Hi, i have data from my experiments and i want to plot the strain-time curve with it and then identify the most linear part (it will be the steady state part in the middle) of it so that i can calculate the slope of this part to get the steady state creep rate. I am attaching the data(1), fitting equation(ε=θ1(1−exp(−θ2t))+θ3(exp(θ4t)−1)):(t=time,e=strain) and an example of how the curve looks like. I tried polynomial fit and then drawing a slope at the inflection point but it doe not give me a consistent result.
Also, the data2 is from such an experiment which was interrupted due to unknown reason and the data shows jump in strain during the last duration of experiment, so is there a way to extrapolate the data upto 0.01 strain?(i have to later iuse these two data and find an average plot which i can interpolate later).
Please help me, i have been stuck at this for quite some time and i have to use these plots for my thesis submission scheduled next month.
Appreciate your input and thanks in advance.