Papers by Keyword: Yielding Strength

Abstract: In most papers dealing with tension and/or compression tests, the conventional yield stress is determined either by an offset method (usually 0.2% strain) or by back extrapolation from the stress-strain curve. In our experiments on ECAP’ed Aluminium a transient hardening saturation (THS) is always observed during the compression tests, but not during the tensile tests. This THS occurs at a significantly lower stress than the conventional yield stress. The aim of the present paper is to determine which the “real” start of yielding is. Two different experimental approaches have been adopted, confirming that the THS stage is exactly the yielding stage. This is not unimportant because it increases the tension-compression asymmetry and hence the back-stress and kinematic hardening. The reason for this different behaviour between tension and compression can be ascribed to a different change in strain path with respect to the ECAP deformation.

Abstract: Several I-shaped steel beams reinforced by CFRP are unloaded at different levels and the mechanical properties are analyzed and compared. Five forms of I-shaped steel beam (beam without reinforced; reinforced beam in condition of non-unloading; reinforced beam in condition of 50% unloaded; reinforced beam in condition of 75% unloaded; reinforced beam in condition of completely unloaded) are analyzed and compared. Conclusions are made that the stiffness and yielding load of I-shaped steel beams reinforced by CFRP are improved and the bearing capacity is improved for certain degree when the beams are unloaded.