The effects of notch geometry on fatigue life using notch sensitivity factor

Abstract

The notch sensitivity of a material is a measure of how sensitive a material is to notches or geometric discontinuities. Notch sensitivity is influenced by many parameters such as notch geometry. Three types of notch geometries, V-shape, U-shape and -shape notches of various sizes are considered in this investigation. Two steel alloys of high and low strength (designated by HS-steel and LS-steel) are used in this work. Stress concentration is obtained by numerical simulation and the literature and fatigue reduction factor is determined by experiment using rotating bending fatigue device, Moore. The results show that the notch geometry has profound effect on fatigue life of materials. For HSsteel this reduction is roughly about 50%. For LS-steel alloy, however, the reduction depends on fatigue life and varies from 20% for low cycle fatigue tests up to 75% for high cycles fatigue tests. The maximum and minimum fatigue life reduction occurs for the V-shape and U-shape notches, respectively. The Equations proposed by Hardrath and Peterson underestimate the fatigue reduction parameters, q and K f and it seems that they are not adequate for prediction of notch sensitivity and they must be used with care.

The Effect of Notch Geometry on Tensile Strength at Low and Intermediate Strain Rates

“…A comparison between the variations of yield stress versus notch length for brass and steel at the velocity of 5 mm s )1 is shown in Figure 23. It is interesting to note that the effect of v-notches on dynamic behaviour of materials examined in this work is quite similar to that observed by Majzoobi and Daemi [10] in their study of the effect of v-notches on fretting fatigue behaviour of the same materials. A typical result is shown in Figure 24.…”

“…However, there is lack of information about K t for ‐shape notches. Majzoobi and Daemi [10] obtained K t for all notch geometries by numerical simulation using finite element method. They verified their results by those reported in the literature [8 & 9].…”

Evaluation of component‐similar rotor steel specimens with a local probabilistic approach for LCF

“…On the other hand, a notch induced HCF strength weakening is observed for some materials. For example, Haibach and Matschke et al and Majzoobi and Daemi observed that for structural steels, Karry and Dolan for brass, and Bennet and Weinberg for certain aluminium alloys.…”

Reliability assessment of stress concentration performance state for a perforated composite plate under traction

“…If the components are subjected to cyclic loading for which the material cannot relieve such high stresses, they could suffer a sudden fracture that happens more promptly in comparison with unnotched structures. The presence of perforated holes or notches can reduce dramatically the fatigue life of components in some circumstances [4,5]. Many studies have dealt with the effect of holes of various shapes and dimensions on fatigue life of engineering components under cyclic loading [5,6].…”

“…The presence of perforated holes or notches can reduce dramatically the fatigue life of components in some circumstances [4,5]. Many studies have dealt with the effect of holes of various shapes and dimensions on fatigue life of engineering components under cyclic loading [5,6]. In the case of cut-outs and holes, edge bluntness and rotation were recognized to be significant design variables and a number of works have dealt with these effects on composite plates [7,8].…”