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Reliable engine-weight estimation at the conceptual design stage is critical to the development of new aircraft engines. It helps to identify the best engine concept amongst several candidates. In this paper, the major enhancements to NASA's engine-weight estimate computer code (WATE) are described. These enhancements include the incorporation of improved weight-calculation routines for the compressor and turbine disks using the finite difference technique. Furthermore, the stress distribution for various disk geometries was also incorporated, for a life-prediction module to calculate disk life. A material database, consisting of the material data of most of the commonly used aerospace materials, has also been incorporated into WATE. Collectively these enhancements provide a more realistic and systematic way to calculate the engine weight. They also provide additional insight into the design tradeoff between engine life and engine weight. To demonstrate the new capabilities, the enhanced WATE code is used to perform an engine weight/life tradeoff assessment on a production aircraft engine. [DOI: 10.1115/1.1691980]

A stochastic model for crack initiation and growth under creep and creep-fatigue conditions is developed. The model was based on the damage accumulation along grain boundaries, critical damage needed for crack intitiation or growth and grain-boundary length. The model was also used to obtain the crack initiation and short-crack growth of 304 stainless steel. Results show that the model predicts mean crack initiation lives within 10% of experimental values.