strength, creep resistance and other properties of the structures. Therefore, identifying the residual stress distribution is crucial for quality assessment of these structures. To this end, this paper proposes a new non-destructive residual stress identification approach for thin plates using modal data. There are two key ingredients in establishing the proposed approach. The first is the parameterization of residual stress field by resorting to the Airy stress function so that residual stress identification is recast as a parameter identification problem. The second lies in the inverse identification of stress parameters through a sensitivity-based procedure. In doing so, stress parameter identification is formulated as a nonlinear optimization problem whose goal function is just least-squares of the misfit between the measured and calculated data, and then, modal sensitivity analysis and the trust-region constraint are introduced to iteratively get the solution. Numerical examples are conducted to verify the feasibility and accuracy of the proposed approach.