We have axial stress and strain data that we recorded for each cycle during the fatigue tests. We are trying to find out the Young's modulus of the loading and unloading part of each hysteresis curve. Visco-elastic effect of the materials provides us very short linear section which makes us difficult to calculate the slope of the loading and unloading section. We are using 95% linearity (as per ASTM standard) of the loading and unloading section, but we are getting a huge scatter in the data. I am wondering to know if there is any other criteria we can follow to calculate the Young's modulus. A sample data set and the schematic representation of the method we are using are attached.
Dear Dulal Saha,
very interesting data sets. To me it seems as if your material has gone through a most significant Change of properties comparing the Change of Hysteresis after 10 cycles with that after 250 000 cycles. Did you carry out any structure damage Analysis to make sure the specimens are still in proper conditions. What Kind of cyclic Speeds (frequencies) did you apply? Is the material a carbon fiber epoxy Composite?
Best regards, R. Rentsch
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