Integration of areas obtained from Force-displacement curves

Hi,

I have force-displacement curves I would like to interpret by calculating different areas. The raw data comes in a excel file, with 2500 data points. Some of the areas I would like to obtain include straight lines, and due to the combination of data points and functions (lines) it is hard to integrate the different areas. I've tried, as you can see in attached script. The problem is that the area of elastic work sometimes becomes negative since the total work I've calculated doesn't take the negative values into account.

Do anyone have suggestions how to solve this problem? Or to calculate the different areas? I also attach a figure describing what I want to obtain.

Thanks in advance!!

[Nalini Vishnoi]

Can you please elaborate on what is the question here? Looking at your code, you are able to successfully compute the area under different curves and the value of 'elasticarea' is also positive (at least for the given example). It would be helpful if you can provide an example where the elastic area is negative (when it should not be).