Hello!
I have posted about this project a few times and gotten excellent help. I am designing a study to evaluate the effectiveness of simulations to model the behavior of loose-tube fiber optic cables. The running theory (I say theory but this is pretty well known) is that a higher excess fiber length (EFL) leads to higher attenuation after temperature cycling - essentially as the temperature drops, the cable jacket shrinks but the glass does not - so fibers push against one another and agains the jacket and this stress leads to worse performance. With a higher excess fiber length (EFL) you are essentially just shoving longer fibers into the same amount of space. So you would expect the stress to be higher with more material cramped inside the cable pushing against everything. We have shown in real samples that higher EFL generally leads to worse attenuation. ]
In SOLIDWORKS, I have modeled this EFL as a tube extruded along an equation driven line. The "waviness" represents the extra length that gets pulled into the cable. I use different amplitudes on the equation to model more or less EFL. Again, the theory was that higher amplitude - so morematerial inside the cylindrical jacket, would lead to higher stress and contact pressure on the fibers/between the fibers - and lower amplitudes would give the fibers more room to move around, resulting in less contact pressure.
To ensure the models were as comparable as possible, I have a mesh control on the outermost surface where I would be looking at contact pressure. I also copied and pasted the simulation between each trial, changing ONLY the amplitude of the equation driven line to simulate change in EFL.
After 3 simulations, I exported contact pressure data to excel - i selected the surfaces of the fibers (all 12) and saved them to a spreadsheet. To my shock, the tests with higher EFL/greater amplitude resulted in lower contact pressure - lower average, lower maximum, lower number of contact points. This makes very little sense to me and I was wondering if someone here could make heads or tails of that, or if there's something I did wrong to analyze/export the data.
I did notice that the different simulations had different numbers of datapoints/nodes which makes them a little hard to compare, but I would still expect the maximum value for contact pressure to be higher on the simulations with higher EFL/Amplitude. I can even see on the contact pressure plot that the lower EFL models seem to show bigger hotspots. Maybe I need to rethink how I am modeling the excess length.
If anyone has any suggestions at all I will be eternally grateful!
High EFL/Amplitude ^^
Low EFL/Amplitude ^^
