Does your computer have 20 cores or 10 cores with 2 threads on each core? The Task Manager will show twice as many CPU usage bars as there are physical cores if hyperthreading is enabled. I disabled hyperthreading on my 16 core machine. ANSYS will only use one thread per core and if you look in the solve.out file, it will tell you how many physical cores it can detect.
ANSYS solver licenses come with the ability to run on 2 cores.
If you want to solve on more cores, you need to have an HPC license (except the Student license has HPC built-in). These licenses are expensive! To find out if you have an HPC license start the following program:
In the text window, look for anshpc:
Users of anshpc: (Total of 16 licenses issued; Total of 6 licenses in use)
You can see that we have 16 available and someone is using 6 right now, which means he is running a job with 8 cores, since you get 2 cores from the solver license. If I had a 20 core machine, I could only run on 18 cores with this license. Since I have a 16 core machine, I can use 14 HPC licenses to run on 16 cores, leaving 2 HPC licenses. Someone else could run a 4 core job with the remaining HPC licenses on a second solver license.
I have found that my structural problems don't scale well. That means when I go from 2 to 4 cores, the solve time is reduced by a factor of 1.8 but when I go from 4 cores to 8 cores, the reduction factor is only 1.4 and going from 8 to 16 cores the reduction is only 1.1 so I generally don't take the last 10% and instead run on 8 cores and often start a second job on 8 cores. This gets me a reduction factor of 2 for the 2 jobs that run simultaneously.
HOW TO USE MORE CORES
In Mechanical, Solve Process Settings, click Advanced and type in how many cores you want to use.
If you also use My Computer, Background, you have to select that and click Advanced to set cores for a background solve.
EXPLICIT DYNAMICS vs TRANSIENT DYNAMICS
Have you tried to solve using Transient Dynamics?
Why do you need to use Explicit Dynamics?