Paper number 462

AUTOMATED SHIFT FOR TIME-TEMPERATURE SUPERPOSITION

Sangwook Sihn and Stephen W. Tsai

Department of Aeronautics and Astronautics, Stanford University
Durand 381, Stanford, California, 94305, USA

Summary

Time-temperature superposition has been used for long-term structural durability design with short-term accelerating tests at elevated temperatures. Knowledge of a master curve at a specific reference temperature along with time-temperature shift factors serves to completely characterize the material or the failure properties across an enormous spectrum of times through the temperatures. A user-friendly tool to automatically obtain the master curve, the shift factors and the reliability is developed, and applied to several non-destructive and destructive properties successfully. With the tool, the time-temperature shifting becomes fast, objective and user-independent. The automated shifting tool is useful for not only the design of the structures, but acceleration of the accelerating tests.

Keywords

durability design, time-temperature superposition, time-temperature shift factor, automated shift, generalized linear least-square fit, spreadsheet-based program.