Hi Casaba (@potyka_csaba),

You could use the following equations to create the desired load profiles.

Load1: **F1*((t-1)*(t>1)-2*(t-2)*(t>2))*(t<3)** //where F1 is the magnitude of load 1

Load2: **F2*(t-3)*(t>3)** //where F2 is the magnitude of load 2

The resulting load profiles are shown in the image below.

However, I’m not sure what the purpose of time step 3 is, as this is the same load case at time step 1. If time step 3 is not required you can save computation time by using the following equations.

Load1: **F1*((t-1)*(t>1)-2*(t*(t-2)*(t>2))**

Load2: **F2*(t-2)*(t>2)**

Correction

As @potyka_csaba points out below Load1 should have been:

Load1: **F1*((t-1)*(t>1)-2*(t-2)*(t>2))**

This eliminates the time step between the two load peaks as shown in the image below.

You can plot the difference between two load cases using the **Python Calculator** in ParaView. In the **expression** field you can use an equation like this:

**inputs[1].PointData[“von_Mises_stress_(signed)”]-inputs[0].PointData[“von_Mises_stress_(signed)”]**

where:

input[0] = bolt pretension only

input[1] = load1 + bolt pretension

This will result in a plot that contains the effect of load1 only.

However, this is only valid if the direction of stress is substantially the same in both cases. This is because stress is a vector quantity and the difference should be calculated vectorially.

In theory this should be pretty straight forward. It is just a case of subtracting one Cauchy stress tensor from the other. The resulting Cauchy stress tensor can then be used to calculate the “von Mises stress difference”. This is not something that I’ve done but it is something that I’m interested in doing. If I get the time I may have a go at this over the next few days otherwise @rszoeke might be able to help out here.