28.1.1. Contact Page
This page defines characteristic values to contact between two geometry entities. Sprocket, Single Flange, Double Flange, Center Flange, Flat Type, and Roller Guard. supported in RecurDyn are using this page.
Contact Normal Force
The contact normal force is obtained by
\(\mathbf{f}_\mathrm{n} = \mathbf{k}\delta^\mathrm{m1}+\mathbf{c}\frac{\dot{\delta}}{\left| \dot{\delta} \right|}\left| \dot{\delta} \right|^\mathrm{m2}\delta^\mathrm{m3}\)
where, \(\mathbf{k}\) and \(\mathbf{c}\) are the stiffness and damping coefficients which are determined by an experimental method, respectively. \(\delta\) and \(\dot{\delta}\) are a penetration and time differentiation of the penetration, respectively. The exponents \({m1}\) and \({m2}\) generates a non-linear contact force and the exponent \({m3}\) yields an indentation damping effect.
Characteristic: Defines the contact properties such as the stiffness coefficient, damping coefficient, and friction coefficients. Also, these coefficients can be given as user-defined spline curves.
Stiffness Coefficient: Specifies a stiffness coefficient for the contact normal force.
Stiffness Spline: The spline shows the contact normal force for the penetration. For more information, click here.
Damping Coefficient: Specifies a damping coefficient for the contact normal force.
Damping Spline: The spline shows the contact normal force for the velocity of penetration. For more information, click here.
Dynamic Friction Coefficient: Specifies a dynamic friction coefficient for the contact friction force. It has three options.
Dynamic Friction Coefficient: The constant friction coefficient is applied.
Friction Force Spline: The spline shows the fiction force for the relative velocity. It is recommended to use the spline that x and y values are defined as positive.
Friction Coefficient Spline: The spline shows the friction coefficient for the relative velocity.
More: Specifies some friction coefficients for the contact friction force.
Stiffness and Damping Exponent: Generates a non-linear contact normal force.
Indentation Exponent: Yields an indentation damping effect. When the penetration is very small, the contact force may be negative due to a negative damping force, which is not realistic. This situation can be overcome by using the indentation exponent greater than one.
Contact Output File: When this function is checked, RecurDyn creates the contact output file for contact information between sprocket and track links as follows. (Please refer to this option only output the results for track links, they checked at Output page in assembly information). The name of output file is ModelName_ContactName.out.
Col.
Variables
Descriptions
1
Time (sec)
Simulation Time
2
amount of contact point
Total number of calculated contact points
3
Pos_TX of Sprocket CM
Position X of Sprocket’s center marker
4
Pos_TY of Sprocket CM
Position Y of Sprocket’s center marker
5
Pos_TZ of Sprocket CM
Position Z of Sprocket’s center marker
6
Pos_PSI of Sprocket CM
Orientation Psi of Sprocket’s center marker
7
Pos_THETA of Sprocket CM
Orientation Theta of Sprocket’s center marker
8
Pos_PHI of Sprocket CM
Orientation Phi of Sprocket’s center marker
9
The index for contact points
10
Track Link ID
Contacted track link’s ID
11
Pos_TX of Track Link CM
Position X of Track Link’s center marker
12
Pos_TY of Track Link CM
Position Y of Track Link’s center marker
13
Pos_TZ of Track Link CM
Position Z of Track Link’s center marker
14
Pos_PSI of Track Link CM
Orientation Psi of Track Link’s center marker
15
Pos_THETA of Track Link CM
Orientation Theta of Track Link’s center marker
16
Pos_PHI of Track Link CM
Orientation Phi of Track Link’s center marker
17
