Basquin equation

Considering smooth specimens, the ranges of applied stress or plastic strain control the fatigue or CF responses of metals for HCF and LCF conditions, respectively. For HCF, smooth specimen CF hfe increases with decreasing elastic stress range, at cycles in excess of the transition fatigue life, Nj-, according to the Basquin equation... 

In a double-logarithmic plot, the S-N curve of many metals is a straight line for a wide range of the number of cycles (see figure 10.18). This line can be described by the Basquin equation [14]... 

Large numbers of cycles (hcf) can only be reached with a small stress amplitude so that the amount of plastic deformation is small. The total strain thus corresponds mainly to the elastic part of the strain. The line can be described using the Basquin equation, re-written with the help of Hooke s law ... 

Fig. 10.22. S-N diagram of Si3N4 at different temperatures (measured in bending at ii = — 1) [113]. The dashed line is a fit according to the Basquin equation, common to temperatures of 20°C and 1000°C, whereas the dotted line is valid at 1200°C...

According to Basquin equation, the P-S-N curve satisfies the relationship ... 

Fig. 5.27 S-N diagrams for the steel used in the multileaf spring construction. The first is based on the S3, Sf determination. The second on the Basquin equation missing the plastic contribution to the strain...

The Basquin equation can be reformulated as Equation 4.9 to show the mathematical relationship between HCF and elastic strain ... 

The Basquin equation can also be remodified as Equation 4.10 to include the effect of mean stress. 

Equation Coffin-Manson equation Basquin equation... 

The correlation analysis of the corrosion fatigue behavior of Mg alloys at high stresses was carried out using so-called Basquin s equation [72] ... 

Once the analytical expression of the hysteresis loop has been derived, the following step is to infer the equation of the entire e-N curve or Wohler s curve. To this purpose, it is necessary to separate the two component of deformation, the elastic and the plastic one, as already done in Eq. (6.1). As to the elastic component Eg, it has been said in Sect. 5.2.2 that in 1910 Basquin [7] found a power law relationship with the cycles to failure N, see Eq. (5.22), so that in a log-log scale the elastic component of the S-N curve is a line. Later in the 50, Manson and Coffin [8-11] independently found that also the plastic component of the cyclic strain was related to life cycles N through a power law function, known as the Manson-Coffin relationship... 

Derive the S-N curve for the steel considered in sample problem 1. of Sect. 5.3 using Basquin and Manson-Coffin equations. To build the S-N curve the cyclic... 

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