The extension of semielliptical surface cracks in plates under cyclic tension and cyclic bending loading has been investigated. The analytical results compared different assumptions, applying local and weighted averaged ΔK values and the effect of crack closure. The experimental results showed that the developing crack front can be described fairly accurately by semiellipses. Applying local ΔK values for the prediction underestimates the developing crack aspect ratio a/c. Applying the weighted averaged ΔK or a crack closure factor improves the prediction.
The Versatile Affordable Advanced Turbine Engine (VAATE) program has been supporting the development of Alloy 10, a gasatomized powder metal (PM) superalloy. Funding for the program was provided by U.S. Air Force Research Laboratory (AFRL).Honeywell International, Rolls Royce -Allison Advanced Development Company (AADC), and Williams International have been jointly developing Alloy 10 for small and large gas turbine engine applications. Alloy 10 is a demonstrated industry leader in high temperature creep resistance, and has been produced using production-scale equipment for high pressure turbine disk applications. To address cost issues, the VAATE Alloy 10 project evaluated the relative differences between material densified by hot isostatic pressing (as-HIP) and material produced by extrusion followed by isothermal forging. The program was completed as a series of four tasks: (i) chemistry optimization, (ii) as-HIP compaction, (iii) HIP compaction plus isothermal forging for small engine applications, and (iv) extrusion plus isothermal forging for large engine applications. This report provides the status of the program, microstructures typical of the various Alloy 10 product forms, and a summary of initial mechanical properties data.
Abstract. Evidence of the physical and economic impacts of climate change is a critical input to policy development and decision making. The potential magnitude of climate change damages, where, when, and to whom those damages may occur across the country, the types of impacts that will be most damaging, and the ability of adaptation to reduce potential risks are all important and interconnected. This study utilizes the reduced-complexity model, Framework for Evaluating Damages and Impacts (FrEDI), to rapidly assess economic and physical impacts of climate change in the contiguous United States (U.S.). Results from FrEDI show that net national damages increase overtime, with mean climate-driven damages estimated to reach $2.9 trillion USD (95 % CI: $510 billion to $12 trillion) annually by 2090. Climate-driven damages are largest for the health category, with the majority of damages in this category from the valuation estimates of premature mortality attributable to climate-driven changes in extreme temperature and air quality (O3 and PM2.5). Results from FrEDI also show that climate-driven damages vary by geographical region, with the Southeast experiencing the largest annual damages per capita (mean: $9,300 per person annually, 95 % CI: $1,800–$37,000 per person annually), whereas the smallest damages per capita are expected in the Southwest region (mean: $6,300 per person annually, 95 % CI: $840–$27,000 per person annually). Climate change impacts may also broaden existing societal inequalities, with Black or African Americans disproportionately affected by additional premature mortality from changes in air quality. This work significantly advances our understanding of the impacts from climate change to the U.S., in what U.S. regions impacts are happening, what sectors are being impacted, and which population groups being impacted the most.
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