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FLOW AND FRACTURE OF METALS UNDER COMPLEX STRESS.
MICHIGAN UNIV ANN ARBOR DEPT OF ENGINEERING MECHANICS
The effects of severe initial prestrain on the response of a steel to complex stress states is investigated in a series of tube tests. The steel becomeshighly anisotropic, with a pronounced Bauschinger effect, so far as the resumption of plastic flow is concerned. A detailed analysis of the subsequent history of hardening shows that, in the later stages of plastic flow, it may be possible to simulate the behavior of the material with reasonable accuracy by means of an isotropic rigid-plastic model. Even after substantial prestrains plastic effective strain, 0.03 sufficient ductility remains to allow the redistribution of loads necessary for an ultimate strength plastic analysis of components. In Part I of the report a relatively complete study is made on the basis of plastic theory and it is shown that the stress distribution may be highly nonuniform even in a very thin cylinder moreover the distribution is dependent on the nature of the yield criterion and so cannot be known in advance. This circumstance renders the calculation of average stresses of limited value and it is better to deal directly with the applied tractions, a procedure which is adopted in the remainder of the report. Author
Final summary rept. 3 Mar 64-30 Sep 65,