As the body of a car is crushed, it exerts a force
that is approximately proportional to that crush. The SMAC program assumes that
at any point on the interface between the two vehicles, the pressures exerted by
the two surfaces must be equal and opposite. Units for pressure are in
pounds/inch^{2} (2-dimensional). The pressure is assumed to be
proportional to the depth of crush. In finding equilibrium of crush forces, the
depth of crush on each vehicle is adjusted by ∆ρ until the pressures on the two
vehicles are within an allowable error of λ. For solution stability it is
necessary that **λ> K _{v}**

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