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A plasticity theory is developed for a specific type of material characterized by coplanar motion of dislocation. Several results of the theory are given which make an experimental evaluation of the theory straightforward. The results of a limited experimental program for a particular nickel-base alloy are presented.

Simplified governing equations for line length, velocity, and lure hydrodynamic characteristics are used to determine the depth at which a lure runs in typical noncommercial fishing. The hydrodynamic characteristics of five typical lures were determined experimentally and their line length-velocity-depth relations, as predicted by the governing equations, are reported graphically.

A general three-dimensional plasticity theory is presented for describing the plastic flow of homogeneous, isotropic rock. Normality of the deformation-rate vector to the yield surface is incorporated into the stress-deformation rate law used in the theory. The rock is assumed to be perfectly plastic or nonwork-hardening with a dependence of the yield strength on the hydrostatic component of stress. A particular type of yield surface, which is representative of the behavior of rock, is assumed in an application of the theory. The specific problem considered is the solution for the incipient plane flow under a flat lubricated punch.

An analysis of the statically indeterminate problem of the creep of a biaxially loaded, anisotropic hollow cylinder is presented. The anisotropy of the material leads to a nonuniform axial stress distribution which is evaluated by numerical techniques. Single crystal, tubular specimens of a nickel-base alloy were creep-tested at 1400 deg F with an crystallographic axis nearly coincident with the tube axis in order to evaluate the theoretical analysis. Comparison of predicted and measured creep rates shows fair agreement.

The orientation and stress dependence of the primary creep rate in single crystals of a nickel-base superalloy is predicted from crystallographic deformation mechanisms. An experimentally determined relationship between the deformation rate and applied stress is employed to calculate the independent contributions of each of the possible slip systems to the strain rate. Calculations were made for single crystals of a nickel-base superalloy tested in tensile creep at 1400 deg F, at which temperature the active slip planes are known to be {111}, and the slip directions either 〈110〉 or 〈112〉 at high or low strain rates, respectively. Comparison with measured primary creep rates showed the 〈110〉 contribution to be negligible and that while semi-quantitative agreement with the 〈112〉 analysis was obtained, an accurate prediction of creep rates may require inclusion of strain hardening in the analysis.

The solutions for three cases of retarded flow of a rigid-viscous material are given. These cases are: (a) Sliding parallel plates; (b) Couette flow between concentric cylinders; and (c) axial flow through a circular pipe. For Couette flow two types of loading-unloading paths are found. The results of this analysis explain some of the discrepancies between experimental results and theoretical predictions for a Bingham material.

Solutions are presented for the plane-strain plastic flow of rock under a pointed punch for two cases. In the first problem the indentation of a half space by a pointed punch is considered, and in the second the influence of a previous indentation on the formation of the next indentation is evaluated. The plasticity theory used in this analysis was developed by the authors earlier for rock mechanics applications. This theory incorporates a yield surface which is dependent on the mean normal stress and normality of the deformation rate vector to the yield surface. Work-hardening and elastic strains are neglected in the theory. These solutions furnish the analytical basis for some elementary experiments which may help to evaluate the theory.

The dependence of the stress field on a continuous periodically varying stiffness which approximates a layered material is studied. This dependence is compared to the solution for the usual approximation of converting this class of problems to the superposition of an anisotropic one and a residual boundary problem. The region of applicability of the usual approximation is found to be as expected geometrically but surprisingly large as far as variation of stiffness is concerned.