BOUNDARY LAYERS IN STRAIN-GRADIENT THEORY OF LINEAR ELASTICITY.
WATERVLIET ARSENAL N Y BENET LABS
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In a previous technical report based on couple stress theory the presence of an elastic boundary layer of minute thickness was established in which the states of stress and displacement differ essentially and significantly from classical elasticity solutions. The boundary layer effect becomes dominant for microbodies in composites. Based on strain-gradient theory a reinvestigation of the phenomena in elastic boundary layers is presented. Due to the fact that no reliable information on micromoduli is available, a mathematical parameter m is introduced which makes it convenient to compare the strain-gradient results 0m infinity with the couple-stress results m 0 and classical results m 2. It is found that the results in the strain-gradient theory may deviate from the classical elasticity results in either direction depending on whether m2 or m2. The couple stress theory, however, leads to over-corrected results which may be regarded as limits of strain-gradient results on the side of m2. Author