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 non-origin 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

μ₂

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.