XBP(1) 
YBP(1) 
XBP(2) 
YBP(2) 
XMU1 
XMU2 
CMU 

NoMirror 

12 
Card: Field 
Variable 

Description 
Original Units 
Default Units 
Metric Units 
12:1 12:2 12:3 12:4 
XBP(1) YBP(1) XBP(2) YBP(2) 
X’_{B1} Y’_{B1} X’_{B2} Y’_{B2} 
These coordinates define two points, 1=(X’_{B1,}Y’_{B1}) and 2= (X’_{B2,}Y’_{B2}), in the plane of the tire forces. These two points determine a boundary line, dividing the plane into two zones which may be assigned different coefficients of friction. This allows the user to simulate a vehicle running onto a dirt shoulder, a field, etc., or any similar situation which demands two adjacent areas of different frictional properties. The methodology for the friction zones was that the area on the origin side of the specified friction zone line was specified as friction zone No. 1. The area on the nonorigin side of the line was specified as friction zone No. 2. (Note: This creates a mirror image for friction lines which occur near the origin, i.e., friction zone 2 is repeated on the opposite (mirror image) side of the origin).(For Additional terrain friction specifications, see Friction Polygons option, To disable the mirror image characteristic, see NoMirror, field 9 below. 
inches
inches
inches
inches 
ft.
ft.
ft.
ft.

Meters
meters
meters
meters 
12:5 
XMU1 
μ 
The coefficient of friction in zone 1. It can be made to vary with speed (see 12:7); it is assumed independent of other factors within a zone. Suggested values are ~0.7 for dry pavement, ~0.5 for wet. See References 17 & 18 for approximate values for friction coefficients. 



12:6 
XMU2 
μ_{2} 
The coefficient of friction in zone 2. 



12:7 
CMU 
C_{μ} 
The coefficient of linear decrement of friction, varies μ with tire speed based on speed in in/sec. Please see discussion below. 
sec/in 

sec/cm 
12.8 
CMU2 
C_{μ2} 
The coefficient of linear decrement of friction for Vehicle2, If CMU2 is 0.0, then program will set CMU2=CMU. Please see discussion below. 
sec/in 

sec/cm 
12:9 
NoMirror 

Normally = 0.0 If set = 1.0, Option turns off the Mirror Image characteristic of the friction zone. The friction zone will only be effective in the quadrant(s) defined by the endpoints. 



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