RESEARCH ON THE MOVEMENT LAW OF “BALLS ON AN ELASTIC BAND”

A topic of 2022 IYPT “Balls on an Elastic Band” is studied. Under the condition of linear assumption of torsion force and damping of rubber band, a two-degree of freedom linear damping free torsional vibration model is established to describe the motion law of elastic band with double ball. A shear deformation mechanical model of elastic circular axis is established to describe the mechanical properties of elastic band, and the analytical solution is given. The pendulum behavior of the double ball rubber band system is explained, and the dependence between the behavior and the related parameters is explored quantitatively. The Tracker software was used to obtain relevant experimental data to verify the correctness of the model. The constant period breaking phenomenon in the experiment was explained semi-quantitatively, and the change of the nonlinear revolution radius r with time t was analyzed qualitatively.