Simulation with large deformation beam

I am doing a simple simulation of large deformation beam. I made a 2D Al/Ox bimorph and apply thermal expansion with delta T = 300K. I should expect the bimorph would curve into a perfect arc.Just like the first photo. With longer cantilever, it would curve into a circle. But the simlation tell me it will not. It looks like the bimorph will just goes up without curve back. I think the simulation is not correct. I already try to use "Segregated" in the solver but it doesn't work. But how can I change the setting of the solver?