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DR is an explicit time integration method [6], which is applied in our scheme to simulate the above-mentioned system. With the information of the state of the previous time step and the forces currently exerted on the system, we can calculate the state of the subsequent time step.

Translational motion is described by nodal positions and translational velocities, while rotational motion is described by nodal orientations and angular velocities. The rates of change of translational velocities and rotational velocities are proportional to the residuals of translational forces and torques exerted on nodes. The update formulations for translation motion and rotational motion are listed in Tab. 1. The derivation and the application of these formulations are illustrated in our previous work.

Table 1: Translation and rotation formulations of DR
Translational part	Rotational part

With proper damping, the kinetic energy is reduced to zero and a static state can be derived. We use two different damping methods: For the translational degrees of freedom we use kinetic damping, setting every translational velocity to zero once the translational kinetic energy of the system begins to decrease. For the rotational degrees of freedom we use velocity damping, multiplying every angular velocity by a factor less than one at each time step [7].