Stress relaxation testing for creep design analysis of metals, ceramics and polymers

It is shown how creep data generated from stress relaxation tests may be used to optimize the development of new materials, perform design analysis, and evaluate the current creep strength for life management of operating components. The new framework has been termed Design for Performance. Although the analysis is made in terms of creep rates, it may be presented in the form of current design protocol based on pseudo stress-strain curves or elapsed time as a function of stress and strain. Examples of the methodology are drawn from superalloys, silicon nitride and several thermoplastics to illustrate the advantages over traditional long term creep testing.