Accession Number : ADA258404


Title :   Computer Modelling of Cyclic Deformation of High-Temperature Materials


Descriptive Note : Technical progress rept. 16 Mar 1991-15 Nov 1992


Corporate Author : FAIRFAX MATERIALS RESEARCH INC ALEXANDRIA VA


Personal Author(s) : Duesbery, M S ; Louat, N P


Full Text : https://apps.dtic.mil/dtic/tr/fulltext/u2/a258404.pdf


Report Date : 16 Nov 1992


Pagination or Media Count : 30


Abstract : Current methods of lifetime assessment leave much to be desired. Typically, the expected life of a full-scale component exposed to a complex environment is based upon empirical interpretations of measurements performed on microscopic samples in controlled laboratory conditions. Extrapolation to the service component is accomplished by scaling laws which, if used at all, are empirical; little or no attention is paid to synergistic interactions between the different components of the real environment. With the increasingly hostile conditions which must be faced in modern aerospace applications, improvement in lifetime estimation is mandated by both cost and safety considerations. This program aims at improving current methods of lifetime assessment by building in the characteristics of the micro-mechanisms known to be responsible for damage and failure. The broad approach entails the integration and, where necessary, augmentation of the micro-scale research results currently available in the literature into a macro-scale model with predictive capability. In more detail, the program will develop a set of hierarchically structured models at different length scales, from atomic to macroscopic, at each level taking as parametric input the results of the model at the next smaller scale. In this way the known microscopic properties can be transported by systematic procedures to the unknown macro-scale region. It may not be possible to eliminate empiricism completely, because some of the quantities involved cannot yet be estimated to the required degree of precision. In this case the aim will be at least to eliminate functional empiricism.


Descriptors :   *COMPOSITE MATERIALS , *DISPERSION HARDENING , HIGH TEMPERATURE , NICKEL ALLOYS , MOLYBDENUM COMPOUNDS , SILICON CARBIDES , CREEP , DEFORMATION


Subject Categories : Laminates and Composite Materials


Distribution Statement : APPROVED FOR PUBLIC RELEASE