Approximate estimation of strain-hardening creep deformation

Abstract

It is demonstrated that creep deformations of a structure based on strain-hardening behaviour are bounded by time-hardening and total-strain solutions. The bounds are not exact, but it is shown that any error is small compared with the difference between the exact solution and the approximate solution when the superposition method (1)∗ is used. As this difference is itself small compared with overall deflections (2) (3), the error due to assuming the strain-hardening solution to be bounded is negligible. It is also shown that strain hardening is asymptotic to the total-strain solution as time increases. A relatively rapid method is suggested for the approximate calculation of deflections, based on an approximate method devised previously (3) for total-strain theory. Numerical examples verify that total-strain theory is a better approximation to strain hardening than is time hardening, especially for large times.