Abstract
The requirements for cleaner energy have driven industrial
gas turbines manufacturers to increase firing temperatures
and improve cooling of nozzles. The application
of high temperature alloys having adequate thermomechanical
requirements is critical, as assessed by low cycle
fatigue performance. The effect of higher firing temperatures
combined with higher cooling efficiencies has
lead to operating cycles where the level of plastic strain
imparted define component life. The capability of material
models to account for non-linear effects such as
ratchetting or shakedown, cyclic hardening or softening as
well as Bauschinger or relaxation effects have been highlighted
in this context. Neglecting these effects can lead
to over and under-conservative life assessment analysis,
while accounting for them using standard multilinear material
models lead to convergence issues in finite element
analysis. In this paper, Chaboche viscoplastic model has
been applied to a transient structural of a first stage gas
turbine nozzle. Fitting of the model based on experimen-
tal mechanical test data on MAR-M-247 alloy will be described,
followed by an overview of how the model may
be implemented to a benchmark nozzle thermo-mechanical
transient analysis. Finally the details how the Chabochetype
model has provided up to 50% decrease in computation
time when compared to using a standard multi-linear
material modelling approach.
gas turbines manufacturers to increase firing temperatures
and improve cooling of nozzles. The application
of high temperature alloys having adequate thermomechanical
requirements is critical, as assessed by low cycle
fatigue performance. The effect of higher firing temperatures
combined with higher cooling efficiencies has
lead to operating cycles where the level of plastic strain
imparted define component life. The capability of material
models to account for non-linear effects such as
ratchetting or shakedown, cyclic hardening or softening as
well as Bauschinger or relaxation effects have been highlighted
in this context. Neglecting these effects can lead
to over and under-conservative life assessment analysis,
while accounting for them using standard multilinear material
models lead to convergence issues in finite element
analysis. In this paper, Chaboche viscoplastic model has
been applied to a transient structural of a first stage gas
turbine nozzle. Fitting of the model based on experimen-
tal mechanical test data on MAR-M-247 alloy will be described,
followed by an overview of how the model may
be implemented to a benchmark nozzle thermo-mechanical
transient analysis. Finally the details how the Chabochetype
model has provided up to 50% decrease in computation
time when compared to using a standard multi-linear
material modelling approach.
| Original language | English |
|---|---|
| Title of host publication | ASME TurboExpo 2018 |
| Subtitle of host publication | Turbomachinery Technical Conference amd Exposition |
| Place of Publication | Oslo, Norway |
| Publisher | American Society of Mechanical Engineers |
| Number of pages | 11 |
| Volume | 7A: Structures and Dynamics |
| ISBN (Electronic) | 978-0-7918-5113-5 |
| Publication status | Published - Jun 2018 |