Premise:
In explicit simulations the values entered in the Displacements and Rotation boundary conditions generally are applied through an “amplitude”, so that the values are not applied instantly, but gradually during the step. Let’s assume the amplitude is a simple straight line: 0,0; 1,1.
Question:
If the amplitude is defined with “Step time”, the boundary condition should reach the input value at the end of the step time, while if the amplitude is defined with “Total time”, the boundary condition should reach the input value after 1 second (unitary time). Am I right? At least this is how I remember from my 10 years with ABAQUS explicit (9 years ago).
In PPM the amplitude is always used as “Total time”, as far as I tested.
Have in mind that step time can be defined by the user and is not necessarily equal to 1. However, step time always starts at 0 at the beginning of each step. The total time is equal to 0 only at the start of the analysis, and then it is incremented using the step time.
In PrePoMax you can select the Step time or Total time when creating an amplitude.
Keep in mind that in explicit dynamics, it makes a huge difference for calculation time if you use e.g. 1 s or 0.1 s for step time (due to the stable time increment concept). It’s quite common to artifically speed up the simulated phenomena but you can also use mass scaling. Just control the kinetic energy.
Also, explicit dynamics in CalculiX is usually not a good choice because it’s still highly underdeveloped, slow and has several limitations.
I remembered incorrectly about the step time. I am in the Ansys world now, hahaha
I used to develop ABAQUS explicit rolling models (casade of rolls) with adaptive mass scaling; we had viscous (plasitc) material properties and we could not speed up. I could say that I have some experience with explicit simulations;).
I was courious about the present capabilities of PrePoMax and Calculix in simulating hot metal rolling. I guess it is possible, but is slow and the interface would need development.
