Prepare Data

Each file in the list can be edited individually.

Requirements:

  • Normalize the x axis to 1 (1 represents 100% strain).

  • Define Young’s modulus manually or automatically.

    To normalize the abscissa (x-axis) in a raw data file, select the file, set a scale value for the xvalues, and then hit Scale to multiply the axis values by that factor. For example, if the X values of the raw data are in percent [%], set the X value to 0.01 and then press Scale.

    The raw data curves can be shifted horizontally along the x-axis if the starting point is not close to the origin (x-axis zero). Click the Shift key to move the curve to the defined value.

    Negative values are also allowed, and in this case the shift is in the opposite (horizontal) direction.



    Figure 1. Normalization and horizontal movement of the data curves

    There are two ways to define Young’s modulus:

  1. With YM Eval, the Modeler automatically starts fitting the elastic part and a new graph appears showing the Young’s modulus. The adapted value is displayed in the field below the Young’s Modulus (modulus of elasticity).
  2. Move the slider to manually adjust the Young’s modulus, after the initial identification. This is required for all imported files/curves.
  3. Deactivate the Automatic check box and enter a value manually to set the Young’s modulus to a specific value. Use the slider to further adjust the value.
  4. Select All Curves to set this value for all imported files/curves.


    Figure 2. Automatic or manual definition of Young’s Modulus
    Smooth noisy or oscillating data using the Smooth button. For repetitive curves, you can use the Add Mean button to derive a mean curve and select the curves for averaging.
    Check or uncheck the box to subtract the elastic part of the 0.2% strain if you want to consider the Rp0.2 value (useful for metals), which is often provided by material manufacturers. Some materials are characterized by early softening with a very long plasticizing strain.
    Note: It is necessary to define the necking point manually as it is useful for plastics and high-strength steel.
  5. Select Necking Point and define this point for each selected curve.


    Figure 3. Manual selection of the Necking Point
  6. To complete the preprocessing of the data, click Workup. The curves are recalculated to True-Stress vs. True-Plastic-Strain. The elastic portion of the strain hardening curve is subtracted. The curve is cut and the end of the elastic area up to the necking point is left for further processing.