Here's some general guidelines to follow for FEA simulations:

Sharp internal corners may cause inaccurate results

The finer the mesh of polygons, the greater the accuracy of your results

Minimum safety factor of 3 is recommended for designs. Shoot for 2x yield strength at least. The red zone signified the yield strength of the material has been reached and the part has failed.

Static stress studies are not ideal for materials with higher elasticity, such as rubber and plastic.

Static testing does not consider damping or inertial effects, such as momentum.

Stresses should not exceed yield-strength of material.

Load must cause deflections or rotations in the item under test.