Mesoscale diagnostics criteria of mechanical state and predestruction of cyclically loaded welded joints

The possibility is shown of mechanical state estimation, residual resource prediction and predestruction stage diagnostics of welded joints in multicyclic fatigue on the basis of measurement and analysis of irreversible displacements vector fields by the optical-television method. The main types of displacement fields before crack vertex and their evolution in the loading process are described. The new criteria are suggested that characterize fatigue destruction accumulation at the mesoscale level.