HyperWorks Solvers

Pulley (/PROP/SPR_PUL)

Pulley (/PROP/SPR_PUL)

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Pulley (/PROP/SPR_PUL)

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Spring Type 12 – Pulley (/PROP/SPR_PUL)

Spring type 12 is used to model a pulley. When used in a seat belt model, it is defined with three nodes. Node 2 is located at the pulley, and a deformable rope is joining the three nodes (Fig. 3.7). The spring mass is distributed on the three nodes with ¼ at node 1 and node 3 and ½ at node 2.

A Coulomb friction can be applied at node 2, taking into account the angle between the two strands. Without friction, forces are computed as:

with, symbol_s being the total rope elongation and K being the stiffness. If the Coulomb friction is used, forces are corrected:

F = K (symbol_s1 + symbol_s2)

F2 = -F1 - F3

symbol_s1 is the elongation of strand 1-2 and symbol_s2 of strand 2-3.

springs_type12-pulley

Fig. 3.7: Spring type 12, pulley

Time step is computed with the same equation that for spring type 4; but the stiffness is replaced with twice the stiffness to ensure stability with high friction coefficients.

Note:The two strands have to be long enough to avoid node 1, or node 3 slides up to node 2. Nodes 1 and 3 will be stopped at node 2, if there is a knot at nodes 1 and 3.

springs_type12-locking

Fig. 3.8: Spring type 12, locking

For further information, refer to the RADIOSS Theory Manual.