Figure 1.
Setup of an FPMD simulation for assessing molecular friction between seven bundles of the amorphous phase and two crystalline units.
(A) Schematic representation of the model before equilibration (left). The two crystalline units (red) are 3 nm apart, and seven bundles of the amorphous phase (blue) are placed around it. The loading and boundary conditions of the model are indicated (right). A harmonic spring that moves with constant velocity V was connected to the termini of the seven bundles. The crystalline units were position-restrained in pulling and in one lateral direction. (B) The MD simulation system (left) with a front and top view of mid-sections (middle), and an enlarged view of interactions between the crystalline and amorphous component (right).
Figure 2.
Friction force per residue () as a function of pulling velocity (
) when pulling the amorphous phase along the crystalline units.
Both amorphous-crystalline and amorphous-water friction contribute to the total friction.
Figure 3.
Simulated coefficient of viscosity per residue as a function of shear stress .
Red and black lines present fits of the stochastic model to the simulation data with varying ma and , respectively. The solid red line shows the best fit to the data.
Figure 4.
Finite element modeling of interfacial friction.
Schematic picture of the finite element model with boundary conditions (left). The model includes the crystalline unit (blue), the amorphous phase (yellow), and contact surfaces (right). The master segment was assigned to the crystalline unit surface (magenta), and the slave segment to the amorphous phase surface (brown).
Figure 5.
Stresses in the crystalline and amorphous components as well as the interface segments as a function of their relative velocity.
(A) The crystalline cube was pulled horizontally along the amorphous rectangular plate of 0.5 nm thickness. (B) The crystalline cube was pulled with a 10 degree angle with respect to horizontal plane along the amorphous component of 2.85 nm thickness.