  This paper provides a method for the simultaneous topology optimization of
parts and their corresponding joint locations in an assembly. Therein, the
joint locations are not discrete and predefined, but continuously movable. The
underlying coupling equations allow for connecting dissimilar meshes and avoid
the need for remeshing when joint locations change. The presented method models
the force transfer at a joint location not only by using single spring elements
but accounts for the size and type of the joints. When considering riveted or
bolted joints, the local part geometry at the joint location consists of holes
that are surrounded by material. For spot welds, the joint locations are filled
with material and may be smaller than for bolts. The presented method
incorporates these material and clearance zones into the simultaneously running
topology optimization of the parts. Furthermore, failure of joints may be taken
into account at the optimization stage, yielding assemblies connected in a
fail-safe manner.
