Dynamic analysis of many mechanical systems is often involved with contacts among
bodies. This paper presents an efficient and general-purpose contact search algorithm for multibody
dynamics in the context of the compliance contact force model. While many conventional collision
detection algorithms are based on the absolute coordinate system, this paper proposes to use the
relative coordinate system in detecting a contact. A boundary box of a defense surface geometry is
divided into many blocks. A contact reference frame is defined on the defense body of a contact
pair. Since all geometric variables necessary to detect a contact are measured relative to the contact
reference frame attached to the defense body, the variables belonging to the defense body are
constant, which significantly reduces computation time associated with the contact search.
Therefore, the contact reference frame plays a key role in developing an efficient contact search
algorithm. Contour of the defense body is approximated by many piecewise triangular patches,
while contour of the hitting body is represented by hitting nodes along its boundary. Bounding
boxes inside which contain each body of a contact pair are defined at a preprocessing stage to
eliminate an exhaustive contact inspection when two bodies are in a distance. If two bounding
boxes are turned out to be in a contact during the pre-search, each node on the hitting boundary is
inspected to find out to which block the node belongs in the post-search. Since each block dividing
the boundary of the defense body has a list of patches, each node on the hitting boundary is tested
for a contact only with the patches in the block that the node belongs. Actual contact calculation is
then carried out to find the contact penetration used in calculating the compliant contact force.
Numerical example is performed to demonstrate the validity of the proposed method.
T-4-4-3 An Efficient Contact Search Algorithm using the Relative Coordinate System for Multibody System Dynamics
