Imagine. Is detail "Support". Under the terms of it work it has to withstand a load of 8000 N with the stresses of 110-120 MPa. At the same time, it should be the most lighter and cheaper. At same moment detail looks as shown in drawing.
It is necessary to optimize the design by changing the size of B1 and B2 so that it had has been the most lighter and satisfying the conditions of use.
You can also remove inefficient place of detail if they do not break its resistance to stress.
More information at this tutorial
Answered with a tutorial: https://grabcad.com/tutorials/tutorial-how-to-optimize-design-using-sw-simulation
Video Tutorial. For details on each action in a text tutorial