Integrated Software to Predict Material Degradation in Special Technology Coatings

ABSTRACT: The Air Force faces challenges related to selecting, maintaining and repairing coatings that protect and enhance the performance of critical components in gas turbine engines. Coatings must maintain performance despite experiencing several degrading mechanical, thermal and chemical impacts. CFDRC proposes to develop a physics based model of the reactive flow environment integrated with a material damage model of the multilayered coating and substrate, with the intent to increase our understanding of the environmental impacts imparted onto the coating and the degradation in performance as a response. In phase I, we will develop a reacting computational fluid dynamics based model for the exhaust environment. We will integrate a quasi-continuum materials model to predict damage due to thermal-mechanical stress imparted on the coating and substrate based on the cohesive zone finite element method (CZM). CZM is appropriate for modeling fracture in multi-layered systems, which includes, cohesive and adhesive failures leading to spallation and delamination. In follow on work the models will be adapted to specific coating technologies and expanded to include the thermal mechanical stress imposed by soot accumulation and particle impacts. BENEFIT: CFDRC will deliver a methodology and software toolkit capable of predicting the degradation of special technology coatings designed to protect components in gas turbine engines. Modeling is anticipated to enhance the development, application, repair and maintenance of coating systems that are critical to gas turbine operations. The modeling technologies translate to all specialty coatings used in the engines systems. Gas turbine engines are used by all branches of the DoD and numerous other government agencies for aerospace applications, transportation and power generation. These government agencies will benefit from the modeling toolkit with reduced sustainment cost. The commercial gas turbine engine market is $42 billion per year with current development efforts seeking new coating technologies to raise operating temperatures. The modeling methods developed in this work could greatly enhance those efforts.