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The solution for an angular dislocation allows one to construct the fields for any polygonal loop by superposition. The paper presents the displacements induced by the angular dislocation in an elastic half space. In view of potential applications in geophysics, particular attention is paid to the elastic fields at the free surface. The surface data are seen to exhibit a very simple dependence on the elastic constants. RI~SUMt~On peut construire les champs 61astiques associ~rs ~. une dislocation en polygone par superposition de solutions au probl6me d'une dislocation angulaire. Nous pr6sentons les d6placements induits par une dislocation angulaire dans un demi-6space 61astique. En vue des applications g6ophysiques, les champs 61astiques sur la surface librc sont 6tudi6s en particulier. Nous montrons que les champs 61astiques sur la surface d6pendent des constantes 61astiques d'une fa¢on tr+s simple.

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The interface crack subjected to a combined tension-compression and shear loading is considered in the Comninou formulation, which by properly incorporating contact zones at the crack tips avoids contradictions, such as overlapping of material. It is shown that the resulting integral equation can be solved exactly. Moreover, simple asymptotic — yet very accurate — formulae are derived for the quantities of major physical interest and a comparison made with the previous results given by Comninou.

The work reconsiders the smooth receding contact between an elastic layer and a half space when the two bodies are pressed together. The analysis leads to a Fredholm integral equation of the second kind for an auxiliary function that is directly related to the contact pressure. An unexpected result is that the integral equation is homogeneous, and that finding the extent of contact can be viewed as an eigenvalue problem. The integral equation can be solved numerically to any required degree of accuracy, and the extent of contact and the contact pressure are computed for concentrated and uniformly distributed loads in both plane and axisymmetric problems. The present analysis confirms the results of Weitsman rather than Pu and Hussain over a wide range of mismatch in the elastic constants.

When a composite body consisting of two isotropic and elastic phases is subjected to prescribed surface tractions, generally the stress field depends on three parameters involving the elastic con stants. If the composite is in a state of plane deformation, and there are no net forces on internal boundaries, however, the stress depends on only two combinations of elastic constants. Convenient constants for the composite material are proposed.

A simple one-dimensional model is described in which thermoelastic contact conditions give rise to nonuniqueness of solution. The stability of the various steady-state solutions discovered is investigated using a perturbation method. The results can be expressed in terms of the minimization of a certain energy function, but the authors have so far been unable to justify the use of such a function from first principles in view of the nonconservative nature of the system.

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