## Card 13 - Collision Model, Crush Properties

 DELRHO ALAMB ZETAV AKV(1) AKV(2) AMU FMOVIE 13

 Card:  Field Variable Description Original Units Metric Units 13:1 DELPS0 ∆ψ The interval between radial vectors. The SMAC program calculates all collision forces in a clockwise sweep about the center of gravity of V1. The sweep  is broken into increments  (360/ DELPSO must be an integer).  Too large a value of  DELPSO will cause inaccuracies;  too small a value will exceed the  program's capacity. The collision interface is  handled in a  table of up to 200 points. If more than 200 points are required to handle the damage area, the message "ISTOP=9" appears on the  printout.  The suggested value is 1 degree, which can be increased (e.g. to 2 or 3)  if the error message "ISTOP=9" appears. degrees 13:2 DELRHO ∆ρ The increment of change of the radius vector. (See explanation after card 13.)  A value of around  0.1 is recommended. inches cm 13:3 ALAMB λ The acceptable error in inter-vehicle pressure equilibrium. Choose λ greater than Kv1 times ∆ρ and also greater than Kv2 times  ∆ρ   (see explanation after card 13). e.g. for Kv1 = 30.0,  Kv2 = 50., and  ∆ρ= 0.2, then λ could be 12. lb./inch N/cm 13:4 ZETAV ζv The minimum relative velocity for full inter-vehicle  friction. If, while in contact, the adjacent surfaces of the two vehicles move with respect to each other  at a speed less than this, the effective inter-vehicle friction increases, starting from zero, as a linear function of the relative velocity and it reaches the full value at ZETAV A value of around 5.-20. Is recommended. Note for higher values of AMU (field 7) use of lower zetaV values may produce rapid fluctuations in the direction of the resultant accelerations (chatter). in/sec cm/s 13:5 AKV(1) Kv1 Load-deflection characteristic of V1 (see explanation after card 13). Values range from around 40 to around 90. lb/inch2 N/cm2 13:6 AKV(2) Kv2 Same as above, but for V2. 13:7 AMU μv Inter-vehicle friction coefficient: This is the coefficient of friction between the  two vehicles when they are in contact and the adjacent surfaces of V1 and V2 are moving with respect to each other (at a velocity greater than ζV). The force  tangent to the interface opposing the relative motion = μv times the force with which the surfaces are pressed together.   A value of about 0.55 is recommended (The maximum range of this input should be from 0.0 to 1.0). 13:8 FMOVIE If >=0, write time history of damage display (for graphics program). To omit , set < 0.

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