The index for contact points
18
Global contact position
Global contact position
19
Contact position based on Sprocket
Contact position based on Sprocket
20
Contact position base on Track Link
Contact position base on Track Link
21
Normal force based on Sprocket
Normal force based on Sprocket
22
Friction force based on Sprocket
Friction force based on Sprocket
23
Normal force based on Track Link
Normal force based on Track Link
24
Friction force based on Track Link
Friction force based on Track Link
25
Velocity on Contact Reference Frame
Normal, Friction velocity based on contact reference frame
26
Velocity on Contact Reference Frame (Link Contact Point)
Velocity of Link Contact Point based on contact reference frame
(\(A_{c}^{T}\text{vel}_{j}\))
27
Angular Velocity on Contact Reference Frame (Link Contact Point)
Angular Velocity of Link Contact Point on Contact Reference Frame
(\(A_{c}^{T}w_{j\_ cm}\))
28
Velocity on Contact Reference Frame (Sprocket CM)
Velocity of Link Contact Point based on contact reference frame
(\(A_{c}^{T}\text{vel}_{i\_ cm}\))
29
Angular Velocity on Contact Reference Frame (Sprocket CM)
Angular Velocity of Link Contact Point on Contact Reference Frame
(\(A_{c}^{T}w_{i\_ cm}\))
30
Velocity on Contact Reference Frame (Link Pin)
Velocity of Link Pin on Contact Reference Frame
(\(A_{c}^{T}\text{vel}_{jpin\_ cm}\))
31
Angular Velocity on Contact Reference Frame (Link Pin)
Angular Velocity of Link Pin on Contact Reference Frame
(\(A_{c}^{T}w_{j\_ cm}\))
32
Velocity on Contact Reference Frame (Sprocket Contact Point)
Velocity of Sprocket Contact Point on Contact Reference Frame
(\(A_{c}^{T}\text{vel}_{i}\))
33
Angular Velocity on Contact Reference Frame (Sprocket Contact Point)
Angular Velocity of Sprocket Contact Point on Contact Reference Frame
(\(A_{c}^{T}w_{i\_ cm}\))
34
Velocity on Contact Reference Frame (Relative (Link Contact Point – Sprocket Contact Point))
Relative Velocity (Link Contact Point – Sprocket Contact Point) on Contact Reference Frame
(\(A_{c}^{T}\text{vel}_{j} - A_{c}^{T}\text{vel}_{i}\))
35
Velocity on Contact Reference Frame (Relative (Link Pin – Sprocket Contact Point))
Relative Velocity (Link Pin CM – Sprocket Contact Point) on Contact Reference Frame
(\(A_{c}^{T}\text{vel}_{jpin\_ cm} - A_{c}^{T}\text{vel}_{i}\))
28.1.1.1. Friction
Dynamic Friction Coefficient: Specifies a dynamic friction coefficient for the contact friction force.
More: Specifies some friction coefficients for the contact friction force.
Static Threshold Velocity: If the relative velocity between a contact pair is less than this value, the friction coefficient is defined as following.
\(\mu =\text{step5}(\nu ,\,\,-{{\nu }_{s}},\,\,{{\mu }_{s}},\,\,{{\nu }_{s}},\,\,-{{\mu }_{s}}\,)\)
Dynamic Threshold Velocity: If the relative velocity between a contact pair is greater than this value, the friction coefficient is same as the specified dynamic friction coefficient. If the relative velocity between a contact pair is greater than “Static Threshold Velocity” and less than this value, the friction coefficient is defined as following.
\(\mu =\text{step5}\,(\nu ,\,\,{{\nu }_{s}},\,\,-{{\mu }_{s}},\,\,{{\nu }_{d}},\,\,-{{\mu }_{d}}\,)\)
Static Friction Coefficient: Specifies a static friction coefficient.
The friction force of contact elements is determined by the following equations.
\({{f}_{f}}=-\,\text{sign}\,(v)\,\,\left| \mu (v) \right|\,\,\left| {{f}_{n}} \right|\)
where, \({{f}_{n}}\), \(\mu (v)\), and \({{f}_{\max }}\) are the contact normal force, the friction coefficient, and the maximum friction force, respectively. The friction coefficient of \({{f}_{f}}\) is determined by a relative and tangential velocity on the contact point as shown in Figure 28.6.