List and describe several methods that have been used for ex

List and describe several methods that have been used for extrapolating short-time creep data to long-term applications. What are the potential pitfalls in using these methods?

Solution

Three commonly used methods for extrapolating short time creep data to long term applications are -

1. abridged method

2. the mechanical acceleration method

3. the thermal acceleration method

It is important to recognise that such extrapolations are not able to predict the potential of failure by creep rupture prior to reaching the creep design life. In any testing method it should be noted that creep testing guidelines usually dictate that test periods of less than 1% of the expected life are not deemed to give significant results. Tests extending to atleast 10% of the expected life are preferred wher feasible.