I am trying to find a function fit to my data plotted. And these are the $x-y$ data:
$x$: 0.0020 0.0050 0.0100 0.0200 0.0500 0.1000 0.2000 0.5000 1.0000
$y$: 4.4417 4.5548 4.8820 5.4256 21.5676 46.8372 50.1357 67.5797 623.3367
It will be much appreciated if you may tip me what kind of function behavior can be close. My guess was $tanh$ which has the slope of zero at $x=0$ but I was not quite successful.
$y$ are the critical load to rupture an elastomer vulcanize by solid particle and the $x$ are normalized sizes of particles.