The effect of notch geometry on critical distance high cycle fatigue predictions

2005 ◽  
Vol 27 (10-12) ◽  
pp. 1623-1627 ◽  
Author(s):  
D LANNING ◽  
T NICHOLAS ◽  
A PALAZOTTO
2016 ◽  
Vol 258 ◽  
pp. 337-340 ◽  
Author(s):  
Mitra Delshadmanesh ◽  
Golta Khatibi ◽  
Martin Lederer ◽  
Michael Zehetbauer ◽  
Herbert Danninger

The high cycle fatigue response of Ti-45Nb alloy was investigated by using an ultrasonic fatigue testing system. The effect of notch geometry on the fatigue response was studied on samples with different circumferential grooves. The experiments showed a decrease of fatigue notch sensitivity with decreasing the notch radius. Finite element analysis (FEA) was conducted for calculation of the stress distribution in the samples and interpretation of the experimental results. Further, the lifetime of the alloy showed a strong dependency on the location of the defects and microstructural inhomogeneities. It was observed that at the same stress amplitude, early failure was caused by surface defects, while those with a longer lifetime failed due to cracks originating from internal flaws.


Author(s):  
Somnath Chattopadhyay

The high cycle fatigue strength of crack-like discontinuities in metallic structures has been investigated using the critical distance approaches. Two methods have been employed, (a) the point method, and (b) the imaginary crack method. In the point method, the stress at a critical point within the material volume is chosen as the governing fatigue criterion. The effective parameter is the distance “d” from the material surface, which is a material property and the reference parameter is the fatigue limit. The imaginary crack method involves introduction of a sharp crack at the root of a notch and the length of the crack, “l0” assumed a material constant. The point method leads to a practical design rule that uses fatigue design curves expressed in terms of equivalent strain range versus number of cycles to failure. The equivalent strain is evaluated at a distance “d” from the crack tip. In the imaginary crack method, the effective crack length is taken as the sum of the actual crack and the material parameter “l0”. It is concluded that the high cycle fatigue has a volumetric character and the proposed methods introduce the volume effect in the determination of stress and strain fields as well as the fatigue life. Using the material parameter, the number of cycles to initiate a fatigue has been determined.


2003 ◽  
Vol 38 (5) ◽  
pp. 443-452 ◽  
Author(s):  
L Susmel ◽  
D Taylor

This paper reports a comparative study of some recent methods developed for the estimation of high-cycle fatigue behaviour of components containing stress concentrations. It begins by reviewing some existing methods for the prediction of fatigue limits: the stress-life method, linear elastic fracture mechanics, the Kitagawa-Takahashi and Atzori-Lazzarin approaches and the method of Smith and Miller. Two new methods are described which have been developed during the last few years: the crack modelling method (CMM) and the critical distance method (CDM). These methods were tested by comparing their predictions with experimental data using a large database of 88 different notch geometries and materials. Notches were divided into three types: blunt, sharp and short. The CDM was found to be very successful for all types of notch, giving predictions within 20 per cent of experimental values in the great majority of cases. The CMM encountered difficulties with short notches; correction factors were developed to overcome this problem. Both methods can be used very easily in conjunction with finite element analysis, making them more useful than previous methods for the prediction of high-cycle fatigue in engineering components.


2014 ◽  
Vol 52 (4) ◽  
pp. 283-291 ◽  
Author(s):  
Gwan Yeong Kim ◽  
Kyu Sik Kim ◽  
Joong Cheol Park ◽  
Shae Kwang Kim ◽  
Young Ok Yoon ◽  
...  

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