Date of Award


Degree Name

Master of Science




Calvin M. Stewart


In this work, a new constitutive model, the WCS model, is derived that combines the Wilshire equations with continuum damage mechanics (CDM) for the long-term prediction of creep deformation, damage, and rupture. Long-term creep data is expensive and time-consuming to obtain because conventional creep testing is real-time. There is a need to extrapolate long-term creep behaviors from short-term data. Models that can accurately predict long-term creep behavior over a wide range of boundary conditions are vital for design engineers. The classic Wilshire equations can accurately extrapolate the long-term stress-rupture, minimum-creep-strain-rate, and time-to-strain of various alloys as their functional form has an explicit description of stress and temperature dependency. Recently, the time-to-creep-strain equation has been exploited to generate full creep deformation curves; however, with the addition of a CDM model, the equations become suitable for finite element analysis (FEA). The Sinh model can predict creep deformation, damage, and has been implemented into FEA software; however it lacks a description of temperature-dependence which limits the range in which predictions can be made. The combination of the Wilshire and the Sinh model enables stress-rupture, minimum-creep-strain-rate, creep deformation, and damage predictions with explicit stress and temperature dependency. In order to accomplish this goal; (a) the current Wilshire equations are evaluated for one material in in different forms and (b) the new CDM-based WCS model is developed and the realistic performance of the model is assessed. The WCS model predicts creep behaviors such as stress-rupture, minimum-creep-strain-rate, damage evolution, and creep deformation with an explicit stress and temperature gradients. The explicitness of the stress and temperature gradients across makes the model suitable for FEA software. Parametric studies are performed on the WCS model and is observed that the model behaves in a realistic manner.




Received from ProQuest

File Size

86 pages

File Format


Rights Holder

Jaime Aaron Cano