Experimental and Numerical Aspects of Structure Integrity

Abstract

The paper presents an approach in solving the problem of fracture mechanics treatment of surface cracks, which are a typical source for the structural failure. Difficulties associated with predicting structural integrity is that the surface cracks are three dimensional, whereas fracture mechanics methods using characterization parameters as K_Ic, J_Ic, COD are derived from two-dimensional assumptions. The method proposed for the solution is based on consideration of the elasto-plastic stress—strain behavior independent on the collapse conditions. For the investigation and development of the method, systematic numerical and experimental investigations have been performed. The main goal of the verification part of the tests' program was to justify the proposed method and to demonstrate the transferability of data, i.e. use of measurements taken from simple test specimens for a prediction of failure in large and/or complex structural components. The agreement between the prediction and test results using proposed procedure is very good. It has been shown that the proposed method gives more accurate prediction of verification test results and is less conservative than the current methods. In all cases where unnecessary conservatism is undesirable this method is more advantageous.