Open Access
Table 1
Notations and definitions of parameters. Subscripts R, N and S refer to roller, nut and screw respectively. Subscripts SR and NR refer to roller‐screw and roller‐nut contacts. The subscript i refer to the position along the mechanism axis, see Figure 3b.
| PRSM design parameters | Hertz contact | ||
|---|---|---|---|
| P | Pitch of the mechanism | ρi,j | Main curvature of surface i, direction j |
| rN, rS, rR | Nut, screw, roller radii | β | Angle between main curvature frames |
| rext | External radius | α | Non‐linear Hertz constant |
| n | Contacts per roller (max: 25) | E, K | Elliptic integrals of first kind |
| nR | Number of rollers (max: 8) | ||
| Ni, Si, Ri | Nut, screw, roller ith position | ||
| Loads and stiffness | Mechanical Parameters | ||
| F | External load | E | Young Modulus |
| fSR,i, FNR,i | Load at ith contact | v | Poisson ratio |
 |
Average load per contact | Lt | Fatigue limit in pure torsion |
| kN, kS, kR | Nut, screw, roller bulk stiffness | Lf | Fatigue limit in pure bending |
| kSR, kNR | Equivalent contact spring constant | τDV | Dang‐Van criterion |
| Linear algebra | Experimental parameters | ||
| K | Stiffness matrix | Nrep | Number of repetitions |
| X | Position vector | Fmax | Maximal force |
| P | Pitch effect | dmax | Maximal displacement |
| F | Non‐linear and external loads | ||
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