[PDF] Strain Gradient Effects In Microlayers eBook

Author : Frederick D. Day
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Page : 84 pages
File Size : 46,90 MB
Release : 1966
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An analytic solution is obtained for two composite-body problems employing the strain-gradient theory of elasticity as developed by Mindlin. The investigation is concerned with the effects produced by strain-gradients, especially bonding stresses in the vicinity of an interface separating two dissimilar materials when higher order contact conditions prevail at the common boundary. The composite body under consideration consists of an infinite elastic strip ('microlayer') embedded in two semi-infinite elastic regions. The first problem concerns the case of uniform tension at infinity applied in a direction perpendicular to the microlayer. The second considers simple shear applied at infinity parallel to the microlayer. It is shown that the stresses that develop in the vicinity of an interface may be at large variance with the classical results. The magnitude of these stresses may be many times greater than the classical values, thus emphasizing the uncertainty of the classical approach in this instance. This variance is very significant when one material is much more rigid than the other, as encountered in the practical case of composite materials.

Author : Glenn A. Hazen
Publisher :
Page : 114 pages
File Size : 30,46 MB
Release : 1966
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This paper presents an analytical solution to a boundary-value problem in linear elasticity where potential energy depends on strains and strain gradients. The problem considered is that of an infinite medium, containing a spherical cavity, subjected to uniaxial tension at infinity. Special attention is given to the stress concentration factor at the surface of the cavity and to some higher order stress-terms. Results show that the stress concentration factor, which depends on two characteristic lengths as well as on additional material parameters, can exceed the classical vlue. The hyperstresses are found to represent surface like phenomena; they dimish to zero away from the surface of the cavity. (Author).

Author : Michael A. Sadowsky
Publisher :
Page : 73 pages
File Size : 43,28 MB
Release : 1967
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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