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Fit a Curve by Estimating UTS

An empirical formula can be used to estimate SN/EN data from ultimate tensile strength (UTS) and Young's modulus (E).

  1. From the Assign Material dialog, click the My Material tab and select your created material.
  2. Select Estimate from UTS as the input method.
  3. Click to view the model description.
  4. Enter a value for UTS and Elastic modulus.
  5. Click Estimate.

SN Properties



Figure 1. SN Method Description
SRI1
Fatigue strength coefficient. It is the stress amplitude intercept of the SN curve at 1 cycle on a log-log scale.
b1
The first fatigue strength exponent. The slope of the first segment of the SN curve in log-log scale.
Nc1
In one-segment SN curves, this is the cycle limit of endurance (See Nc1 in Figure 2). In two-segment SN curves, this is the transition point (see Nc1 in Figure 4).
b2
The second fatigue strength exponent.


Figure 2. One-segment SN curve in log-log scale (b2=0) (Nc1 is not defined or less conservative than FL)


Figure 3. One-segment SN curve in log-log scale (b2=0) (FL is not defined or less conservative than Nc1)


Figure 4. Two-segment SN curve in log-log scale

EN Properties



Figure 5. EN Method Description
Sf/σ′f
Fatigue strength coefficient.
b
Fatigue strength exponent.
c
Fatigue ductility exponent.
Ef/ε′f
Fatigue ductility coefficient.
Np/n′
Cyclic strain-hardening exponent.
Kp/K′
Cyclic strength coefficient.
Nc
Reversal limit of endurance. One cycle contains two reversals.
SEe
Standard Error of Log(N) from elastic strain.
SEp
Standard Error of Log(N) from plastic strain.


Figure 6. EN curve in log-log scale