Thèse--Universit́e de Lille.

Thesis--University of Wisconsin-Madison. / Vita. Photocopy of typescript. Ann Arbor, Mich. : University Microfilms International, 1979. -- 21 cm. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 148-150).

Thesis (M.S.)--University of Wisconsin--Madison, 1982. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaf 98).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Thesis (Ph. D.)--University of Texas at Austin, 2005. / Vita. Includes bibliographical references.

Thèse--Univ. de Lille.

If a work-hardenable metal is deformed plastically by a tensile stress +σ0 and unloaded, its mechanical properties become anisotropic; in particular, though its tensile yield stress is now +σ0, it will deform plastically if compression stresses numerically smaller than σ0 are applied. This is known as the Bauschinger effect (Bauschinger 1886). When this research was commenced, very few experiments had previously been carried out to elucidate the effect as a function of the several possible variables and there was practically no satisfactory theory, except perhaps that of Masing (1923), which in any case could be severely criticised on purely theoretical grounds. It was clear that various classes of metals would probably show different types of effect. In particular the metals with face-centred and body-centred cubic lattices which deform by slip only, should show a very different effect from that exhibited by the metals of hexagonal lattice, where twinning plays an important part in the deformation. Single crystals might well show a different effect from polycrystals. In nominally pure metals the effect might well depend on grain size, elastic anisotropy, amount of previous work-hardening, temperature, purity, magnetic properties, degree of preferred orientation of a polycrystal, and orientation of a single crystal. In alloys the situation might be even more complex, especially if more than one phase were present. For the purposes of this present research it was decided to examine the effect thoroughly and systematically in polycrystalline metals deforming entirely by slip, and to carry out exploratory experiments on other metals and in other conditions, including in particular, polycrystalline hexagonal metals and single crystals. Studies of macroscopic mechanical properties alone are not usually very conclusive in establishing the mechanism of the physical processes occurring, and it seemed very desirable to obtain additional information by examining the accompanying changes of other physical properties. Some experiments on these lines are discussed in sections III and V. The exploratory experiments of sections III, V, VI and VIII were deliberately restricted usually to one metal under well-defined conditions, in view of limitations of time. It is hoped to extend these experiments in the near future.

No description available.

No description available.

The effect of the mean stress on the endurance limit is a matter of considerable academic and practical importance. So many variable and uncertain factors are involved that it is not surprising that many different formulas and theories have been proposed since the start of investigations into this subject in about 1858. In this thesis, factual data obtained in the course of tests planned primarily for the purpose of determining the effect of the mean stress are presented and discussed. A standard fatigue testing machine vas used for all the tests. Various mean stresses, both for axial-load and torsional tests, were employed. A critical examination of the proposed theories of fatigue failure has been made. The theory which considered that the inception of fatigue resulted from alternating shearing stress and that the resistance to fatigue was influenced by the magnitude and sign of the steady normal stress was found to explain best the damage done to the material structure. It has been the opinion of a number of investigators that the fatigue strength under axial-load is decreased by an increasing tensile mean stress and in torsion the fatigue strength is unaffected by the mean stress. The experiments done here clearly indicate that this conclusion is true. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate