Hello, this is my first time posting here.
We are currently considering the design with reference to the spring technical data. Regarding the allowable stress of thin flat springs, if we try to design a flat spring with both amplitudes where the same load is applied vertically, σmax=-σmin. In such a case, can the value of γ be 1? 
The fatigue limit for both amplitudes should be evaluated as 60% of the one-amplitude fatigue limit for flat springs. You can estimate the fatigue life by adding ×0.6 to the fatigue limit diagram described on our website and plotting the points of the single-amplitude vibration condition (stress 0 when the spring is at its free height to maximum stress σmax) on the diagram.
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I would like to confirm the contents of the above reply.
> Taking into account the fatigue limit diagram on our company’s website, ×0.6 is added to the N number in the bending stress-fatigue strength diagram, (10^7×0.6 if N=10^7), is it correct?
>Under the single-amplitude vibration condition (stress 0 when the spring is at its free height to maximum stress σmax), the lower limit stress coefficient is 0, and the upper limit stress coefficient is the maximum stress value on that amplitude. Is it correct?
Create a fatigue limit diagram in which ×0.6 is added to the fatigue limit diagram described on our website, and plot the points of the single-amplitude vibration condition (stress 0 when the spring is at its free height to maximum stress σmax) on the created diagram to estimate the fatigue life.
The upper limit stress coefficient is the maximum stress σmax divided by the minimum value of the standard value of material tensile strength. The lower limit stress coefficient is the minimum stress σmin in the numerator. Thank you!
