Rosenhain Centenary Conference - 2. Design implications for materials selection 2.4 High temperature mechanical properties as design parameters Discussion

Abstract

Evidently, ductility in the vicinity of stress concentrations is of immense importance, and should perhaps form one of the design criteria. It seems to me unlikely that there will be a simple relation between notch ductility under these circumstances, and ductility in a parallel sided uniaxial test. Perhaps the many uniaxial creep tests on parallel sided specimens should be supplemented by more on specimens with sharp notches in them. Another point brought out by Branch is the importance of taking the effect of biaxiality and triaxiality into account in design. It is unrealistic to expect that one could ever, or would ever wish to replace all uniaxial creep data with triaxial creep data, but we should at least know how the one relates to the other, and whether there is a unique relation. Can we get such information on properly designed test specimens, waisted or notched to give biaxial or triaxial stresses, or must we undertake the complex and costly testing of structures?