m-smac includes a provision for the specification of up to two polygon friction zones. Polygon friction zones provide the user with the option to specify irregularly shaped friction zones.
The original SMAC program included the provision for two friction zones defined by the user specification of a line (Card 12). The area defined by the line that included the origin is considered friction zone 1, and the area on the other side of the line from the origin is considered friction zone 2. A mirror image is inherently included in this type of specification.
In addition to the original provision for specification of friction zones, m-edit has added the flexibility of polygon friction zone specification. The user defines one or two polygon(s) (Card 30) of up to 48 points (Card 31) each with their own friction coefficient specification. The program checks at each time increment whether a tire in on or in the polygon area. If the tire is on or in the polygon then the friction coefficient of the polygon zone is used for the individual tire. This option permits the simulation of curved friction areas like those adjacent to roadway curves which are not easily defined by a single straight line. Also, provisions for ice patches and other friction areas can easily be included in the m-smac run.
The inputs to m-edit for the Polygon Friction Zone are on Cards 30,31 and 32: