I am new to CAESAR, and new to this forum as well. New to stress calculations, so please excuse me if I am asking dumb things.
On the other hand I have 25+ years experience on modelling of pipe systems for dynamic analysis (pulsation and vibration problems). I also have been the project leader for the maintenance and development of the TNO 'PULSIM' software and the P3D graphical user interface for pipe systems.

I recently started using CAESAR for building/analyzing a pulsation damper with internals connected to a short piping section and try to calculate natural frequencies and vibration velocities.

I ran into the usual problems when starting with (for me) new software. I wrote down a few things that, IMHO, may help developers or others users to think about.

Would appreciate some feedback and am willing to help on further improvements. I do realize that CAESAR is special software and that one of the problems will be limited budget to make big changes. I can speak about that as a former project leader of similar software (PULSIM).

Here we go (btw, I use 5.0):

1 - General remarks

a - I still don't get used to the fact that there is a main window at program start up where you can load a piping model and nothing happens then! I have to start the piping input mode and get a second window which again allows me to load a model. But ONLY for the model type. I cannot load a structural model then. Very weird. Loading and saving a model should be kept at one place, with direct access to the model after loading.

b - CAESAR changes the extension of my piping model from 'C 2' to '_A' during a session and backward. Similar behaviour on structure files (str). Since the STR file is text format I got lost several times when I was editting the text input file for use in CAESAR...

c - If I link a structural file (STR) to a piping model and change the structural (STR) file, then the piping model does not reflect the updated structural file. Also deleting the link and creating a new link does not help! I have to load and save (!) the structural file to make it work.

d - I would love to see the possibility to set up a piping model with commands similar to the structural files. Text file editing without dealing with constant model checking or saying that things are not allowed is so much easier.

e - I did not manage to connect two piping parts at different coordinates to each other. I'll post this as a separate question on the forum.

2 - Remarks on the 'Classic Piping Input' window:

a - would prefer a much smaller input window size so that I have a bigger/better view on my model. Also would like to have window size and position saved. I keep on resizing and moving the window...

b - would be nice to have the navigation tools in the input window itself and not floating around

c - would like to have function keys or short cuts to step through the model while working in the CPI window. Reduced mouse movement.

d - please add units to the input fields, helps new user to understand what to enter

e - I often have trouble understanding the relation between the nodes and the parameters. I assume this has to do with the fact that CAESAR is based on elements rather than on nodes? I don't know what other people think of it, but I am used to think in nodes (with center points)

3 - Building a model for dynamic analysis

a - I found out that the solver does not convert pipes into smaller sections as needed for a dynamic analysis. So if you model one pipe with length 10 meter and anchor points at begin and end only, then you will get completely wrong results for the dynamic analysis. New users are not warned for this situation and may not be aware of it.

b - I would prefer to set up only boundary nodes or elements and divide the model into smaller pipe lengths at a later moment. That makes input so much easier. There is a function to quickly add extra nodes on a section, but when I make a mistake or decide to change the section length then the trouble starts: I cannot delete those intermediate nodes without changing the pipe routing. Deleting one or more nodes completely messes up the model since node position is relative (don't know who decided that, but it would have been much better to store absolute coordinates internally).

c - Then there's the problem with elbows. In my models they NEVER fit, because I have to use intermediate nodes (my chosen section length is about 1.5D). Maybe it helps if CAESAR already creates 2 extra nodes at the begin/end of an elbow (or starts generating nodes at that location).

4 - Postprocessor

a - The report function does not allow me to choose vibration velocities. But displacements and frequencies are already available. So it would have been easy to offer velocities in a report as well. For dynamic analysis it is custom to consider velocities and not displacements.

Looking forward to response!