How to use TSRES command in Ansys APDL

[MtzMechEngr]

Hello,
I have a transient heat transfer analysis question where I heat a plate for a short duration and then evaluate thermal response.
The duration of heat pulse occurs for .1 seconds at time t = 1 second and thermal response time I would like to evaluate is 1 minute.
I use an Ansys APDL table to create heat pulse as shown below:
t = 0; HF = 0;
t = .99; HF = 0;
t = 1.0; HF = 10000;
t = 1.1; HF = 10000;
t = 1.11; HF = 10000;
t = 60; HF = 0;

I also create a TSRES_ARRY which is an ANSYS APDL array that lists exact time values where I want Ansys APDL solver to use during transient time run.
t = .99;
t = 1.0;
t = 1.1;
t = 1.11;

I then apply heat flux to face of plate and issue following command which forces transient solve to include times listed in TSRES_ARRY.
TSRES,%TSRES_ARRY%

However, when I run the solver, I receive following error:
Increments between time points set by array TSRES_ARRY for TSRES must be larger than the initial time step set by DELTIM or NSUBST

I find that this error may be resolved by decreasing time step and max time step to 0.1 seconds. However, this makes the solver take a really long time as the time at end of load step is 1 minute and I am using .1 second increments to reach this time!

How can I force Ansys APDL to have a fine time step in beginning of transient analysis (first two seconds) and then use a more course time step for rest of analysis (from 2 to 60 seconds)?

 

[Achy47]

Hello,

Thank you for your question. It seems like you are trying to control the time step size for your transient analysis in a specific way. One approach you can try is to use the command TSCALE to set a time scaling factor for your analysis. This will allow you to specify different time scales for different parts of your analysis.

For example, you could set a time scale of 0.01 for the first 2 seconds and then switch to a time scale of 0.1 for the rest of the analysis. This way, the solver will use a finer time step for the first 2 seconds and then switch to a coarser time step for the remaining 58 seconds.

You can also try using the command DT, which allows you to specify a time step size for a specific load step. This way, you can set a smaller time step for the first load step and then increase it for the subsequent ones.

I hope this helps and please let me know if you have any further questions. Best of luck with your analysis!