Stress concentration

About: Stress concentration is a research topic. Over the lifetime, 23250 publications have been published within this topic receiving 422911 citations.

Plate separation and anchorage of reinforced concrete beams strengthened by epoxy-bonded steel plates

Abstract: This paper deals with the problem of Anchorage at the ends of steel plates glued to the tensile faces of reinforced concrete beams. A simple theoretical study of the force systems at the plate/glue and the glued concrete interfaces is presented. This suggests that high stress concentrations and peeling forces are present at the ends of the plates when the composite beam is loaded in flexure. Tests carried out to investigate the effectiveness of different Anchorage arrangements are described in detail. The results from these tests confirm that, at the ends of the plates, interface stress concentrations exist, which have limiting peak values in the region of root 2 x tensile splitting strength of the concrete. Theoretical interface bond stresses, based on simple elastic behaviour, are found to have no consistent relationship to the measured peak values. However, if the maximum (unreduced) plate thickness is always used in these calculations, a simple method is proposed for obtaining a reasonable assessment of the peak stress. The efficiency of the different Anchorage details is discussed, and it is shown that the use of additional glued anchor plates gives the best results. These plates overcome the problem of Anchorage failure and enable the full theoretical flexural strength to be achieved, together with ductile behaviour.(a)

A model for the effect of grain size on the yield stress of metals

Abstract: It is proposed that the grain-size dependence of the yield stress of metals is due to the elastic incompatibility stresses at the grain boundaries. For clarity, the process of yielding is divided into three stages. In the first stage (prior to microyielding), the differences in elastic properties arising from the elastic anisotropy of adjacent grains establish localized stress concentrations at the grain boundaries. In the second stage, the stress concentrations at the grain boundaries result in localized plastic flow; this is the microyield region. The generation and motion of these 'geometrically necessary' dislocations attenuates the stress concentrations; a work-hardened grain-boundary layer is formed. As the stress is increased, the polycrystalline metal acts as a composite material consisting of a continuous network of a work-hardened grain-boundary material and discontinuous bulk material. The bulk is prevented from flowing plastically because the continuous network of work-hardened grain-...

A Mechanical Determination of Biaxial Residual Stress in Sheet Materials

Abstract: A method is given for determining the residual stress in a sheet material by removing successive uniform layers of material from the surface of a test specimen and measuring the resulting curvature. From the condition of equilibrium of a free specimen, a stress vs curvature relation is derived which holds over the depth to which material has been removed. The method applies when the stress is constant in the plane of the specimen and varies through the thickness. An experimental technique is described which is believed to satisfy the essential requirement that the removal of surface layers should not affect the stress in the remaining material, and a practical example is given.