Assessment of the Accuracy of Electromagnetic Field Calculations for non Destructive Testing

Various stochastic techniques, applied to solve inverse identification problems, require the generation of extensive databases obtained via numerical analysis of the corresponding direct problems. We focus on the problem of the accuracy of the electromagnetic computation. This is a critical issue in the context of the magnetostatic and eddy current NDT techniques, because the quantities of interest are often the difference between two close values. We first discuss the calibration of the numerical results, a technique that can be applied to nonlinear problems and reduces to superposition in the linear case. Linear problems possess several properties that can be exploited when performing numerical analysis. Finally, we discuss the question of error estimation. It is well known that the constitutive error approach provides bounds for global electromagnetic quantities. We show that upper and lower bounds are also available for local quantities in the linear case.