Why is the Keep Non-Design Spaces Function resulting in a straight connection?

The optimisation goal of MSC Apex Generative Design is a stress value. This results in an optimised shape which is evenly loaded and has uniformly distributed stresses.

In some cases Non-Design Spaces without a load or a comparable low load are supposed to be part of the optimised shape. However, if these Non-Design Spaces are located in areas where the stress is lower than the Stress Goal material is reduced. The material can be reduced so much that the Non-Design Spaces are no longer connected to the rest of the structure and are lost.

With the Keep Non-Design Spaces Function activated the algorithm will always reconnect these Non-Design Spaces to the remaining structure. If there is only a low stress level in this area, the connection will be only a strut as shown in the picture below.

In this case an already existing force should be increased or an additionally Force and Event should be added with disturbing forces to create some stress in this area. Thus, good and stable connections can be realised. If the strut-connected Non-Design Space is a Fixation, the fixation is maybe unnecessary and can be reduced. How this is possible is described here.