## Card 98 - Secondary Collision Model - Veh1 Trailer or Veh3

The interaction of a trailer attached to vehicle#1 (or a separate Veh#3) and vehicle#2 has been added to the m-smac program.  The exterior dimensions for the collision interface are taken from the trailer (specified on input Card 22, fields 7-9) or Veh#3 (as specified on cards 50-60) and using the exterior dimensions of vehicle#2 (Input card 5, fields 7-9). This card (Card 98) is analogous to input card 13, wherein the inputs for the Collision Model are specified for the interaction between the Trailer of Vehicl#1 (or Veh#3) and Vehicle #2. Users are cautioned that due to the potential differences with the crush properties of the part of the trailer (under ride of the trailer, impact on the tandem axles, etc.) and normal car-to-car type impacts, the use and/or choice of inputs for interaction between the trailer and vehicle are not well defined.

 DELPS02 DELRHO2 ALAMB2 ZETAV2 AKV2(1) AKV2(2) AMU2 98

 Card:  Field Variable Description Original Units Metric Units 98:1 DELPS02 ∆ψ2 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 98:2 DELRHO2 ∆ρ2 The increment of change of the radius vector. (See explanation after card 13.) A value of around  0.1 is recommended. inches Cm 98:3 ALAMB2 λ2 The acceptable error in inter-vehicle pressure equilibrium. Choose λ greater than Kv21 times ∆ρ and also greater than Kv22 times  ∆ρ   (see explanation after card 13). e.g. for Kv21 = 30.0,  Kv22 = 50., and  ∆ρ2= 0.2, then λ could be 12. lb./inch N/cm 98:4 ZETAV2 ζv2 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 ZETAV2 A value of around 5.-20. Is recommended. in/sec cm/s 98:5 AKV2(1) Kv21 Load-deflection characteristic of V1 Trailer (see explanation after card 13). Values range from around 40 to around 500. lb/inch2 N/cm2 98:6 AKV2(2) Kv22 Same as above, but for V2 for interaction with V1 Trailer. 98:7 AMU2 μv2 Inter-vehicle friction coefficient: This is the coefficient of friction between the  two vehicles when they are in contact and the adjacent surfaces of V1Trailer and V2 are moving with respect to each other (at a velocity greater than ζV2). 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).

More:

Card 99 - Veh#3/Trailer Release Option