| A method is presented to include collision detection and dynamic impact analysis into an already existing mechanism simulation program. The Integrated Mechanisms Program (IMP) is capable of kinematic and dynamic analysis. However, the capability to detect collision between parts of the mechanism, and for dynamic impact analysis have not been available heretofore.;The collision detection method in this research relies on a fast algorithm for determining the minimum distance between parts which are represented by polykedral solids. This algorithm is valid only for convex polyhedra; therefore a partitioning of general non-convex solids is necessary for collision detection. The performance of the collision detection algorithm is enhanced by the use of certain other techniques such as the collision detection of bounding spheres.;After a collision is detected, sometimes it is necessary to continue the simulation. This requires the dynamic impact analysis of the collision. To be able to perform this, the time of first contact as well as the type of contact, point of contact, and plane of contact are determined.;Dynamic equations for impact are developed by using the Lagrangian approach similar to the development of the dynamic equations of motion in IMP. The dynamic impact model used may be simple or complex depending on the inclusion of multiple types of impulses which may occur during the impact. The simplest model is concerned only with the normal impulse, while the more complex model may include tangential impulse, moment impulse, and torsional impulse. With these impulses as additional unknowns, additional equations are obtained from coefficients used to define the impact model. Examples of such coefficients are coefficients of restitution in the normal and tangential directions. The dynamic impact equations, which are linear equations, can be set up and solved when these coefficients are provided.;A program is written to implement these ideas. Selected examples demonstrate that the program performs correctly with only a small penalty in computing time for the simulation. With this implementation, it is now possible to simulate a mechanism whose parts may collide, and also a reasonable prediction can be made of what will happen following the collision. |
