Questions on solvers and optimization algorithms
I was wondering if someone could tell me a bit more about the reference stress, which can be found in the TOSS tab.
What units are used for it? Can I specify the yield strength of my material or a safety factor of it? How does this affect my result?
The TOSS method is a combination of the OC method and the SKO method. First, the finite element model is OC-optimized, followed by a SKO optimization step. During the first step, the FE model is optimized with respect to its stiffness, while the subsequent SKO optimization intends to homogenize the surface tension, so that in the end your model is optimal with respect to both stiffness and strength.
The reference stress, which can be set in the TOSS tab, belongs to the SKO method. It is a rough guide value for the desired surface tension of the optimized model. If you choose [N] and [mm] as units for force and length, the unit of the reference stress will be [MPa] = [N/mm^2].
Unfortunately, it is not possible to take into account the yield strength of your material or a safety factor during the optimization procedure. It is left to the user to check, if the stresses exceed the maximum permitted value. If so, the user has to adapt the optimization parameters manually.
I hope, this short explanation of the TOSS method is helpful to you.