Estimate Basquin constants from SN curve 
Select to let the program calculate the Basquin equation constants based on the given data points of the SN curve. For high cycle fatigue (number of cycles N > 10^{4}) an SN curve can be approximated by a straight line when plotted on a loglog scale. Basquin’s equation is a power law relationship between the applied stress cycles (S) in the yaxis and the number of cycles to failure (N) in the xaxis.
Basquin’s equation is only valid up to the endurance limit or fatigue limit. The endurance limit is the highest alternating stress that does not result in fatigue failure. In other words, if the alternating stress is equal to or lower than the endurance limit, the number of stress cycles to cause failure becomes very large (practically infinite). The endurance limit is usually defined for zeromean alternating stresses. The endurance limit is also called the fatigue limit. Some metals do not have a measurable endurance limit.
The program considers the stress range values Sr for the Basquin equation. It multiplies by 2 the alternating stress values (Sa) of the SN curve to account for a fullyreversed load (Sr = 2*Sa).
The Basquin’s equation of the SN fatigue curve is given as:  N = B / (Sr) ^{m} , or
 log (Sr) = B  m log (N)
When you select this option the Curve specific constant (B) and Slope of SN curve (m) options are inactive. The software calculates the B and m constants by fitting a straight line through the SN data points using the leastsquares line fitting technique. These constants are material parameters determined by fatigue testing experiments under different stress levels.

Units 
Sets the units for the stress range Sr. 
Consider the cutoff point for the SN curve at row 
Sets the cutoff point of the SN curve that is considered for the calculation of the Basquin constants. If you enter 0 or 1, all the data points of the SN curve are considered for fitting a straight line using the leastsquare fitting method. For example, if you enter 4, the data set of the first four rows of the SN curve are considered for fitting a straight line and calculating the Basquin constants B and m. It is recommended to use as a cutoff point the fatigue endurance limit. The SN curve is considered a horizontal line after the cutoff point.

Curve specific constant (B) 
Enter the value ( must be positive real number) for the SN specific constant B. This is the value of the stress range Sr at one cycle. 
Slope of SN curve (m) 
Enter the value (must be a positive integer) for the slope of the SN curve m. When two data points (N_{1}, S_{1}) and (N_{2}, S_{2}) are known, the slope of the SN curve m is given by:

Source 
Enter information about the source of the SN data. 
View 
Select to view a graph of the SN curve. 
Save 
Saves the SN curve data in a *.dat or *.csv (comma delimited) file format. 