Abstract
This work deals with the notch sensitivity of sharp notches under multi-axial fatigue loading. The main discussion concerns the differences in notch sensitivity at high cycle fatigue regime, between tensile, torsional and combined loading. For this comparison, this paper considers a large set of fatigue experimental tests and several computing simulations analyzed with several notch theories for predicting fatigue life of a component. The considered experimental data, taken from literature, deal with the fatigue behavior of cast iron circumferentially V-notched specimens under tension, torsion, and combined loading mode. This paper tries to apply several techniques for theoretical strength assessment and to compare different procedures. The examined procedures need the computation of many parameters, focusing on the importance of using the tensile resistance to set these parameters or using both tensile and torsion resistances. However, the improvements obtained by means of the more complex procedures are not noteworthy, compared to the overall scatter. In author’s opinion, the differences in notch sensitivity under tensile and torsional loading remain questionable.
Highlights
The well-known problem of estimating the fatigue life of severely notched components, in the literature, is comprehensively studied, regardless of the material: for example carbon steel [1], titanium alloy [2] or polycrystals [3]
Many procedures in the last years came up to provide for this problem and many researchers are studying the way to predict the resistance of a notched component without specific experimental tests
One or more characteristic lengths lead all these theories. These lengths are calibrated on reference cases: for instance, the pure tensile and torsion tests; but, is it necessary to study all the different cases? What about the load ratio? Is the combined in phase/out-of-phase test influenced by the pure torsion sensitivity or tensile strength knowledge is sufficient? From applicative point of view, every current influencing factor requires a model and usually the introduction of a specific coefficient to be evaluated; at least one further undetermined coefficient should be fitted for every influencing factor introduced
Summary
The well-known problem of estimating the fatigue life of severely notched components, in the literature, is comprehensively studied, regardless of the material: for example carbon steel [1], titanium alloy [2] or polycrystals [3]. For the “notch sensitivity” modelling, Peterson [5] largely confirmed the need of introducing at least one length, material dependent, to be compared with the notch tip radius Another way, to predict fatigue life of notched components, is obviously to perform several tests to build, for example, the SN diagram, but this strategy needs a lot of time and money. The aim of this paper is to understand the difference between setting the characteristic length only on the pure tensile test and setting on the pure tensile and on torsion resistance For this purpose, the paper takes the fatigue strength of cast iron specimens under tensile, torsion and mixed in-phase and out-of-phase combined load from [20] and it compares the possible expectations computed by means of different theories
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
