Hello all,

i just made stress analysis of a rectangular plate of 100x100x5 mm. With its bottom fixed and a force of say 10000N on top face. Actually stress=F/A which should be 10000/10000=1N/mm^2. But i am getting 1.8N/mm^2. What exactly is problem but i am sure simulation cant go wrong in a simple problem like this. Is my approach of the problem correct, kindly correct me if i am wrong. Thanks

Shankar H.S,

Below are two stress plots for a 1ooo mm square flat plate and a load of 100,000 N. The first was run with a fixed lower face. Vertical translation was fixed. The resulting stress is 100,000 N/m2 which is what you expect.

The second was run with the lower face havng translation fixed in all three degrees of freedom. This means that elements adjacent to the lower face will not, as Bill notes, be able to move laterally due to the Poisson effect. The additional restraints introduced in this case induce high local stresses particularly on the lower outer edges.

The restraints or boundary conditions assumed in the manual calculation you mentioned correlate to the first plot.