Papers by Keyword: Ductile Metals

Abstract: By a theoretical consideration of a viscous body it has been deduced a formula for the description of the fatigue properties of ductile metals and plastic materials. This formula has been compared with experimental fatigue data of Wöhler-curves (S-N curves). For cellulose acetate, iron, copper, nickel, silver, zinc and, to a restricted degree, also for aluminum a sufficient accordance between the experimental data and the theoretical curves has been reached. With this procedure it is possible to determine fatigue limits for these materials. Similar results are obtained for the creep of brass. It is supposed that the cause of the fatigue limit is the near surface stress of the specimen.

Abstract: In this article we perform comparative analysis of the criteria of fracture during blade machining simulation, characterized by high intensity of the strain rate (about 10^-6 s^-1). For each 3D virtual experiment a milling processing model has been developed in DEFORM software package. The character of chip segmentation during the simulation was determined the accepted failure criterion. The adequacy of the model was evaluated by full-scale experiment based on geometry of real chips.

Abstract: The paper discusses an anisotropic continuum damage model. It takes into account the effect of stress state on damage and failure conditions as well as on evolution equations of damage strains. To validate the proposed framework experiments with biaxially loaded specimens and corresponding numerical simulations are performed covering a wide range of stress states. In addition, scanning electron microscope images of the fracture surfaces show different fracture modes corresponding to stress states revealed by numerical analyses.

Abstract: In the framework of percolation theory, a simple void-coalescence model combined with the constitutive relations for describing the stress relaxation and material softening during the void-coalescence process, name as the percolation-relaxation (P-R) model, is proposed to describe the dynamic tensile spallation of ductile metals. A critical damage is introduced and coupled into the model to identify the onset of the void coalescence. Mesoscopically, the critical damage corresponds to the critical intervoid ligament distance (ILD), indicating the start of transition from the void-growth to the void-coalescence.