Application of path-independent sensitivity integrals in thermographic identification of defects

摘要

The detection of surface or internal cracks, inclusions or voids as well as their location, orientation and size is performed using measurements of surface temperature either at some selected points or on selected surface areas or lines. On the basis of results of measurements, an inverse steady heat transfer problem is formulated and next solved. The inverse solution is constructed by minimizing the properly defined distance norm of measured and model temperatures. In this stage of research the real measurements are numerically simulated. The model temperature distribution is calculated using the finite element model of a structure, while in minimizing the distance norm functional the gradient-oriented methods are used. The proper sensitivities of introduced identification functional with respect to translation, rotation and scale change of defect are calculated using a new class of path-independent sensitivity integrals.