Hello,
I am currently doing size optimization with Optistruct. I want to optimize material parameters (5 design variables), so that the frequencies of some desired modes match the frequencies obtained form experimental data. I have done a modalanalysis and checked which mode number my desired shapes have (e.g. shape 1 = mode_number 7; shape 5 = mode_number 32 and so on). As responses I defined the frequencies at the mentioned mode numbers. I activated mode tracking, because the mode numbers of my desired shapes are changing throughout the optimization process. I performed an optimization, but the converged solution wasnt ideal. So I tried the Global Search Option with the hope of finding other local minima. So far this worked as planned, I am getting some better designs.
But there is one problem: the GSO uses different starting point afaik. With that, the mode numbers may also change (e.g. shape 5 isnt mode_number 32 anymore, but mode_number 36). This completely ruins the idea of the optimization, because now different modes are optimized which even have the wrong desired frequency. This means that like half my starting points are wrong and it would take a lot of time to find out which are. Can I somehow tell Optistruct to always use the originally defined mode number (and change it through mode tracking if necessary) for each starting point? Or is there another work around?
