Accession Number : ADA255127

Title :   Stochastic Models of Wavefront Propagation in Random Granular Media.

Descriptive Note : Final rept.,

Corporate Author : MICHIGAN STATE UNIV EAST LANSING DEPT OF MATERIALS SCIENCE AND MECHANICS

Personal Author(s) : Ostoja-Starzewski, Martin

Report Date : AUG 1992

Pagination or Media Count : 39

Abstract : Determination of the effects of material microscale randomness on wavefront propagation is the focus of this report. The study is set in the context of one-dimensional microstructures with material randonness, of high signal-to-noise ratio, being present in constitutive moduli and grain lengths. Two different, but related, categories of problems - transient waves in granular microstructures and acceleration wavefronts in nonlinear elastic/dissipative continua - are discussed. In the first category, special focus is placed on microstructures with nonlinear elastic grains and an extension to two- and three-dimensional wave propagation. In the second category, particular attention is given to the phenomenon of stochastic competition between dissipation and elastic nonlinearity in formation of a shock from an acceleration wave. Explicit formulas for critical inverse amplitudes are obtained and illustrated graphically for different cases of correlatedness between dissipation and elastic nonlinearity. Additionally, the problem of determination of random time to form a shock is discussed. The common thread of both problem categories studied here is the use of Markov diffusion processes in description of wave evolutions in one as well as two and three dimensions. Granular material, Microstructure, Stochastic, Markov process, Random media, Wave propagation.

Descriptors :   *STOCHASTIC PROCESSES, *GRANULES, *PSEUDORANDOM SYSTEMS, *WAVE PROPAGATION, *WAVEFRONTS, MODELS, NONLINEAR SYSTEMS, SHOCK WAVES, ELASTIC PROPERTIES, IMPACT ACCELERATION, PULSE AMPLITUDE, ACCELERATION, AMPLITUDE, ATTENTION, COMPETITION, DETERMINATION, DIFFUSION, DISSIPATION, MATERIALS, MEDIA, MICROBALANCES, MICROSTRUCTURE, NOISE, ONE DIMENSIONAL, PROPAGATION, RATIOS, SHOCK, SIGNAL TO NOISE RATIO, SIGNALS, THREE DIMENSIONAL, TIME, TRANSIENTS, STOCHASTIC CONTROL, MARKOV PROCESSES, MEDIA, NOISE(RADIO), RADIO WAVES.

Subject Categories : Mechanics
      Statistics and Probability
      Miscellaneous Materials

Distribution Statement : APPROVED FOR PUBLIC RELEASE