TENSILE AND BENDING BEHAVIOR OF SINTERED ALLOYS - EXPERIMENTAL RESULTS AND MODELING

Sintered materials show a different stress-strain behavior when subjec ted to tensile or compressive loading, the response to compression bei ng characterized by a higher elastic modulus, yield stress, and strain hardening rate. These differences tend to make the bending behavior s omewhat more complex to analyze, particularly in the elasto-plastic fi eld, as compared to conventional materials, having equal mechanical pr operties under tension and compression. As a consequence, the use of w idely applied test techniques, such as the Three Point Bending (TPB), becomes more difficult for sintered materials, due to the lack of reli able analytical models capable of evaluating elasto-plastic stress-str ain distribution as a function of applied load and deflection. In the present investigation, the results of uniaxial tensile-compressive and bending tests conducted on sintered ferrous alloys characterized by d ifferent microstructures and porosity are reported and briefly discuss ed. Then an analytical model, specifically aimed to analyze the elasto -plastic monotonic behavior of a TPB specimen made with a material hav ing different tensile and compressive properties, is presented. Its pr edictions as regards load-deflection curves and elasto-plastic stress- strain distributions are compared with the results of TPB tests and of numerical (Finite Element) analysis, showing a fairly good agreement.