Creep life of ceramic components using a finite-element-based integrated design program (CARES/CREEP)

Journal Article · Thu Jan 01 04:00:00 EST 1998 · Journal of Engineering for Gas Turbines and Power

DOI:https://doi.org/10.1115/1.2818070· OSTI ID:290090

Powers, L M ^[1]; Jadaan, O M ^[2]; Gyekenyesi, J P ^[3]

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1. Cleveland State Univ., OH (United States)
2. Univ. of Wisconsin, Platteville, WI (United States)
3. NASA Lewis Research Center, Cleveland, OH (United States)

The desirable properties of ceramics at high temperatures have generated interest in their use for structural applications such as in advanced turbine systems. Design lives for such systems can exceed 10,000 hours. The long life requirement necessitates subjecting the components to relatively low stresses. The combination of high temperatures and low stresses typically places failure for monolithic ceramics in the creep regime. The objective of this paper is to present a design methodology for predicting the lifetimes of structural components subjected to creep rupture conditions. This methodology utilizes commercially available finite element packages and takes into account the time-varying creep strain distributions (stress relaxation). The creep life of a component is discretized into short time steps, during which the stress and strain distributions are assumed constant. The damage is calculated for each time step based on a modified Monkman-Grant creep rupture criterion. Failure is assumed to occur when the normalized accumulated damage at any point in the component is greater than or equal to unity. The corresponding time will be the creep rupture life for that component. Examples are chosen to demonstrate the CARES/CREEP (Ceramics Analysis and Reliability Evaluation of Structures/CREEP) integrated design program, which is written for the ANSYS finite element package. Depending on the component size and loading conditions, it was found that in real structures one of two competing failure modes (creep or slow crack growth) will dominate. Applications to benchmark problems and engine components are included.

• OSTI ID: 290090
• Report Number(s): CONF-960608--
• Journal Information: Journal of Engineering for Gas Turbines and Power, Journal Name: Journal of Engineering for Gas Turbines and Power Journal Issue: 1 Vol. 120; ISSN JETPEZ; ISSN 0742-4795
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
C CODES
CERAMICS
COMPUTER-AIDED DESIGN
CREEP
FINITE ELEMENT METHOD