I have a bar 100mm long and 10X10 cross section, held at one end.

I apply an axial load to the other end. The load and temperature remain constant over 100 seconds.

I get the following displacement "curve" for a node at the end of the bar over the 100 seconds.

Material is defined as follows:

Obviously a deflection of -0.3mm at T=0 is nonsense but the bilinear nature of the curve is puzzling me as well.

Any ideas?