The block is designed to simulate the contact friction of two translatory moving surfaces with a variable pressing force.
The relative slip speed v in m/s is determined by the formula:
where vC and vR – linear speeds at ports "C" and "R", respectively, m/s.
Defining the friction curve is possible in two ways: the Stribeck curve and the tabulated curve.
Stribek curve
When using this method, the Stribeck friction curve [1] and viscous friction (Figure 1) are used to determine the friction force.
Figure 1. Dependence of friction force on relative speed
The friction force is determined by the formula:
where:
FC and FC – forces applied to ports "C" and "R", respectively, N
Fbrk – breakaway friction force, N
Fc – dry (coulomb) friction force, N
vth – breakaway speed, m/s
C – damp ratio, s/m
Fr – factor of internal friction, N·s/m
Friction forces Fbrk and Fc are calculated depending on the value of the pressing force according to the formulas:
where:
N – pressing force, N
μ – breakaway friction factor
μs – dry (coulomb) friction factor
Tabulated curve
Using this method the friction factor is defined by interpolating a given table. If the slip speed exceeds the value specified in the table, extrapolation is not carried out.
The friction force is determined by the formula:
where μ(|v|) – friction factor value obtained as a result of interpolation.
Inputs
Name
Description
Connection line type
C
Port for connecting a conditionally fixed case (case)
Translatory mechanics
R
Port for connecting a conditionally movable rod (rod)
Translatory mechanics
N
Specified pressing force
Mathematical
Outputs
None.
Properties
Title
Parameter
Description
By default
Data type
Friction curve
A group of properties that define the friction parameters
Friction model
MType
Friction model type The possible values are: "Stribek curve", "Tabulated curve”
